Magnetic Encoder Actuator Series For decades, our talented team of engineers has been defining and developing advancements in actuator technology. The Magnetic Encoder Series, for instance, boasts industrial-strength gears with heavy-duty, long-life motors and PWM, TTL standard or optional RS-485 protocol capabilities. Available in a wide range of sizes with highresolution, 32-bit programmable digital circuits, Hitec Commercial Solutions actuators meet the most rigorous demands for a plethora of commercial applications. Inquire about our customization and modification options, tailor-made for your specific projects. • Magnetic Encoder Position Sensors • Wide Voltage Operation • High-Resolution Programmability
• Sizes Ranging From 13mm ~ 33mm • Precise Repeatability • Customization Options Available
Servo Actuator Engineering Reimagined Hitec Commercial Solutions, Inc. | 12115 Paine St., Poway, CA 92064 | (858) 748-6948 | www.hitecnology.com
Full Page.indd 2
12/4/2017 8:26:19 PM
SERVO MAGAZINE ... Paving the way for the next generation of Robotics Experimenters!
GAZINE SERVO MAGAZINE SERVO M SERVO MAGAZINE SERVO MAGAZIN ERVO MAGAZINE SERVO MAGAZINE GAZINE SERVO MAGAZINE SERVO M SERVO MAGAZINE SERVO MAGAZIN ERVO MAGAZINE SERVO MAGAZINE GAZINE SERVO MAGAZINE SERVO M SERVO MAGAZINE SERVO MAGAZIN ERVO MAGAZINE SERVO MAGAZINE GAZINE SERVO MAGAZINE SERVO M SERVO MAGAZINE SERVO MAGAZIN SV Sub Ad.indd 3
12/4/2017 9:09:22 PM
02.2018
SV TOC - Feb 18_TOC SV Mar 15.qxd 1/3/2018 5:14 PM Page 4
VOL. 16 NO. 02
Subscription Information SERVO Magazine — PO Box 15277 North Hollywood, CA 91615-9218 Call 877-525-2539 or go to www.servomagazine.com Subscribe • Gift • Renewal • Change of Info For more details on subscribing, see our ad on Page 3.
PAGE 40
PAGE 07
The Combat Zone 16 18 21 25 26 29
SPARC GETTING STARTED GUIDE Before You Build Your First Bot Component Selection Weapon Systems Custom Fabrication Packing for an Event What to Expect at an Event
Departments
06 Mind/Iron
Microcontrollers — They’ve Finally Made it to Cracker Jacks
13 Events Calendar
13 64 65 66
Showcase RoboLinks Advertiser’s Index SERVO Webstore
14 Bots in Brief • • • •
There’s Something Fishy about You Does this register? Can you see me now? Flame on, HUBO!
SERVO Magazine (ISSN 1546-0592/CDN Pub Agree#40702530) is published monthly for $26.95 per year by T & L Publications, Inc., 430 Princeland Court, Corona, CA 92879. PERIODICALS POSTAGE PAID AT CORONA, CA AND AT ADDITIONAL ENTRY MAILING OFFICES. POSTMASTER: Send address changes to SERVO Magazine, P.O. Box 15277, North Hollywood, CA 91615 or Station A, P.O. Box 54, Windsor ON N9A 6J5; cpcreturns@servomagazine.com
4
SERVO 02.2018
SV TOC - Feb 18_TOC SV Mar 15.qxd 1/3/2018 4:09 PM Page 5
In This Issue ...
07 Evaluating Your
Drone Needs
The Multi-Rotor Hobbyist by John Leeman It’s often difficult to decide what to buy nowadays.There are so many multi-rotor products for every conceivable need that it’s hard to know if we should buy a certain model of aircraft, build our own from scratch, or if we should own a few different models for different purposes. To help with this, we’re going to give you the ultimate guide to buying, building, and accessorizing your drone.
31 The Making of Andros
by Mitch Anderson I wanted to put my skills to work for something useful. I decided to design a police/military robot. I knew that they are very expensive, and I thought I could do a prototype that would be more affordable. Here’s how it went.
36 Avoiding Obstacles while Following a Line with the Scribbler 3
40 The STEAM Maker Festival
Contributed by student writers This particular event is a collaborative venue for students, educators, and professionals within the San Diego, CA community and industry to demonstrate programs, projects, practices, and resources that enrich STEAM education. Read reports from five students who give their impressions of the Festival.
CNC Routers
by Roger Secura If you’ve been mulling over the idea of building a CNC router, I should warn you the learning curve is quite steep. This article will help you flatten out part of that learning curve by covering the basic hardware and software requirements for building a CNC router.
53 Ultrasonic Radar Refresher
by Dan Harres Robots commonly performing obstacle detection rely on active sensing. This tutorial will go over some fundamentals of locating stuff with ultrasonic radar.
by John Blankenship Many people know that Parallax’s Scribbler 3 robot can draw pictures with precise movements because of its wheel encoders. However, the Scribbler’s IR and line sensors along with access to a hacker port provide capabilities that make it a contender for more mainstream robotic projects.
46 Beginner’s Guide to
PAGE 58
58 Robots in Our Lives
Then & Now: Advances in robotics from the past up through today. by Tom Carroll For those of us who don’t yet own a robot for our house, it certainly is at the top of our wish list; either as one that we build from scratch or buy from a retailer. So, are the home robots on today's market truly what we've always envisioned as a personal companion robot, or are we still playing catch-up to Rosie the Robot?
PAGE 31
SERVO 02.2018
5
Bergeron - Mind-Iron - Feb 18_Mind-Iron - Feb15.qxd 1/3/2018 1:09 PM Page 6
Mind / Iron by Bryan Bergeron, Editor ª
Microcontrollers — They’ve Finally Made it to Cracker Jacks ids of all ages know that Cracker Jacks have a prize inside. Maybe a decoder ring. Maybe a toy soldier. Maybe a rub-on tattoo. Whatever the prize, it’s by default a low-cost commodity item. If something has made it to the status of a Cracker Jack prize, it’s probably nearing extinction in the free market. Of course, microcontroller boards aren’t really available in Cracker Jack boxes — at least, not yet. However, they’re cheap enough now where I consider them not worth repurposing — that is, they’re disposable. Take the popular Arduino, Raspberry Pi (strictly speaking, a microprocessor board) and, say, the Wi-Fi enabled NodeMCU. They’re all available for $5-$10 in single-unit volumes. At those prices, it’s not worth spending an hour unsoldering and disconnecting prototype circuits. Aside from the issues of whether to repurpose commodity microcontroller boards, the affordability of these boards means that there is no excuse for the robotics experimenter to become fluent in their operation. One challenge is picking a processor board and going with it without constantly looking back. For example, lately, I’ve been spending a lot of time interfacing Arduinos to the ESP8266 to webenabled devices. The NodeMCU incorporates the ESP8266 and essentially provides web access for free. Even more attractive is the NodeMCU’s support for the interpreted programming language Lua which — for beginners — is simpler to learn and use than the flavor of C supported by the Arduino. The great upside to virtually free embedded hardware is a future where everything has embedded
K
6
SERVO 02.2018
intelligence. Forget bar codes being replaced by dumb RFID chips. Bar codes on everything from fruit to lawnmowers will be replaced with intelligent chips that tell the user the history of the item from inception to stacking on the store shelves. Imagine if the chip embedded in the carton of eggs could warn you that the temperature rose to 70 degrees for an hour during transport. Or, that the cut of beef originated from a cow that was given a double injection of growth hormone. Or, that the box containing your potentially new LCD TV was subjected to a 9G drop during delivery. That’s all data you’d probably be willing to pay a few cents for, right? The only downside to ubiquitous embedded processing power is probably loss of privacy. Sure, your washing machine might be able to query your pants to determine if they’re sweaty and grimy enough to need a good washing. But do you want your employer to check out your clothes as you walk into the office? Maybe you like to wear your shirts two or three times before laundering them — but not if everyone else in the office wears a freshly washed shirt every day. I’ve been trying to devise a way for my running shoes to indicate when the cushion has bottomed out — but I don’t want to be inundated with Google ads for running shoes. At pennies per processor, what data would you want automatically posted to the web by embedded processors? Would you let Amazon or some other online store monitor your refrigerator, your clothes, and your daily activity? In short, do you see the potential for good outweighing the potential for harm? SV
FOR THE ROBOT INNOVATOR
ERVO
Published Monthly By T & L Publications, Inc. 430 Princeland Ct., Corona, CA 92879-1300 (951) 371-8497 FAX (951) 371-3052 Webstore Only 1-800-783-4624 www.servomagazine.com Subscriptions Toll Free 1-877-525-2539 Outside US 1-818-487-4545 P.O. Box 15277, N. Hollywood, CA 91615 PUBLISHER Larry Lemieux publisher@servomagazine.com ASSOCIATE PUBLISHER/ ADVERTISING SALES Robin Lemieux robin@servomagazine.com EDITOR Bryan Bergeron techedit-servo@yahoo.com CONTRIBUTING EDITORS Tom Carroll Kevin Berry R. Steven Rainwater John Leeman John Blankenship Roger Secura Dan Harres Mitch Anderson Mike Jeffries Eric Davis Lucie Kaskoun Annika Huff Luke Rohen Sam Benedict CIRCULATION DEPARTMENT subscribe@servomagazine.com WEBSTORE MARKETING COVER GRAPHICS Brian Kirkpatrick sales@servomagazine.com WEBSTORE MANAGER/ PRODUCTION Sean Lemieux sean@servomagazine.com ADMINISTRATIVE STAFF Re Gandara Copyright 2018 by T & L Publications, Inc. All Rights Reserved
All advertising is subject to publisher’s approval. We are not responsible for mistakes, misprints, or typographical errors. SERVO Magazine assumes no responsibility for the availability or condition of advertised items or for the honesty of the advertiser. The publisher makes no claims for the legality of any item advertised in SERVO. This is the sole responsibility of the advertiser. Advertisers and their agencies agree to indemnify and protect the publisher from any and all claims, action, or expense arising from advertising placed in SERVO. Please send all editorial correspondence, UPS, overnight mail, and artwork to: 430 Princeland Court, Corona, CA 92879.
Leeman - Multi-Rotor Hobbyist - Feb 18_Blank Rough SV.qxd 1/3/2018 2:58 PM Page 7
Evaluating Your Drone Needs By John Leeman
It’s often difficult to decide what to buy nowadays. There are so many products for every conceivable need that are just a second day air shipment away from being pressed into service. In the multi-rotor space, it’s hard to know if we should buy a certain model of aircraft, build our own from scratch, or if we should own a few different models for different purposes. After the purchase or build, it’s hard to know what you’ll need to keep your drone happy and healthy. This month, we’re going to give you the ultimate guide to buying, building, and accessorizing your drone.
Evaluate Your Needs The first step in buying a drone starts with a frank conversation with yourself. Before you go and look at any of the displays or read online reviews for hours, you need to know exactly what you’re looking for. What aspect of this hobby interests you? What kind of piloting skills do you have or want to develop? What’s a realistic budget? There are four basic types of drones in my mind: 1) 2) 3) 4)
Photo/video Beginner/toy Experimental Racing/acrobatic
For someone wanting to get into the hobby to get beautiful and stunning video from high above, the Figure 1: The Cheerson CX-10 is a blast to fly around and is an photo/video category is what you’ll be looking for. These inexpensive way to have a lot of fun, but it is far from a are often larger airframes to produce more stable video and serious hobbyist’s interests. accommodate larger motors/propellers for a higher lifting going to advanced systems later easy and a treat. capacity as you upgrade to bulkier cameras. While the CX-10 is really meant only for indoor flying, a The control loops for these drones are often tuned for good starting point for the outdoors might be the Syma high stability and slower response times for smoother X5SW-V3 (Figure 3; http://amzn.to/2kRmRSF) or similar. movements that won’t jar viewer’s stomachs. You’ll also These pack a lot of punch for under $50, with a Wi-Fi often notice that these airframes stand higher off the camera and basic stability control. I started my multi-rotor ground to allow room for the camera/gimbal assembly to hobby with one of these models and got many hours of hang below. fun from it. The beginner/toy category encompasses the lowest cost and most basic drones on the market. These range from the $19 Cheerson CX-10 (Figure 1; http://amzn.to/2kgEJlM) which we’ve hacked before in this column, to the few hundred dollar semi-intelligent models like the Parrot BeeBop (Figure 2; http://amzn.to/2nObVpV). The lowest end toy drones have little in the way of automatic stability, no GPS, and often no camera. They use a proprietary remote and are really an advanced toy to play with. Not for the serious hobbyist, but fun for some backyard time and for Figure 2: The Parrot BeeBop (and newer model 2) are on the high end of those brand new to flying. the toy spectrum as they have live camera streams, basic Learning how to fly on a no-frills drone makes programmability, and GPS functionality. (Image courtesy of amazon.com.) SERVO 02.2018
7
Leeman - Multi-Rotor Hobbyist - Feb 18_Blank Rough SV.qxd 1/3/2018 2:58 PM Page 8
To post comments on this article and find any associated files and/or downloads, go to www.servomagazine.com/index.php/magazine/issue/2018/02.
Figure 3: For those looking to dip their toes into flying a quad, the Syma X5SW-V3 is a great starting place and economical at under $50. (Image courtesy of amazon.com.)
Many readers of SERVO will likely be drawn to the experimental category. These are multi-rotors that come as kits or plans. Often, you’ll need to assemble, program, or otherwise tinker to get these off the ground. While they are
more work to get flying and keep them there, you do learn a lot about the fundamentals. It’s also generally much easier to try different motors, flight controllers, or other gear. Instead of everything being kept in a nice injection molded housing, there are frame members that you can drill into and more easily mount your own gear. Great power can be accompanied by great headache or epic crashes following a bad solder joint. If you want a fully customizable experience and have the time, this is a fun route. The final category is the thrill-seeking bunch. Acrobatic and racing drones are generally small in size and phenomenally over-powered compared to any other category. These drones will shoot straight up at an alarming rate, scream by at traditional car-like speeds, and send video back to their pilots wearing FPV (First Person View) goggles (Figure 4). While there are some ready-to-fly (RTF) models out there, many racers tend to straddle the experimental category, upgrading their airframes to carbon-fiber, adding faster motors, more aggressive propellers, or better cameras. Personally, I’ve never been that interested in drone racing, but it has become a popular sport with TV placement on major networks and competitions around the country. If you’re looking for a competitive real life video game-like experience, these hot rods might be for you.
Build or Buy? One of the next questions you’ll have to grapple with is whether to build or buy your multi-rotor. The answer is a complicated optimization of time, money, technical skills, tooling, and desire. First off, is there a commercially available product that will do what you want? If there is, it’s doubtful that you’ll be able to do it from scratch for a similar price and with as
Figure 4: FPV flying is common amongst the racing sport, but can be fun for the general hobby flyer as well.
8
SERVO 02.2018
Figure 5: The DJI Phantoms are an incredibly feature-rich line of products at an intermediate budget that will keep you busy for many weekends of exploration. (Image courtesy of amazon.com.)
Leeman - Multi-Rotor Hobbyist - Feb 18_Blank Rough SV.qxd 1/3/2018 2:58 PM Page 9
The Multi-Rotor Hobbyist elegant an interface. For example, do you want or need to be able to stay in the air? If you’re racing, if you want a versatile quad with it’s probably not as long as good video capability but aren’t someone wanting to fly a grid trying to make a major motion collecting images for picture, and you don’t plan on photogrammetric reconstruction. hacking extra functionality onto A good time to aim for is 15-20 the flight controller, the DJI minutes. There are the normal Phantom line (Figure 5) is hard to tradeoffs of weight/lift and beat with models ranging from battery size to consider if you are $500-$800. building your own. If you don’t want to be Automated flight modes and locked into the camera and the features of the flight controllers on commercial drones, controller are next on the list. If you’ll be giving up those nice you’re purely wanting something control apps for the iPad, and to fly as a model aircraft hobby, there likely won’t be a customer then you’ll probably be fine with a support line. You are customer Figure 6: Phone and tablet integration is a nice feature, basic flight controller where you support! but one that can go out of date if the manufacturer have full control of the vehicle at On the other hand, if you stops supporting the particular hardware you have. It does open up the opportunity for third-party services all times. want an exceptionally large quad such as Drone Deploy and others. (Image courtesy of If your goal is data collection or want one to do a specific task, dronedeploy.com.) or if you’re a new pilot that is building may be the right choice. more interested in video or other aspects of the hobby, It could also be the right choice if you’re looking to learn you’ll probably want a controller that does the flying for some new skills, need an excuse to invest in more tools, or you with the pilot simply inputting need a project to keep you busy through the winter. up/down/forward/backward/yaw commands. If you’re not Building lets you research each component, learn the sure where you are on that spectrum, it’s worthwhile to try details, and choose what suits your needs best. flying in a simulator and if you can, get hands-on with a A good place to start is the past articles of this column fully automated drone. where we cover the basics of motors, speed controllers, I’ve always had completely manual quads, which wasn’t propellers, and other essential parts. Building is a lot of fun a problem coming from a model airplane background. The and certainly the most versatile option, but isn’t for first time I got my hands on a Phantom, it was magical. everyone or for the hobbyist who wants a Suddenly, I could enjoy the scenery I was flying over, try to flying/photography/racing hobby but not a frame shots, and other fun tasks instead of focusing on mechanical/electronics one. staying in the air. Again, it’s a matter of what you’re On the market, you’ll find multi-rotors that are ready to looking to get out of the hobby. fly out of the box at many levels, as well as some kits that Return home is a highly-recommended feature, but one are almost ready to fly (ARF). There are also some drones only found on at least semi-intelligent vehicles. If you lose that are bind-n-fly (BNF) where you provide the RC your quad, can’t figure out the orientation, or if the battery transmitter, pair it with the receiver in the quad, then fly gets low, the drone will automatically return to the takeoff away. For hobbyists with their own gear that just want to location and land. There have been a number of times I add another aircraft to their collection, this is an attractive would have really loved to have this feature on different option. quads I’ve owned. A related feature is integration with your tablet or phone (Figure 6). I don’t know of any after-market flight controllers with app integration. While it’s a bit of a risk Now that you know what kind of multi-rotor you’re in that the app will get outdated in several years, the the market for, it’s time to make a list of features you want. likelihood of a drone that is frequently used for years If you’re planning on buying a commercial product, you’ll surviving unscathed is low. (Remember, never take off with want to compare this list to the features listed for each more money that you are ready to lose!) drone you are considering. If you’re building, it provides a Many of the homebuilt solutions will have different good set of constraints that you can use to help calculate equipment for receiving and viewing live video, controlling the required battery size, motors, propellers, etc. We’ll the quad, etc. Commercial solutions tend to revolve around cover a few of the common features that you’re likely to be mobile devices as places to show video, telemetry, and considering. provide context aware control buttons. The fancy solution is The first thing to think about is flight time. How long
Features to Consider
SERVO 02.2018
9
Leeman - Multi-Rotor Hobbyist - Feb 18_Blank Rough SV.qxd 1/3/2018 1:11 PM Page 10
Figure 7: Smart chargers are a great way to keep your batteries healthy and happy, and are generally safer and more reliable that the less expensive chargers. (Image courtesy of amazon.com.)
nice, but you are limited to the functionality implemented by the manufacturer. Homebuilt solutions often revolve around open source projects that you can modify to suit your needs. The final common consideration is the camera. Do you want or need a camera? Are you just going to use the camera to fly the drone in a first-person way, or do you want to record 4K video to show off where you went on that weekend hike? Commercial solutions with integrated cameras are very nice as the camera and flight controller can coordinate to give you incredibly stable video that is “vehicle aware” so you aren’t showing your landing gear in 4K. These can be harder or impossible to upgrade, though, as newer technology becomes less expensive. Adding your own camera is a bit more work and may involve some more hardware/software for the control, but it can be exchanged for another bit of gear or upgraded much more easily. If you’re serious about aerial photography, it’s likely that you’ll want to experiment with different gear for different scenarios and to keep up with the latest and greatest.
Accessories Like many other major purchases, the budget should include a non-trivial amount for accessories. While a basic airframe and radio will get you in the air, you’ll be stranded after the first crash or waiting on batteries to charge after each flight. I’ll cover a few things that I’d consider necessities when buying a new vehicle. Extra batteries are a must. For your 15 minutes of flying fun, you’re likely to be faced with a multi-hour recharging process for the batteries. Having a couple of extra batteries is highly recommended as it’ll make pulling
10
SERVO 02.2018
Figure 8: Battery safes are a must as they keep you and your property at a much lower risk should a battery fail catastrophically. (Image courtesy of amazon.com.)
out the drone and going flying a lot more fun and rewarding. With enough batteries, you could probably keep rotating them all afternoon, but I find that after a couple hours of flying, my brain needs a recharge as well and it’s time for a cup of coffee. I also tend to buy pretty high capacity batteries to maximize the flight time on each one — especially since I like doing longer data collection type flights. To go with your batteries, you’ll want a decent charger. Exactly which charger you’ll want depends on how many batteries of what size you want to charge and how fast. There are inexpensive chargers for around $20 (or included with your kit) that will charge a single battery slowly, often taking four hours or more. They also are not that smart generally. Getting a smart charger (Figure 7) that can help run maintenance cycles to keep your batteries healthy, report on bad cells, and more is worth the investment. It’ll reduce your frustration when finding a bad battery on the flight line, and keep you from running or charging batteries with dangerous failures. The final battery related item is a good battery safe (Figure 8). These fire-resistant bags help reduce the risk of a major catastrophe if your battery fails when being charged or stored. If your battery is not in use, it should be stored in a fire bag. We’ve all seen the videos of lithium-ion batteries failing in great clouds of smoke and molten metals. It’s a quick way to lose a lot of property. These are inexpensive and will help you sleep at night as you envision shorted battery cells starting a bon fire in your basement. Getting a field bag to put your drone, transmitter, batteries, etc., in is also a nice accessory. I’ve hauled multiple quads across the country without a protective bag and it was not pleasant!
Leeman - Multi-Rotor Hobbyist - Feb 18_Blank Rough SV.qxd 1/3/2018 1:11 PM Page 11
The Multi-Rotor Hobbyist
Figure 10: For the serious traveler, Pelican cases are the ultimate in gear protection. I’ve floated down a river on one of these before while the equipment inside stayed safe and dry. (Image courtesy of pelican.com.)
of the year is out of the question, have a look at these simulators. RealFlight 8 even has VR capabilities. Figure 9: Semi hard-sided backpacks are a great way to keep your quad safe on the way to and from the field and in the back of the car. (Image courtesy of amazon.com.)
Crash Kit
While you’re preparing your order, it’s a good idea to Having a hard-sided or semi hard-sided case is well go ahead and build up a crash kit. There’s a saying that worth the investment. There are backpack and roller styles there are two kinds of pilots: those that have crashed and out there offering various degrees of crush protection. For those that will. Everyone will crash at some point due to the casual hobbyist, the semi-hard sided backpack (Figure the wind, operator error, sun glint, or a variety of other 9) is a great place to start. The more serious may want to invest in a Pelican case (Figure 10) that can survive commercial shipping and airline baggage handling (but remember the restrictions on batteries in the cargo hold of an aircraft when travelling with your drone!). x Design New Ideas The final accessory I’ll recommend isn’t really a drone accessory, but one for the pilot. Look into the various x Prototype Without model flight simulators out there. the Wait RealFlight is the most popular and the one I have, though my copy is x Cut Real Metal pushing a decade old now. These give you a real transmitter to use while flying a virtual airplane, helicopter, or x 120VAC - Plug in CNC Mill drone model. Starting at: Anywhere The best part is that the crashes cost nothing and all the repairs happen instantly with the push of a button. If you’ve never flown before TORMACH.COM or live in a climate where flying part
smallmachine BIGRESULTS
$4950
SERVO 02.2018
11
Leeman - Multi-Rotor Hobbyist - Feb 18_Blank Rough SV.qxd 1/3/2018 1:11 PM Page 12
reasons we come up with. Building a crash kit doesn’t have to be prohibitively expensive and can prevent your Saturday morning flying session from being cut tragically short due to a minor incident. Extra propellers are a must. When taking off and landing, it’s all too easy to accidently dig one side of the drone into the ground and bend or break the propellers. Replacements are generally not that expensive, and it can be fun to have a few different sizes and pitches in your bag for more stable or more acrobatic flights. Balance these at home before heading to the field. To do some basic maintenance on your drone in the field, carry a simple tool kit. Pliers, combination wrenches, maybe some sockets, and a file should be a good start. Having the basics with you makes it easy to quickly recover from a broken part without a trip back to the shop. Zip ties and string are the basics of all good field kits (and duct tape too). I use these to strap on instruments to the airframe, patch together a broken landing gear leg, or tie that pesky wire out of the way before it gets cut in half. Pick up the big can of various sized zip ties next time you go into the hardware store. It’s also a good idea to have any easily replaceable parts on hand. This could be a motor mount, extra prop
nuts, extra screw, Loctite, etc. Generally, these items are not that expensive, plus you will need them eventually (remember how we started this section).
Where to Buy Now that you know what you want, what accessories you’ll need, and have made sure you’re within your set budget, it’s time to place an order ... but from where? There are many online marketplaces as well as brick-andmortar stores that now carry multi-rotor products. The biggest consideration here is how much support you want or need. I’ve often found that nothing beats going into your local hobby store with parts in hand and asking for help. The workers generally can help you put the pieces together and suggest products as they themselves are hobbyists. If you get help there, it’s only right to buy there as well and support the store. (It’s also a great way to support local businesses!) Sometimes the prices are a bit higher than big-box stores or online, but try to get the sales person at one of those to talk about which battery they like best on their aircraft. Amazon is also an obvious contender here. With Prime members getting free second day air shipping and a huge variety of products and parts to choose from, it’s certainly an option. If you don’t need support or are looking for the largest number of reviews, this is a good place to go. Hobby King is the other big player in the model aircraft space. Their prices on imported goods are often outstanding, but sometimes the quality control can be lacking. The shipping fees are also quite high, so planning one large order is best here.
Closing Thoughts So, in the end, it’s really a matter of tradeoffs. What’s the value of your time to build and program a fully customizable drone when all you want to do is take beautiful aerial video? How much time will you spend working with the constraints of a commercially available drone to get it to do exactly what you want? Hopefully, this guide has led you down some useful paths and you feel confident in making your leap into the world of multi-rotors. I’d also like to thank you for reading this column since it began in May 2016. Sadly, this will be the last installment. I’ve thoroughly enjoyed learning about this emerging area of technology and sharing it with you, but the time has come to move on to other projects. Keep innovating and experimenting, and as always, fly safely. SV
12
SERVO 02.2018
Rainwater - Events - Feb 18_Events - Aug 15.qxd 1/3/2018 4:09 PM Page 13
EVENTS FEBRUARY 2-7
AAAI Mobile Robot Competition New Orleans, LA See website for this year’s event information. www.aaai.org/Conferences/conferences.php
21-25 Apogee University of Illinois at Urbana-Champaign, IL Events include I-Strike, Robots at War, Track-o-Mania, and Student Design Competition. www.bits-apogee.org
MARCH 1-4
Pragyan National Institute of Technology, Trichy, India See website for this year’s event information. www.pragyan.org
9-10
Greater Philadelphia SeaPerch Challenge Temple University, Philadelphia, PA Tethered underwater ROV missions. www.phillynavalstem.com
9-10
Midwestern Robotics Design Competition University of Illinois at Urbana-Champaign, IL See website for this year’s event information. http://mrdc.ec.illinois.edu
15-18 Techkriti RoboGames Indian Institute of Technology, Kanpur, Uttar Pradesh, India Events include IARC, AIRC, Robowars, and Manoeuvre. www.techkriti.org 17-18 First LEGO League of Central Europe Finals Aachen, Germany Event this year is Hydro-Dynamics. https://www.first-legoleague.org/en/fll/tournaments.html 24
Manitoba Robot Games TecVoc High School, Winnipeg, Manitoba, Canada Events include Mini Sumo, Prairie Sumo, Tractor Pull, Line Following, Robo Critter, Super Scramble, and LEGO NXT/Mindstorms. www.scmb.mb.ca
Did You Know ...
Preferred Subscribers get access to all digital back issues of
SERVO Magazine for free? Call for details
1-877525-2539 or go to
www.servo magazine.com SERVO 02.2018
13
bots
Bots in Brief - Feb 18_Bots in Brief Mar15.qxd 1/3/2018 1:15 PM Page 14
IN BRIEF
THERE’S SOMETHING FISHY ABOUT YOU Robots may be getting more realistic, but most of us can still discern a human from a humanoid. Fish, on the other hand, seem easier to fool. Researchers at École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have developed an aquatic robot that can infiltrate schools of zebrafish, going so far as to influence their activities. By designing robots to integrate with animal communities, the roboticists hope to unravel these animals’ behavioral and social structures by learning more about how they communicate. “We wanted to study how a robotic agent can be inserted in a fish shoal, and, when inserted, how this robotic agent could learn how the fish interact, communicate, and take decisions,” Frank Bonnet, an EPFL postdoctoral researcher who worked on the project, told Digital Trends. “We created a kind of ‘secret agent’ that can infiltrate these schools of small fish,” Bonnet stated with a smile. Bonnet is a post-doc researcher at the LSRO (The Laboratoire de Systèmes Robotiques) and one of the study’s authors. The robot is seven centimeters long — longer than the fish it’s modeled after, but with the same shape and proportions. It’s equipped with magnets that link it to a tiny engine installed under the aquarium to propel it through the water. The researchers chose zebrafish — or Danio rerio — for their study because it’s a robust species whose schools tend to switch direction and move about very quickly.The robot has two parts: a magnetic fish; and a motor which is positioned underneath the aquarium and helps propel the robot through the water. To infiltrate the school, the EPFL team identified characteristics that real fish use to distinguish themselves and designed the robot accordingly. These included physical traits (such as shape, color, and markings) and behavioral traits (including acceleration speeds, size of schools, and how the fish move their tails in transit). Taking the project one step further, the researchers designed the robot to learn and adapt from the behavior of the real fish.
DOES THIS REGISTER? Remember back when you could fly drones without having to pay the government money first, and when the only thing you had to worry about was a midair takedown by an anti-drone hit squad made up of highly-trained Dutch eagles? We’re sad to have to report that we probably won’t be seeing compelling videos of eagles handling rogue drones anymore (https://spectrum.ieee.org/ automaton/robotics/drones/dutch-police-training-eagles-to-take-downdrones), and also that the United States government has flexed its muscles, and mandatory drone registration is now back on. This means that the drone that you didn’t have to register and then had to register and then didn’t have to register, you now have to register.
14
SERVO 02.2018
Bots in Brief - Feb 18_Bots in Brief Mar15.qxd 1/3/2018 1:15 PM Page 15
bots
IN BRIEF CAN YOU SEE ME NOW?
Most telepresence robots are designed for business use. They’re expensive, but the argument is that they work significantly better than a phone call, and they pay for themselves since you don’t have to spend so much time and money traveling instead. OhmniLabs, a Silicon Valley robotics startup with CMU roots, wants to make telepresence robots easy and affordable enough that people start using them to stay connected with their families. In order for that to work, their telepresence robot called Ohmni is designed to be as independent as possible. You can send it to someone who isn’t comfortable at all with tech, and they can take it out of the box, turn it on, and it’ll just work. It’s potentially ideal for family members who you don’t live close to, or elderly family members who you like to talk to (and check up on) regularly.
FLAME ON, HUBO! One of the traditions of the Olympics is the torch relay, in which people carry the flame from Olympia, Greece to the location of the Games. In 2018, the Olympic Games will be held in Pyeongchang, South Korea, and the torch relay is currently underway. HUBO, the humanoid robot, carried the flame for part of its journey. HUBO only covered 150 meters (about 500 feet) with the torch, but its presence was largely symbolic. As part of its torch duties, HUBO performed an example of a disaster rescue operation in which it cut a hole in a brick wall (while still holding the torch). It was intended as a "display of innovation and creativity," according to PyeongChang 2018 Organizing Committee President LEE Hee-beom. Okay, maybe it's a little silly — especially considering it was largely a stunt — but it doesn't change the fact that HUBO is Korea's first humanoid robot and what it accomplished was pretty darn cool. It has two articulated hands and can walk 65 steps per minute. It's being designed as a first-responder robot (hence, the display of its abilities). It will be interesting to see how it develops from here, but for now, we know that HUBO is quite capable of participating in stunt demonstrations at least.
SERVO 02.2018
15
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 16
SPARC Getting Started Guide Standardized Procedures for the Advancement of Robotic Combat ● by Mike Jeffries
Before You Build Your First Bot aybe you’ve seen BattleBots™, been to RoboGames or other local events, seen video on the Internet, or read event reports right here in SERVO Magazine. Whatever the source, you’ve decided that you want to build a bot. At this point, you may be asking yourself a very important question: Where do I start?
M
Well, this guide will help you find your way inside the arena.
Finding an Event One of — if not the — first step
Featured This Month: SPARC GETTING STARTED GUIDE 16 Before You Build Your First Bot
18 Component Selection
21 Weapon Systems 25 Custom Fabrication
26 Packing for an Event
29 What to Expect at an Event
16
SERVO 02.2018
you should take is to figure out where you’ll be competing. For those that have been to an event, you probably have an idea where to look. If you’ve never been to an event, however, you may not even know where to start. In general, event information is readily available online through a range of sources. In the US, the following URLs are your best bet when looking for an event:
• https://www.robotcombat events.com/ • http://robotbattles.com
In the UK, the best source for upcoming event information is www.fightingrobots.co.uk. In Australia, the best source for upcoming event information is www.robowars.org/forum. Beyond being a source for event information, the vast majority of the robot combat community online can • http://sparc.tools/ be found spread between the SPARC • www.buildersdb.com Forum, the Facebook Robotics • https://www.facebook.com/ Community, FightingRobots.co.uk groups/RobotCombat/ (The Fighting Robots Association), and Robowars.org (RoboWars Australia). These groups will be a great resource both for getting questions answered and seeing how other people have answered many of the design questions you’re trying to address. Once you’ve found an event you There’s a big difference between fighting in a fully want to attend, the enclosed arena … next step is to read through the rules. While many events ... and fighting on a stage. have the same rules across all the weight classes, some events will have different rules for different weight classes which may influence which class you decide to start with. While not necessary, at this point it would be a
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 17
To post comments on this article and find any associated files and/or downloads, go to www.servomagazine.com/index.php/magazine/issue/2018/02.
COMBAT ZONE
good idea to attempt to find video from previous years of the event you’re planning to attend. This will give you a good idea of the sort of machines you’ll be fighting, and the unique quirks of the environment you’ll be fighting in.
bot, there may be a large number of one-off parts that will be difficult to replace, and there is the potential for worn or damaged components that are not initially obvious. If you’re considering buying a used robot, it would be wise to ask an experienced builder whether or not it would be a good fit for your needs. In both cases, the biggest thing you miss out on by buying a completed robot You’ve now got enough is that you won’t learn nearly information to start figuring as much in the process of Sometimes robots you design and build yourself out what you want your first getting a bot into the arena. work well. bot to be. The next decision to Taking time once you be made is whether have the robot in you want to start your possession to with a kit, design and go through all of build it yourself, or the systems and buy a ready-to-run familiarize yourself bot. with the From a learning components and standpoint, designing layout will help and building your offset some of this, own machine is likely and make it much Sometimes they don’t. the best option. Building your own easier to diagnose and repair any machine is also the most difficult problems that occur during an event. choice — especially if you have limited shipping. You may also find robots for Buying an unassembled kit is tool access. If you go this route, sale on any of the robotics community effectively the intermediate option. looking through past build reports in sites or from several of the advertisers While you’ll learn more building one SERVO and online will be a great in this magazine. yourself, you will still learn a great means of learning from the mistakes The pros of buying a ready-to-run deal putting the kit together. Plus, you of others, and possibly picking up robot are pretty obvious: You know it know that if you do it right, once it’s tricks to get better results out of the works, you can likely find tools you have. video of the bot (or the A good option would be getting same kit in the case of actively involved in the online kits) in action which will communities and if one is available, often show the strengths go to the local robot club to talk with and weaknesses of the other builders about what you want design before you buy to do. The best thing you can do anything; and it’s a fairly during this process is ask questions quick way to go from and really listen. Every builder was nothing to a working new once, and most are happy to robot. offer advice when asked. In the case of a preHypnus is a 12 lb combat robot The easy option is to buy a robot built kit, you’ll be paying that was recently that’s ready to run. Some kit sites like a good deal more than if sold on eBay. Kitbots.com offer the option of you had built the same having the kit fully assembled prior to kit yourself. With a used
To Kit, or Not to Kit
SERVO 02.2018
17
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 18
together you’ll have a machine that you know will work. If you’re looking for a kit in the 150g-3 lb range, there are a large number of options to choose from. Kit vendors focused on this weight range include but are not limited to:
For large kits, there aren’t as many options; www.gearseds.com offers kits focused on the 15 lb educational class and www.battlekits.com sells kits focused on the 60-220 lb classes. In the end, whatever method gets you to an event and competing is the best approach. There’s no substitute for the experience you’ll gain by actually participating an event. SV
www.fingertechrobotics.com www.kitbots.com www.botbitz.com www.shockbots.co.uk https://www.botkits.com/ Klazo is a lightly modified 1 lb robot kit from Kitbots.com.
Component Selection lot goes into a bot. Starting out, it can be overwhelming trying to figure out what you need to get to make a working robot, where to go to get the parts you need, or how to put it all together. This section of the SPARC Getting Started Guide is meant to address all those issues.
A
Radio System When selecting a radio system, the first thing you must do is confirm that the system will failsafe on all used channels. Failsafe means that if the signal to the receiver is lost, all drive and weapon systems will return to a non-active state. Any system incapable of this function will not be allowed to pass safety. The 2.4 GHz radio systems are increasingly common and often required at events. There are a wide range of products available that meet the failsafe requirements and 2.4 GHz suggestion. If you’re not sure that a system will failsafe properly, ask the merchant or manufacturer. The Robot Marketplace often will list if a system or component will failsafe properly on the product description.
18
SERVO 02.2018
Kill Switches Commercial Switches Being able to safely turn your robot on and off is another requirement to compete. The Whyachi MS-XX series and the Hella switch are two good commercial options for large bots. For smaller robots, FingerTech Robotics has a power switch that works very well in the 150 g-12 lb class that has been used in bots up to 120 lbs. BotBitz also sells an extremely small switch designed for the 150 g-1 lb classes. Homemade In addition to commercial switches, there are some styles of power switches that can be made at home. The most common involves using a plug to add a removable loop of wire between the battery and motor controllers. Using this method means you will physically remove part of the circuit to power-off the robot.
Motor Control There are several methods commonly used to control electric motors in robot combat. For full
proportional speed control, an electronic speed controller (ESC) is generally the most reliable option. There are a wide range of ESCs available for robots ranging from 150 g to 220 lb. The key is to find a controller that is rated for your desired voltage or higher, and can handle the current draw of the motors. The torque/AH calculator at www.killerbotics.com/kbtools/Tent acleTools has many common drive motors and can be used to estimate stall and wheel spin amperage. For motors that only need on/off functionality, contactors/DC solenoids can be used in conjunction with RC switches for more power handling capabilities at the cost of precise control.
Motor Selection There are two main types of motors available: brushed and brushless. Brushed DC motors have been used in robot combat since the beginning. They’re a bit bulky, spin at relatively low RPM, and have great starting torque making them ideal for drive systems. Brushless motors have recently become the go-to option for high
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 19
COMBAT ZONE powered weapon (and occasionally drive) systems. Brushless motors tend to have a higher power-to-weight ratio and much higher RPM, but often suffer from “cogging” when geared with low reduction and heavy attachments. Cogging means instead of smoothly accelerating, the motor sputters and often stops. The simplified version of why this happens is the large mass relative to the torque of the motor results in the controller and motor getting out of sync preventing proper acceleration. In weapons, this can result in slow or no spin-up, and in drive systems it can result in erratic low speed behavior. Brushless drive systems are less common as there are not many controllers available that give quick proportional forward and reverse control, and the high RPMs can make gearing systems more difficult than with brushed motors. However, some teams have found success pairing brushless motors with gearboxes designed for brushed motors.
Common Drive Systems For a first build, wheels with tank style steering are the simplest option. Tracks and walking systems can be built, but on your first build, getting something working reliably should be the focus. The two main wheeled options are two-wheel drive and anything greater than that — usually in multiples of two. Two-wheel drive robots will have two powered points of contact with the ground, and short of a balancing robot, this means at least one nonpowered point of contact will exist. This can either be a piece of chassis/armor dragging on the ground, a skid, or a caster. The best option will depend on the exact design of the robot and what arena it will compete in. Robots with greater than two
driven wheels will likely have all points of contact with the ground powered with the exception of hinged components that are meant to stay in constant contact with the ground.
Chassis Construction Chassis construction generally takes one of a few different routes. The first is an internal frame with armor attached to it; the second uses the frame members as armor, often with connected plates of material forming the structure; and the third is unibody construction, where the majority of the frame and armor are cut from a single piece of material. Building a chassis using an internal frame with armor panels mounted to it tends to be the heaviest of the three options, though often will be the most durable and easiest to repair as the portions of the armor most likely to be damaged are easier to remove from the rest of the robot. These frames typically involve a welded frame with armor bolted to it. Frame as armor construction is generally in the middle when looking at strength vs. weight. By reducing the frame and armor into a single part, you can reduce the size of the machine and use relatively thick materials in areas likely to come into contact with weapons. Frames like this are usually bolted together. Unibody construction will typically be the strongest per pound. However, it’s also the most complicated to manufacture, as all features will need to be added to a single piece of material. This often involves repositioning the workpiece many times during the construction process. Care must be taken to avoid misalignment of holes as the workpiece is moved. The good strength-to-weight ratio — the best of the three mentioned — is due to the reduced need for fasteners to hold the chassis together, and the lack of areas only held on by hardware.
Common Construction Materials Metals While there are many different types of commercially available metals on the market, there are only a few that are well-suited to robot combat. The four primary metal types used in robot combat are steel, titanium, aluminum, and magnesium. For each type of metal, there is an alloy or set of alloys that find common usage since the mechanical properties of the alloy are a better match for combat use. • Steel: Steel comes in a huge range of alloys and can have its properties dramatically altered by heat treating and tempering. That being said, steel will likely be the toughest armor option for a given shape. However, it will also be the heaviest option. Steel is frequently used for weapons since high grade steels can be heat treated to achieve a nice balance of stiffness and strength while not being so brittle that they will readily shatter. Common steels in robot combat are 4130, 4140, 1095, and S7. There are many other steel options out there, and often you can find a specific alloy that is well-suited to your application. • Titanium: Titanium is a fantastic material if you’ve got the budget and the necessary tools. Grade 5 titanium provides a great balance of light weight and strength at the cost of being difficult to work with and expensive. • Aluminum: Aluminum is a fairly light metal that’s easy to work with and isn’t too expensive. There are many grades of aluminum available, but 6061, 2024, and 7075 are the most common in robot combat applications. • Magnesium: Magnesium is the lightest metal listed here. Magnesium is fairly easy to machine, but heat control is a must as it burns energetically if it’s allowed to get hot SERVO 02.2018
19
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 20
enough. AZ31B magnesium has a higher tensile strength than aluminum, which makes it a great material for armor if you can afford the cost which rivals titanium. Plastics There is a wide range of plastic materials available, and an entire guide could be written on them. The most common plastics in robot combat are polycarbonate, nylon, UHMW polyethylene, and Delrin. • Polycarbonate: This plastic is also known as Lexan and is the material used for arena walls. It once was a very common construction material due to its impact resistance, however, it’s prone to fracturing at hole locations and has become less common in recent years. It’s still a fantastic option for energy absorbing panels, but you’ll need to minimize the number of holes and make sure it’s shock mounted as the polycarbonate needs room to flex to work properly. • Nylon: Nylon is a relatively rigid plastic with a high tensile strength. It’s most commonly used as an internal structural member. Nylon is also one of the more durable economical options for 3D printed components. While 3D printing of metals is possible, it’s still prohibitively expensive for most uses. Printed nylon parts are relatively cheap and easy to get. Look for variations on “strong and flexible” when looking for printed nylon. • UHMW Polyethylene: UHMW has become one of the more popular construction materials. While relatively low strength, it has proven to be an extremely durable construction material and is frequently used both as armor and for main structural elements on robots. The light weight allows a large amount of material to be used, so this results in a very tough frame member that is capable of absorbing a good deal of damage. UHMW also has a fairly low coefficient of friction, so is often seen
20
SERVO 02.2018
used as skids or as bushing material. • Acetal Delrin: Delrin — like nylon — is a fairly high strength plastic. It holds its shape well and is fairly easy to work with. Delrin is also relatively heat resistant which means you’ll often see it used in applications where heat is expected. A few common uses for Delrin are wheel hubs and the bodies of power switches.
Composites Composite materials come in two forms: pre-made parts and raw fabric. The pre-made parts are often used as armor panels when weight is a serious concern. When used properly, they can be as good as some metals. Their limitations must be kept in mind, however. Different composites will have specific types of applications they are good for. Some are better in tension and some are better in compression. This is due to what the composite is made of. The parts — commercial or DIY — are a mix of a fabric (Kevlar, carbon fiber, fiberglass, etc.) and a resin. The fabrics generally perform well in tension, regularly exceeding the tensile strength of popular metals; the resin handles the compressive loads.
Batteries Lithium Polymer Lithium Polymer (LiPo) batteries are becoming the go-to battery option for most weight classes. These batteries provide the highest energy density of all battery types that are commercially available. The downside to LiPo batteries is that they deal with damage poorly. There have been several incidents where a LiPo battery taking damage has resulted in a spectacular fire. If you’re planning to use LiPo batteries, be sure to consider how you’ll protect them from damage as a battery fire will likely ruin most of the parts near the battery.
LiPo batteries also tend to swell under heavy loading, so using padded elements in your battery mounts can help minimize the risk of damage when this swelling occurs. Lithium Ferrite Lithium Ferrite (LiFe) batteries are another common battery type. This chemistry does not provide the same energy density of LiPo batteries. However, it’s still a substantial improvement over NiMh, NiCad, and SLA batteries. LiFe batteries are also less reactive to damage which means (unlike LiPo batteries) there are no major events that restrict the use of LiFe batteries. NiMh/NiCad Nickel Metal Hydride and Nickel Cadmium batteries have fallen out of favor in recent years as LiPo and LiFe batteries have become available. These chemistries were the go-to option for years in the smaller weight classes. You may be able to get these batteries for less cost than LiFe and LiPo packs, but the price difference is shrinking quickly and the massive weight increase for the same power output makes them a less than ideal option for a new bot. SLA Sealed Lead Acid batteries are still seen in the heavier weight classes. These batteries are heavy, but they’re generally quite stable and can handle putting out large amounts of current without issue. SLA batteries are mostly worth consideration for robots weighing 60 lbs or more. SV
Major Vendors www.botbitz.com www.e0designs.com www.fingertechrobotics.com www.kitbots.com www.robotmarketplace.com www.robotpower.com www.servocity.com www.ttrobotics.com
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 21
COMBAT ZONE
Weapon Systems he sport is called robot combat, so it’s inevitable that weapon systems will be discussed. The weapon types commonly found on fighting robots can be broken out into two major categories: non-kinetic energy weapons and kinetic energy weapons. Non-kinetic energy weapons are generally more focused on control of the opponent over outright damage, though these systems can and do often cause serious damage. Kinetic energy weapons use the high speed movement of either the entire robot or a subsystem of it to cause damage. While non-kinetic energy weapons may sound safer, all of these weapon types can be dangerous and should be treated with respect.
T
Non-Kinetic Energy Weapons Rammer Ramming robots are the most basic design in robot combat. A ramming robot relies purely on strength and power for success. Ramming robots often incorporate spikes or heavy chunks of metal on the front of the robot. Spikes on a ramming robot are normally intended to penetrate the armor of the opposing robot. Ramming robots with simple metal
chunks on the front use their drive power to send their opponents into the walls or any hazards in the arena. Strong rammers are sometimes capable of breaking spinning weapons. They all have one thing in common: they are very hard to immobilize. They are often invertible, durable, and have powerful drive systems.
Rammer. Photo courtesy of Michael Mauldin.
Wedge Wedge robots are similar to ramming robots. They share the need for a powerful drive system, a strong chassis, and good armor. Wedge robots are among the most common types used in robot combat today. Many robot builders incorporate a wedge of some sort into their design. For some, it’s the backup plan if the weapon fails. For other robots, the wedge acts as part of the weapon — be it leading into spinning blades or a hiding place for a powerful lifting arm. These robots are all about mechanical advantage. They get under their opponents and use their drive power to flip or shove them at high speeds into an obstacle like a rammer.
Lifter. Photo courtesy of Jim Smentowski / RobotCombat.com.
Lifter Lifting robots can be viewed as the next step up from a wedge robot. They perform essentially the same function. They both make the drive system of the other robot ineffective. There are a few different methods of constructing lifting arms.
Wedge. Photo courtesy of David Weston.
Lifter. Photo courtesy of Chad New.
The most basic is pushing or rotating a single hinged piece of metal. It’s very effective in its simplicity. For this style of lifting arm, linear actuators are often used. Linear actuators act like pneumatic pistons, but slower and often in a lighter package. Another popular lifting system uses a four-bar linkage. This system allows the bar to lift and push at the same time. It also lets the arm tuck nicely back into a flat chassis. This SERVO 02.2018
21
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 22
Flipping robots normally use opponent vertically and often spinning pneumatics to power their into the air. arms due to the high flow Grabber rates achievable in Grabbing robots are a variation pneumatic systems. of the basic lifter. Grabbing robots use Pneumatics can be used in some sort of device to get a hold of any lifting system that can their opponent which allows them to be operated by an extending manipulate the opposing robot in rod. ways that other types are not able to. Flipping robots are able While some grabbing robots do not to throw their opponents use a lifting mechanism in conjunction into the air, possibly with their grabbing mechanism, the dislodging vital components two work together well. or causing them to land in a Most arenas used today do not manner that would prevent Flipper. Photo courtesy of Will Thomas. have dangerous hazards in them, but them from driving. grabbers could still be used to remove Flipping mechanisms Crusher. Photo courtesy your opponent from a match by normally require more of Josh Zimmerman. putting them over an arena barrier or weight than a lifter, as into a pit. more power is needed Grabbers are a good option to send a robot into the against many opponents in the right air than to tip it. arena. They do have one major A prominent weakness, however. If they face a flipping system in robot with a spinning weapon European robots has the mounted in an area the grabber tries piston attached to a to pass through, there is a very good hinged plate that fires chance that their grabbing mechanism system has proven extremely effective out of a wedge shaped chassis. The will be forcefully removed from the when built properly. plate is hinged at the bottom, which rest of the robot, making its primary Some lifters drive the arms with causes the swing of the plate to not mode of combat inoperable. an electric motor. With that system, only lift the opponent but toss it away the arm is attached to a rotating from the flipper robot. shaft. The shaft has a sprocket or gear Crusher Another common flipping arm is on it which is driven by an electric Crushing weapons can be very hinged at the back of the bot. It motor. These systems require heavy devastating when used properly. They extends to the front, and then bends gear reduction to be effective. aren’t nearly as common as spinning down to meet the ground with some Hydraulic lifting arms have or flipping weapons, but are on par means of getting under another robot sometimes been used, but are attached. The uncommon in combat robotics. They pneumatic piston is are usually too heavy and slow for either mounted most applications of this nature. vertically or in a Hydraulics are best suited for systems position that when that require large amounts of torque the piston has and not much speed. reached maximum Lifting arms require a very strong extension, it will be drive and chassis system to be vertical. effective. If it cannot take the abuse a This reduces the more aggressive weapon can deliver loss of force due to while the lifter is trying to get under leverage some other its opponent, it will not be successful. systems have, allowing for a very Flipper powerful throw. Flipping robots are essentially These flipping arms Grabber. Photo courtesy of Charles Guan. lifters run at much higher speeds. tend to throw the
22
SERVO 02.2018
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 23
COMBAT ZONE with them when you look at damage potential and combat effectiveness. Crushing arms are normally powered by hydraulic systems or high torque linear actuators. They tend to be slow, but extremely powerful. The goal of a crusher is to penetrate the armor of its opponent and dig the arm into some vital component. Even if after achieving penetration nothing vital was hit, they still have a very firm grasp on their opponent. They can take them into any arena hazards or just drive them into a wall. An effective crushing robot needs to have an agile drive system, a solid chassis, and a strong arm. Due to the nature of the crushing robot, it needs to be able to get to the weak points on its opponents to be effective. The forces that are put into the chassis by the crushing arm are enough to warp a weak frame. A solid frame for the area that this force is transmitted into is vital.
Kinetic Energy Weapons Hammer Hammer robots have many options when determining how to operate their weapon. Several different power sources are capable of powering an effective hammer. The most basic method of actuating a hammer is to directly attach the piston to the hammer arm. This system makes it difficult to get a
Thwack. Photo courtesy of Ilya Polyakov.
large swing angle, but allows for a light weapon drive. This method has been used on many top hammer robots. The simplicity of this system makes it an easy design to start with. Rack and pinion hammer systems are somewhat heavier, but have a major advantage. These hammers can swing 180 degrees or more. The only rotational limit is the rack and pinion Hammer. Photo courtesy of Al Kindle. setup itself and the stroke of the piston pulling the Vertical Spinner. rack. Adjustment of Photo courtesy the gears in the rack of Orion Beach. allows for precise control of the arm’s swing. Spring fired hammers use powerful coiled springs to shoot the hammer downward onto the opponent, then a heavily geared-down electric motor to retract the hammer and ready it for the next swing. The horizontal thwack bots are more spring can generate a great amount common as they tend to be easier to of power, but this weapon system is make. much slower than many of the other Overhead thwack designs have options for powering a hammer the entire main body of the robot weapon. rotate with the hammer. This means Running the hammer directly off that the majority of the mass must be a motor is a simple method for contained within the diameter of the making a hammer robot. Many of wheels. The striking object tends to be light because a heavy weapon these systems are chain driven would be much harder to flip over the to achieve the proper speed and reduce the stress on the top of the robot. shaft of the motor driving it. Properly balancing the rotating Motor driven hammers tend to body of the robot is essential to be fast but not as powerful as getting a good swing. Swinging the pneumatic hammers. weapon is achieved by quickly reversing the direction of travel and using that torque to rotate the body Thwack 180 degrees. There are two types of The other type of thwack robot ‘thwack’ bots. One is a spins its entire body horizontally to horizontal thwack robot. The cause damage. The impact points on other is an overhead thwack the robot can be connected directly to version. Both types have been the body of the robot or a mass can effective in combat, but SERVO 02.2018
23
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 24
to one side. You risk either flipping over or losing traction as the wheels are lifted off the ground. The hazard here is that when you are doing this, the other robot is able to better position itself for a counter attack. Vertical spinners tend to have wide drive systems to counteract this force. Drum/Beater. Photo courtesy of David Moulds.
be attached to the end of a pole. Both methods have been effective in the past. The main difficulty with this design is that translational movement while the weapon is active is difficult. There are solutions to this, though. Most systems that attempt to fix this problem rapidly adjust the speed of individual wheels to cause it to slowly move in the desired direction.
Drum/Beater Drum weapons are the cousin of the vertical disk. Unlike vertical disks, drums tend to have a fairly small diameter. They are also normally very wide, often covering the majority of one side of a robot. Gyroscopic forces become less of an issue with the drum design. They also have a much wider impact area. Drums are often spun at a higher RPM than other spinners. Drum robots don’t rely on one big hit. Drums are meant to get to speed quickly and hit many times in rapid succession. A common drum variant referred to as an ‘eggbeater’ removes the drum portion of the design, using just the impact bars and supports in the structure of the weapon.
Vertical Spinner Vertical spinners mostly come in two varieties: bar and disk. Both do basically the same thing. The idea with a vertical spinner is to use the ground to your advantage. When a spinning object hits a robot, half the energy goes to each robot. Vertical disks use the ground to Horizontal Spinner absorb that energy while the The horizontal spinner is a wide opponent only has its weight to resist category. It includes shell spinners, the force. overhead spinners, front mounted Vertical spinners require a lot of spinners, and undercutters. strength in the frame that supports the weapon to Horizontal Spinner. avoid damage during Photo courtesy of impacts. Many vertical Ray Billings. spinners have a support going down from the shaft of the spinning disk to help absorb the impact. Vertical spinners are prone to gyroscopic issues when turning. If you try to turn too quickly with a vertical spinner, it may tip
24
SERVO 02.2018
Shell spinners have a rotating mass that surrounds the chassis of the robot. These spinners develop a high amount of kinetic energy when spinning due to the large mass of the spinning object. The shells also double as kinetic armor when the weapon is operational. Shell spinners are most effective when the shell is short in height. A low center of gravity keeps them stable after powerful impacts. Overhead spinners normally use bars. This weapon is not as powerful as a shell spinner, but it’s easier to build and weighs less. The weight savings allows for a stronger drive system or frame. The simplicity makes it an easier project for a new robot builder. These weapons — when used right — can be extremely effective. Front mounted spinning weapons are almost identical to overhead spinners. Instead of having the blade on the top of the robot, it’s mounted into a frame that comes out one side of the bot. This allows the blade to be lower to the ground, and the robot that wields it to be taller without losing effectiveness. Undercutters do just what the name implies. The idea with this weapon is to remove the wheels and anything else sticking out the bottom of the opposing robot. Undercutter blades ride close to the ground which makes them difficult to avoid in a match. The blades often have a material beneath the bar to prevent them from hitting the arena floor. All horizontal spinners have problems with over- and under-steering. When you spin a large mass at a high velocity, it causes the chassis to want to rotate. The rotation of the weapon will cause the robot to turn much faster in one direction and have trouble turning in the other. It will also have some difficulties driving in a straight line. SV
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 25
COMBAT ZONE
Custom Fabrication hen it comes to building robots, there’s a lot on the market today. So much of what you need can be ordered with little to no hassle. That being said, when building a robot you may come across specific parts or assemblies where you can’t order it and don’t have the equipment or resources to do it yourself. This isn’t a huge barrier though, because in addition to potentially working with local shops to get custom parts made, there are a lot of good options for custom combat robot parts to be found online.
W
Team Tiki Robotics http://ttrobotics.com Major Equipment: CNC Mill Team Tiki is a small outfit that has only recently started offering machining services to the robot combat community. The relatively small equipment list means that Team Tiki won’t always be able to make the parts you’re looking for, but if it’s something they can make you can be sure you’ll be getting high quality parts at good prices. Beyond custom machined parts, Team Tiki is also the primary US distributor for BotBitz ESCs and their own Beetleweight sized gearmotors. Team Whyachi Bot Shop http://teamwhyachi.com/botshop. htm Major Equipment: CNC Mill, Lathe, Waterjet, and Welding The Team Whyachi Bot Shop is effectively a one-stop place for highend fabrication. They’ve got the equipment and abilities to make almost any part you could realistically want for your robot. One downside is they don’t quote pricing, so you’ll need to know what you’re asking them for or else you may be in for a surprise when you get sent the bill. That being said, if you’ve got complex
parts, the Team Whyachi Bot Shop is likely to be your best option. In addition to their machining services, Team Whyachi also sells high quality gearboxes, wheels, and power switches. Big Blue Saw www.bigbluesaw.com Major Equipment: Waterjet and Laser Cutting Big Blue Saw does a few specific things and it does them Shaped titanium wedge, magnesium top plate, and 6061 frame all fabricated by very well. If you need parts with a Team Whyachi. two-dimensional profile cut out of a wide range of materials and you don’t want to wait to find out what it will cost you, they’re the place to get them. The best thing about Big Blue Saw is that they offer instant quotes for Steel weapons for an Antweight made by Team Tiki. a huge range of stock Reducing the number of different materials, so you’re not stuck waiting sheets of material your parts need to and wondering what you’ve just be cut from can dramatically reduce spent. If the material or thickness you the per-part cost of your machine. want isn’t in stock, you can contact them directly for pricing. One thing to keep in mind if eMachineShop you’re trying to keep costs down, with www.emachineshop.com waterjet cutting, setup time is a big Major Equipment: Huge range of part of the cost on small part runs. capabilities eMachineShop functions similarly to Big Blue Saw in that you can quickly get pricing on a range of custom parts. eMachineShop has their own free CAD program which is used for modelling and quoting 2D or 3D parts. eMachineShop isn’t likely to be the cheapest option on the market, but it’s a good way to get parts made without any guesswork on what they’ll cost you. Waterjet cut custom heatsink made from 1/2” thick aluminum by Big Blue Saw.
Shapeways www.shapeways.com Major Equipment: 3D Printing 3D printed components have become very popular in the small bot SERVO 02.2018
25
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:11 PM Page 26
FDM parts is that due to how these parts are printed, they will be weaker in some axes due to the printing method as the bond Aluminum weapon hubs made via MFG.com. between layers create an account; put up a quote isn’t as strong as the material request for one, all, or any itself. This means that A 150g robot with printed sintered nylon chassis combination in between of the parts components that are from Shapeways. you want to have made with general stressed will be more likely to classes, and one of the easiest sources info and drawings/CAD files; then you fail along a shear layer. for one of the tougher material get quotes from shops all over the Accommodating for this weakness can options is Shapeways. Their “Strong & country or the world who are greatly reduce the risks in functional Flexible” plastics are laser sintered interested in making your parts. parts. MFG.com has been used by nylon which is one of the tougher printed plastics available right now. MFG.com many builders with a good deal of In addition to plastics, Shapeways www.mfg.com success. However, as you’re dealing with a specific shop, once the work also can print steel, brass, and bronze Major Equipment: Almost anything begins you do need to proceed with if you want to go with printed metal MFG.com isn’t a single shop. It’s some degree of caution until you’ve components. If you’re feeling a way to find shops that can make the built up a relationship with that particularly hands-on, they’ll also print parts you want. With MFG.com, you parts out of castable wax which specific shop. A more detailed review would make it possible to design of MFG.com can be found in the July difficult-to-machine parts and cast 2013 issue of SERVO. them out of solid metal. Between the six resources mentioned here, you should be able i.Materialise to find someone that can make just http://i.materialise.com about anything you’d want for your Major Equipment: 3D Printing robot. In the cases of Team Tiki, Team i.Materialise also offers a range of Whyachi, and Big Blue Saw, they’re 3D printing options, from FDM also involved in robot combat and printed ABS (similar to how many home 3D printers operate) to sintered have supported events throughout the titanium parts. years. SV FDM printed model of a 30 lb fighting robot. One thing to keep in mind with
Packing for an Event our robot is (hopefully) done, so it’s time to pack your bags and make your way to the event. While it would be handy, there are quite a few impracticalities to bringing all your tools and equipment with you. This means you’ll need to pack a selection that at least should be enough to get you through the event without spending too much time
Y 26
SERVO 02.2018
scrambling for tools and borrowing other team’s gear. We won’t be talking about tools that are particularly specialized. If your machine needs any specific equipment for basic maintenance and repairs, those take priority. The following sections will cover tools that are almost universally useful in the pits during an event.
The Bare Essentials This section covers the smaller equipment that should be easily crammed into a relatively small toolbox. Improvised Repair Kit At events, sometimes you’ll end up with damage that isn’t able to be
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:12 PM Page 27
COMBAT ZONE properly repaired with the tools and materials you’ve got available. Having a selection of the following items can help make the best of a bad situation: • Hot Glue Gun • Epoxy • Super Glue™ • Zip Ties • Duct Tape • Goop/Shoe Goo/E-6000 silicone adhesive • Velcro™ • Electrical Tape Hex Keys
Most robots will have at least a few fasteners in them that need a hex key. Keep a nice set together so you don’t spend half your repair time searching for the right sized key. In general, the T handle style hex keys are more comfortable to use. However, it’s highly likely that you’ll run into situations where you’ll need the shorter profile provided by L shaped keys. In addition to this, many commercially available power switches use hex keys for operation. For power switch activation, either a T handle or screwdriver style hex key is a good option as they are available in long lengths which keeps your hands away from the robot during power-up. If possible, add a layer of heat shrink tubing to the majority of the key length to insulate it from the chassis and differentiate it from the rest of your keys. If you’re looking for the luxury option when it comes to L shaped hex
keys, look at the inch and metric Wiha ErgoStar keys (www.wihatools.com/600seri/669C hrom_mm.htm). They’re a bit pricy as far as hex keys go, but they’re a good quality steel and the case design makes it much easier to remove just the key you want. Locking Pliers A good set of locking pliers can be fairly versatile at an event. When paired with a vise or immovable slotted object, they can quickly aid in the de-bending of damaged armor. If you strip the head of a screw, a few flats ground into it and you can use these to break it loose. If you’re hammering something flat, these move your fingers farther from the hammer. For such a basic tool, they’re quite versatile and won’t take up much space in the toolbox. There are a ton of options on the market to choose from. A traditional curved jaw plier will probably serve you better than a needle-nose in most general applications. So, if you’re in a spot where you have to choose one over the other, that is where to start. MultiTool
the right tool, but are often good enough to get the job done when you don’t have the right tool handy. Small Hammer
A small hammer can do quite a lot in a small package. If you can find one, the ideal hammer for this purpose is fairly light, has interchangeable heads (often nylon, brass, or steel), and will normally be less than 12” long. The softer faces on this hammer allow for quite a bit of energy transfer while not doing much (if any) damage to the surface of the material you’re hitting. This is particularly useful when flattening bent armor panels or pounding down gouged areas. If you’re searching for one of these online, a search that turns up quite a few results is “interchangeable head hammer.” Wire Strippers It’s tough to predict when you’ll need them, but at some point, you’ll need a set of wire strippers in the pits
Exactly what you get here depends on the model, but you’ll normally get at least a set of needlenose pliers, wire cutters, wire strippers, a knife, and a screwdriver. In most tasks, it’s not as good as the tool it’s replicating. However, it makes for a compact way of having a spare of each of them. Multitools are rarely SERVO 02.2018
27
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:12 PM Page 28
at an event. If you don’t already have a pair, it won’t be expensive to get a decent small one for your toolbox.
abrasive discs allow for shafts to be quickly cut down, lightening slots to be cut, stripped screws to be slotted, and wedges to be sharpened.
Wire Snips Sliding Clamps
at the last minute and won’t have gotten around to checking the weight until the day of the event. Whether it’s you or someone else in this position, having a drill handy is a decent method of dealing with the problem. Cordless Impact Driver If you manage to make it toward the end of the bracket at an event, time starts getting quite tight. An impact driver combined with a bit set can dramatically speed up the removal and reinstallation of access panels between matches. Angle Grinder
While having wire snips and strippers may seem redundant, often wire strippers have the cutter deep within the jaws of the stripper. The snips are only meant for cutting, which means if you need to quickly extract some piece of electronics you won’t be stuck trying to cut it out with a knife or awkwardly fumbling with wire strippers. These are also quite handy for quickly removing zip ties if you use them to keep the wiring in your machine in order. Adjustable Wrench If you can fit a full wrench set in your box, go for it. If not, an adjustable wrench is almost as good and takes up far less space. Even if you’ve managed to not use nuts anywhere on your machine, it can still come in handy as an additional debending or prying tool. Soldering Iron If you end up having to do much of any electrical repair at an event, you’re almost certainly sunk without one of these. Rotary Tool There’s a good chance you’ve got one of these already, and you already know how useful they are. The
28
SERVO 02.2018
Whether you’re using them to hold parts in place while you’re debending them, using them as a weapon lock on a small robot (do test to make sure it will actually stop the weapon before assuming it’s capable), or just using them as an extra hand in the pits, these things always come in handy. If you can fit it, pack a few in different sizes. 1/4” Bit Set and Driver A good bit set will make sure you’ve almost always got the screwdriver head on hand that you need. If you use the case, you’ll have them all relatively neatly organized in one spot, so when you need them you won’t waste time digging.
If you have more room for tools than just a small toolbox, there are quite a few handy things that you can bring with you. In general, these will allow for faster modifications or repairs during an event.
If you absolutely need to grind it flat, cut it off, or shave it down now, an angle grinder is the tool to use. You can get a wide range of wheels for them with grinding, cutting, or sanding as the primary focus, and when used properly it can do the job a rotary tool would do in a fraction of the time. Just be careful with where the sparks or dust gets sprayed. Whenever possible, make sure to cover any openings into your machine with tape or similar to reduce the chances of metal shavings getting in and shorting something.
Cordless Drill The big use of a cordless drill at an event is removing weight at the last minute. It’s almost inevitable that someone will have finished their robot
Large Hammer As with the angle grinder, a large hammer will often do the same job as the similar small tool but much faster. A large sledge or demolition hammer
Luxury Items
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/3/2018 4:12 PM Page 29
COMBAT ZONE should be a tool of last resort, but when it is needed to fix the problem, there is no substitute. Benchtop Shop Tools Occasionally at an event, a team will bring a drill press or other similar shop tool. If you’ve got the capability to bring one and are willing to allow other teams to use it as well, you’ll rarely be alone at an event. Drill presses, benchtop mills, and small lathes all allow for a fairly extreme amount of damage to be repaired at an event, often by frantically remaking the damaged part. Welder If you’ve welded a portion of your
machine together and you’re able to bring your welder, it’s worth the hassle. You’ll be quickly able to patch up damaged sections or repair broken welds, and it can often be the difference between doing the repair correctly or using duct tape.
There are plenty of other tools that you can bring with you, but outside of necessary specialized tools, these are the first ones you should look at bringing to an event. While it’s difficult to plan for every issue, these tools should have you prepared for the majority of situations you’ll run into when
competing. There will almost certainly be something that has been left off this list that will be useful to you. As a final step of the packing process, you should take the time to walk around your work area and take a look at each of your tools and think about if it could come in handy during the event. If you think you’ll need something and you’ve got the space and weight for it, bring it. Even if you don’t end up using it, there’s a good chance someone else will need one and your help could be the difference between someone making their next match or having to forfeit. SV
What to Expect at an Event verything’s packed, the robot is done (this part is VERY important), and it’s time to go to your first event. Now what?
E
bot down with the wheels off the ground and perform whatever normal maintenance you need to between fights.
to ask any last-minute questions you may have.
Arriving
Inspections
Typically, the venue will open several hours before the first match of the day to allow time for people to arrive, set up, and get through inspection. You should try to arrive as early into this period as you are able as this will allow you to be fully prepared for your first fight well in advance of the start of the event.
Run your bot through inspection as early as you are able to. If issues do come up, this will give you the maximum amount of time possible to resolve anything. If there aren’t issues, then you’ll have time to relax or take care of other pre-fight preparations without having to worry about getting anything else ready for your first match. Most inspections consist of a weight check, a visual inspection of the robot, and a failsafe check.
It’s time for your first fight. Many events will have at least the next few matches announced, so you’ll have a few minutes to prepare. If you’ve got a weapon lock or sharp edge covers, make sure they’re still secure, then take your robot, transmitter, and whatever tools/links/etc. are required for power-on to the staging area if the event has one. Once your fight is up, you’ll load in following standard event procedures. (If there is a bot wrangler, they will typically determine which robot loads first.) Once both bots are loaded and the doors are closed, you’ll be able to do a quick functional test to ensure everything is working as expected, then it’s time for the fight to start. Once the match is over, the bots will be loaded out also following standard procedures, and you can return to your pit for maintenance and/or repairs.
Your Pit Space Organizing your pit space is a great way to make sure you don’t waste time while making repairs or performing maintenance. If possible, have a dedicated location for batteries that are fully charged and a location for batteries that need to be charged. This will help ensure that there aren’t any mix-ups when replacing batteries between fights. Also, be sure to have a specific “work” area where you can set your
Driver’s Meeting The majority of events have a driver’s meeting shortly before starting the matches. Attendance is typically required at these meetings. Topics that are covered include things like the match format, key match procedures, event structure, and roll call to ensure that the brackets aren’t missing any robots. This is also a time
Your First Fight
Between Matches SERVO 02.2018
29
Combat Zone - Feb 18_Combat Zone - Aug 15.qxd 1/4/2018 9:09 AM Page 30
Early in events, there’s usually a lot of time between matches — especially if you’re running a single bot. That being said, the best habit to get into is to immediately take care of whatever repairs or maintenance you need to do following your match. Doing this means you’ll have more time to fix any issues you discover during maintenance, and you’ll have more time to charge the batteries you
were using for your last fight. Taking care of the between fight maintenance right away also means you’ll be far less likely to be called up for your next fight while you’re still trying to put things back together.
event. If you’re able to, try to stick around for it to either receive your trophy/prizes or support your fellow builders.
Closing Ceremonies
Packing up can start as early into the event as you’d like. When possible, if you’re pulling tools out to work on your robots, put them back in your tool box or keep them organized between uses. While that may add a bit of time to what you’re doing at the moment, in the long run it’ll save you time looking for a specific tool you were using earlier and/or when you’re trying to get packed up at the end of the event. Keeping only the essentials out and readily available during the event helps maintain a more open work area and reduces the chances of tools being obscured by other stuff on your pit table. Once your bot or bots are done fighting for the event, then you can pack away the rest of your pit area and head out or watch the rest of the event depending on how far into the bracket you’ve made it. I would recommend the latter. SV
Many events have some sort of awards presentation at the end of the
Packing Up
Make your machine move MICRO LINEAR SERVOS · 10mm-300mm stroke · 25kg+ available force · 6v-12v power supply · 15g-100g net weight ACTUONIX . COM
30
SERVO 02.2018
Anderson - Making of Andros - Feb 18_Blank Rough SV.qxd 1/3/2018 4:37 PM Page 31
The Making of Andros
By Mitch Anderson
I was at the point where making “toys” was not fulfilling anymore. I wanted to put my skills to work for something useful. I decided to design a police/military robot. I knew that they are very expensive, and I thought I could do a prototype that would be more affordable. I realized the complexity — especially of the arm assembly — so I was a bit hesitant.
O
ne evening while browsing eBay, I stumbled across a used “as-is” retired police robot. I thought it would be a great way to ease myself in this field by restoring a professional robot first and take those lessons into the next design. So, I made an offer of $10,000 on the Remotec Andros Mark 4. Quite a price, but not so bad considering that a new one is over $250k. The list price on eBay was $20k, but they took my offer. Remotec is the name in this field, and they don’t sell to the public.
The Process A week later, the machine came: 900 pounds including all accessories (such as a tether cable unit, for example). Some rubber tracks were broken, there was no documentation, and it seemed like it had not been fired up in a long time. I called the company; unfortunately, they didn’t support this model anymore with parts or documentation. I decided to re-do all the electrical stuff and remote control from scratch. I was facing 10 brushed DC motors, but I felt pretty confident that I could handle that.
Parts and Architecture For RC, I decided to go with a traditional 12-channel radio with a built-in video screen: the DEVO F12. I like things that are compact, and having the screen right there
Mitch and Emma Anderson, the father-daughter team working on the robot arm. Here, they’re installing the rifle module that can replace the grip unit.
was nice. On the receiver side, I used the matching DEVO RX1202. It’s stable and reliable, and much cheaper than the fancy RC names. For the signal processing, I decided to use the Teensy 3.5 development board since I heard they are incredibly fast (compared to my old time favorite, the Arduino Mega). I decided to use two processors: one for the traction wheels and the four “legs” (total of four motors); and one for the arm. The “Traction Teensy” was the receiver of all 12 PWM channels using IRQ functions. The traditional PulseIn is very slow for the processor. This Teensy would also communicate eight of those values to the “arm” Teensy through an I2C protocol. I don’t think that any Arduino model could deal with all this stuff in a timely manner, but the two Teensy boards did. I was really impressed. Next, I realized that I didn’t have enough proportional controls on the TX radio to deal with the wheel and arm SERVO 02.2018
31
Anderson - Making of Andros - Feb 18_Blank Rough SV.qxd 1/3/2018 4:37 PM Page 32
To post comments on this article and find any associated files and/or downloads, go to www.servomagazine.com/index.php/magazine/issue/2018/02.
The arm has been assembled back, but there were still issues to work on inside the main box. The robot opens like a box for access inside; the arm is resting on the table. This part of the body contains a 20 AH battery, four motors, a circuit breaker panel, DC motor control, and a few relays.
commands at the same time. I contemplated adding a second TX, but that was going to be cumbersome. Carrying two radios for one robot? I decided to make a “Mode” function in the software, connected to one of the RX binary switches. This way, the same proportional sticks would deal with either the wheels or the arm based on the Mode selection. I realized that I won’t ever drive and grab things with the claw at the same time.
Mechanical Issues With my daughter Emma’s help, we took apart all the hubs, cleaned them, and lubricated them. Andros runs on brass bearings (not wheel bearings), in order to deal with heavy loads. From existing pictures, I noticed the newer generations of this model have optional rubber wheels, so the unit (280 lbs) doesn’t wear out the tracks. This robot didn’t include that, but I wanted the option. Enter Home Depot’s wheelbarrow wheels at $25 a piece. That was the easy part. Attaching them to the hub was a challenge. As a spacer, we used a waterjet cut 2” thick piece of acetal on each wheel. We then made a connecting plate (1/4” aluminum) from the Andros’ hub to the wheel; each being screwed in to the hub by 20 10-24” Robot on its “toes” and the upper electronics box open. The two Teensy 2.5s, the RC receiver, the telemetry unit, and antennas reside here. An analog ammeter has been temporarily attached on the side to monitor power consumption (almost 30A when the robot climbs stairs).
32
SERVO 02.2018
Anderson - Making of Andros - Feb 18_Blank Rough SV.qxd 1/3/2018 4:37 PM Page 33
stainless screws. Andros is supposed to be rainproof, so all parts we used are either aluminum, brass, or stainless; this way, nothing can rust. It all worked out well. The wheels are solid. I can ride on the robot, and I’m 250 lbs.
Powering and Controlling the Arm We discovered the arm was more complex than the traction. Weighing 65 lbs on its own, we decided it would be better to detach it from the robot and install it on a separate table on wheels. The first step was identifying the wires coming out at the bottom; there were about 45 of them. Emma and I sat down patiently with the ohmmeter, finding pairs of 2-3 ohms of resistance between them (that is a motor). Next, we applied 12V on each pair from a battery and observed the motion. We documented everything such as “base rotation, right-left,” “shoulder rotation extend-withdraw,” etc. Luckily, there was no interruption in the wires, so everything powered fine. Next, I designed a circuit taking each pair to an H-bridge controller (nothing fancy; $16 on eBay), and I wrote the software on the Teensy that would take the RC signals and convert them to PWM and motor direction commands. After all The first part of the project: The arm was detached, so we took care of the was said and done, we connected all the traction and the four legs. We also built a ramp to drive the robot into the family’s Volvo SUV. Since the robot weighs 280 lbs, we had to test the ramp above-mentioned pairs to the H-bridges. It before attaching it to the car. It bent, but it held okay. The ramp solution all worked after a few hiccups, of course worked out well. (inverted wires, loose wires, minor stuff). So, there we were, on our knees with the remote picking up a 30 lb lead bar from the floor with the arm fully extended. That is impressive! Most arms are very limited in the weight they can hold. While playing with it, the shoulder motor quit working. Andros was designed with two cameras: one on the It was turning, but the arm was not lifting. We took it apart “hand unit,” and a fancier one (zoom, high-res) on the and discovered that the worm gear axle broke. We found “periscope” assembly in the back. They were both feeding the Engel motors distributor and he told me it would take the signal in a switch that would take the video output and eight weeks to get me one. There was no way we could send it as UHF to a receiver. wait that long, so I went to a machine shop in my I didn’t like the idea of switching the video, so decided neighborhood. to have two transmitters instead: one for each camcorder. I We took the motor apart, and they welded an even used the Boscam 2W RF model — the maximum power they thicker axle instead. We put the worm gear back in, and it make. I could then monitor both cameras (on two now works like a charm; even stronger than before. The monitors) or switch between them by toggling the power repair was $180, but well worth it. to each transmitter — front or back. The front was easy — a Finally, we put the arm back on the base of the robot, simple super wide FOV 600x400 cam. reconnected the wires, and it worked. For the back, I used an older Sony (HDR-SR10)
Cameras and Remote Video Receiving
SERVO 02.2018
33
Anderson - Making of Andros - Feb 18_Blank Rough SV.qxd 1/3/2018 4:37 PM Page 34
Disabling Demo from the Sony menus did not work. After power reset, it would go back to “Demo” after 10 min. What to do? I found the IR code for the “take a picture” camcorder function and I programmed the Teensy to tell the camcorder to take a photo every seven minutes, or 500,000 milliseconds. It worked! It’s kind of fun, actually. As we play with Andros, a sudden big flash happens at the most unexpected times.
What does Andros do?
In the foreground, you can see the arm of the robot. It’s been detached and installed on a rolling table. Weighing 80 lbs, it was most challenging to get the pinout correct. There are seven motors and connections to the upper camera. In the background, Emma is soldering terminals to a test connector.
camcorder with HD and some image stabilization (nice to have when the robot is in motion). This camcorder came with an IR remote that would allow zoom, record, etc. I wanted to have these functions available from my radio controller. I did some research on the ‘net and found the infrared commands for the zoom function for this model. I brought a couple of wires from one of the Teensy units to an IR LED that I parked in the camera box, right in front of the camcorder. I programmed one of the three-position switches on the radio TX to tell the Teensy to generate zoom in and zoom out IR commands to the LED. It worked. Now comes the unpredictable part: The darn camcorder would go into “demo mode” after 10 min of power-on. Not acceptable! The Andros might survey suspects for hours at the time.
Mitch got attacked. (Oh no! Are the robots taking over?) No project is complete until you have some fun.
34
SERVO 02.2018
Andros is mainly a bomb squad robot. The robotic hand can handle a package, open a door, go in a building, or drag a disabled person. Andros can also handle tools, cut a door down, drill holes, dig in the ground, sweep the earth with a mine detector, and punch holes in various materials. Andros also has a laser guided rifle unit. The rifle can be remotely aimed and fired. The robot has long-range remote video and audio capabilities, and can go into dangerous environments (hostage situation, toxic, radioactive, etc.) and video broadcast with sound.
What do I want to do with Andros? I would like to have a small “robot for hire” business. I studied electrical engineering in my native Romania, and I took computer science in the US when I arrived at the age of 23. My dad (and hero!) was a mechanical engineer, overseeing a machine shop of 60 workers. It was my favorite hang-out as a kid. He was also an inventor; in 1965, he redesigned suspension parts for Tatra trucks. When his design was adopted by the factory in Czechoslovakia, that earned him a promotion and a bonus. Later, he designed a rock drilling installation that would pump liquid cement inside the cracks of mountains. He worked for a hydroelectric dam company, and stabilizing tectonic movements was essential to the safety of the dam. I started my career at Xerox in the ‘90s as a field support engineer. Having a lot of idle time between service calls, I decided to fix and re-sell PCs. When I got laid off in ‘97, I turned that side job into a full-time business. By 2004, we were employing 16 people, but I was getting burned out. The business world is exciting, but is also a battlefield. I needed a change and wanted to explore other areas of life. I sold the business and devoted my time to my family — especially to my twins. When my son was 12, he told me how much he envied my childhood. I said “What? There was communism, shortages, no human rights ...” “Yes, but you’d go to your dad’s shop and make things. In the summer, you send me to those camps where boys only care about exchanging ringtones.” His words really got to me, so we started a garage workshop. I was eager to get my hands dirty again as well. We made lots of WW2 1/6 scale vehicles, and even won a couple of modeling prizes. My daughter, Emma soon jumped in.
Anderson - Making of Andros - Feb 18_Blank Rough SV.qxd 1/3/2018 4:37 PM Page 35
Action TV shows often feature robots. In a zoo, a similar robot was used to shoot a tranquilizer in a depressed feline that would not come out of the den. In mines, similar robots dismantle non-exploded charges, inspect abandoned shafts for safety, and monitor toxic gas levels. In chemical plants, robots can turn off valves in places where humans would not do well. Many of these businesses would not invest in the acquisition of such a robot and for the personnel training. Enter Andros.
potential clients, but their products can’t be disclosed right now. I’ve learned a lot from this restoration. The mechanical structure done by Remotec is very solid, and it would have taken me years to develop on my own. From what I know, I believe I’m the only private citizen to have a functional robot of this size and capability. SV
What will I do next? I would like to have a small fleet of three robots, with Andros being the biggest. Next, I’m working on the smallest one: “Polverson 1.” I’m building it from scratch and am designing an object recognitionretrieval capability, so it can roam a lawn (for instance), and identify and pickup a golf ball. I’m also discussing custom robotics projects with a couple of
SERVO 02.2018
35
Blankenship - Scribbler - Feb 18_Blank Rough SV.qxd 1/3/2018 4:38 PM Page 36
Avoiding Obstacles while Following a Line with the Scribbler 3
By John Blankenship
To post comments on this article and find any associated files and/or downloads, go to www.servomagazine.com/index. php/magazine/issue/2018/02.
Many people know that Parallax’s Scribbler 3 robot can draw pictures with precise movements because of its wheel encoders. However, the Scribbler’s IR and line sensors along with access to a hacker port provide capabilities that make it a contender for more mainstream robotic projects. That algorithm will be explained in detail, so you can make other robots perform these tasks even if you don’t own a Scribbler.
I
n the September 2017 issue of SERVO, Carol Lynn Hazlett demonstrated the Scribbler’s ability to make very precise movements. While such precision is impressive for drawing (letting the robot live up to its namesake), it’s generally not necessary for
autonomous sensor-driven behaviors. In fact, it’s easy to assume that a robot known for its ability to draw might not be worthy of conventional robotic projects. As you will see, such predispositions are unfounded. The truth is that the Scribbler 3 (S3) is an inexpensive fullyassembled robot with many capabilities that are worthy of your consideration. The purpose of this article is to spotlight those capabilities and demonstrate how easily they can be implemented using a version of the BlocklyProp language developed specifically for the Scribbler.
Available Sensors
Figure 1.
36
SERVO 02.2018
The Scribbler has many sensors, but those used in this article are two infrared units to detect objects in front of the robot and two reflective sensors for following a line. These alone are enough for some interesting projects, but the S3 BlocklyProp language has built-in support for servomotors and PING))) ultrasonic sensors connected to the hacker port (which provides six digital I/O lines and two A/D pins). For this article, a small servomotor will act as a
Blankenship - Scribbler - Feb 18_Blank Rough SV.qxd 1/3/2018 4:38 PM Page 37
rotating turret for the PING))) to provide ranging data.
Adding the Turret Figure 1 shows how easy it is to add a ranging turret to the S3. The main body of the servomotor was hot-glued to the back of a PING))) sensor, and a four-pin header was hot-glued to the servomotor’s output shaft. This allows the turret to be mounted by simply plugging it into the solderless breadboard also shown in the figure. The breadboard was attached to the S3 using double-sided tape. Note also that the servomotor and the PING))) are connected to the S3 hacker port (which also supplies both 5V and 3.3V to power external sensors). Figure 2 shows the turret mounted on the S3 in its operating position. I wanted a project that would demonstrate not only the PING))) turret, but also the line and IR sensors. Figure 3 shows what I came up with. The S3 will use its line sensors to follow the line shown, starting from the left side. While following the line, the S3’s IR sensors will be utilized to detect objects blocking the path. When an object is detected, the turret will be pointed forward and the PING))) data used to move the S3 until it is two inches from the obstacle. At that point, the S3 will reorient itself in preparation to follow the contour of the object until it finds the line again. It does this by turning the turret to the left and using the PING))) to maintain a fixed distance from the wall. The line sensors will be monitored during the line following, and when the line is detected, the S3 will reorient again, this time preparing to resume the line following behavior. The S3 will continue following the line until it finds a second obstacle before terminating the program. Everything could have been done with only the PING))) turret and the line sensors, but this approach also demonstrates how to use the IR sensors (which have the advantage of providing detection data faster than obtaining range information from the PING)))).
Figure 2.
Figure 3.
Figure 4.
The Program Figure 4 shows the main portion of the program used to implement this project. It starts by setting up three speed variables that will be used to control the robot’s movements throughout the program. The servomotor is then positioned directly forward. You would expect this to be 90°, but my servo and SERVO 02.2018
37
Blankenship - Scribbler - Feb 18_Blank Rough SV.qxd 1/3/2018 4:38 PM Page 38
Figure 5. Figure 7.
mounting required a parameter of 80 to be pointed directly forward. An IF statement in Figure 4 allows the main functions to be executed only if the reset button on the S3 is pressed. This allows the user to start the program by pressing this button. The four user-defined functions shown then make the robot perform the following tasks: Figure 6.
Figure 8.
38
SERVO 02.2018
• Follow the line until the path is blocked by an obstacle. • Prepare to circumnavigate the object by following its contour. • Hug the object’s contour until the line is seen again. • Prepare to follow the line by aligning with it. • Follow the line again until the path is blocked by an obstacle. Let’s look at each of these modules individually to see how they work. Figure 5 shows the FollowLineTillBlocked module. It begins by moving the turret to its forward position. Next, a loop continues as long as an obstacle is not detected by the IR sensors. Inside the loop, an IF statement gently turns the robot right or left depending on the state of the line sensors. You can control how fast the robot turns by experimenting with the speed parameters mentioned earlier. Figure 6 shows how the robot orients itself to prepare for the wall following behavior. The IR
Blankenship - Scribbler - Feb 18_Blank Rough SV.qxd 1/3/2018 4:39 PM Page 39
sensors can detect objects 8-10 inches away, so we need to move the robot closer to the object blocking the path before attempting to follow its contour. A loop does this by moving the robot forward as long as its distance from the object is greater than two inches. The robot then is rotated to the right 70° to align it with the wall. It will still be facing the wall a little, but that is preferred over facing away from the wall. Figure 7 shows the wall following routine. It starts by pointing the turret to the left (and slightly forward) to obtain the distance to the wall slightly in front of the robot (which enhances the wall following performance). A loop then turns the robot away from the wall when it gets too close, and toward the wall if it is too far away. This action continues until the line sensors detect a line. Figure 8 explains how the robot prepares to follow the line again. It starts by moving forward two inches to get itself over the line. Then, it rotates right until the line sensors indicate it is properly positioned. The last function call in Figure 4 simply calls the FollowLineTillBlocked module a second time to follow the line until an obstacle is detected before terminating the program. As you can see, BlocklyProp makes it easy to implement line following and obstacle avoidance behaviors on the S3. I’m hopeful that support will soon be added for the Parallax compass and background serial communication with user-definable pins. Such additions are already available on other Parallax products and would make even more advanced behaviors possible with the Scribbler 3. SV
FREE
Software
FRONT PANELS & ENCLOSURES YOU DESIGN IT WE MACHINE IT
NEW
DIGITAL PRINTING
1-800-373-9060 www.frontpanelexpress.com SERVO 02.2018
39
STEAM report - Feb 18_Blank Rough SV.qxd 1/3/2018 4:43 PM Page 40
The STEAM Maker Festival 2017 The STEAM Maker Festival is a collaborative venue for students, educators, and professionals within the community and industry to demonstrate programs, projects, practices, and resources that enrich STEAM education.
The STEAM Maker Festival provides an opportunity for community members to come out and display their commitment to the outreach of STEAM programs, and to show that Science and Technology can impact learning in fun and exciting ways. The San Diego STEAM Maker Festival unites sponsors, foundations, schools, parents, students, and community partners for a grand hands-on STEAM experience. 100% of all proceeds and sponsorships go directly to provide free events, programs, and activities to San Diego County schools, including all the STEAM Challenges which welcome hundreds of participants from 200+ schools, in addition to over 6,000+ attendees all from diverse socioeconomic backgrounds. With 42 school districts, over 200 participating schools, 100+ student teams participating in STEAM challenges, and industry/tech company demonstrations and activities, there is no other festival like it. The 2017 STEAM Maker Festival in San Diego, CA was held this past December 2nd at the Del Mar Fairgrounds. Here, we present reports from five 8th grade/14 year old students who give their impressions of the event.
40
SERVO 02.2018
STEAM report - Feb 18_Blank Rough SV.qxd 1/3/2018 4:43 PM Page 41
To post comments on this article, go to www.servomagazine.com/index.php/magazine/issue/2018/02.
Eric Davis
S
ince 2008, Droid Builder has been fascinating Star Wars fans everywhere with their clever Star Wars-like robots. Their R2-D2 is amazing, and it brings this character to life before your very eyes! This is a must see for any Star Wars and/or robotics fan. I was lucky enough to see Droid Builder’s R2-D2 at the STEAM Maker Festival in San Diego. I saw many great exhibits at the Festival that obviously took a lot of time and were outstanding. Lots of people and students were proud of what they had put together and I was really intrigued by them all, but my attention was especially drawn to the Droid Builder R2-D2 robotics project that focused on building Star Wars Universe droids. The Droid Builders biggest and most notable droid was the blue and white unit. The Droid Builders first started working on their droids in 2007 and the first finished R2-D2 was done in 2008. R2-D2 (or R2 for short) was a blue and white astromech droid. You might be asking yourself, “What is an astromech?” Well, an astromech droid — also called an astro droid or a mech — helped with power distribution on the ships and with co-piloting. R2 was from the planet Naboo. Creating the droids really seems like an involved and elaborate process. The creativity of the R2-D2 specifically is amazing and took a lot of pieces to construct. The droid builders had to go section by section when creating and putting it together. The sections included making the dome, body, legs, ankles, feet, and accessories. It’s worth mentioning each section in detail. First, let’s talk about the dome. Aluminum parts such as the dome ring, dome bumps, holo projectors with lenses, and many other items were necessary just to make the dome. The next section was the body which required many pieces as well; for example, aluminum skin mounting blocks, skin straps, and more. Then, there were the shoulders which included shoulder shims, shoulder hubs, and much more. From there, they had to make the legs, ankles, feet, and accessories. The process seemed very detailed (honestly, I didn’t follow it completely when the droid builder was explaining it to me). I did get the sense that the builder was very passionate and knowledgeable, and it took a lot of time and patience. Another aspect of the building process included prepping and painting the parts. The builders had to ready the aluminum and steel by sanding and filing it, and finally
taping off everything so it could be painted. Each part took 4-6 coats of paint, which included primer and then layers of the various colors. (I think they must have consulted the actual Star Wars movie set team for the colors because they were so exactly like the droids in the movie.) The next step was assembling the droid. Some parts had to be glued together while others had to be cut and drilled, and then fastened together with nuts and bolts. The electrical portion seemed more complicated, but basically
SERVO 02.2018
41
STEAM report - Feb 18_Blank Rough SV.qxd 1/3/2018 4:43 PM Page 42
STEAM
included a seven-channel radio control system, a dual controller, forward and reverse speed control, switches, resettable fuses, wires, batteries, and volume control. Building a droid seems like something not just anybody could do. The Droid Builders’ booth was extremely cool and drew a lot of attention. They had one realistic sized R2 roaming around their booth, plus they also had 3-4 smaller droids moving around the zone as well. Lots of kids and their parents were excited, walking around, having their photos taken with the droids and just generally having fun. It was
amazing to see something from such a mega hit blockbuster come to life. People loved it! The noises the droids made were exactly like what we heard in the movie theaters, and the way the lights flashed and lit up was equally authentic. It was definitely one of the busiest booths at the Festival. Another great thing about the presentation was that Droid Builders had their own people walking around answering questions and talking about the droids. These people could be easily identified because they were dressed up like other characters from the Star Wars period. This was extremely cool and added to the feeling of being on a movie set. These “characters” were very knowledgeable about all things droid and Star Wars. Having Droid Builders available to talk to people who visited their booth really added to the presentation because people were able to learn more about the main characters themselves and all about the actual build of the droids. The whole experience really made me appreciate the art of presentation. If you aren’t able to present your project well and interact with an “audience,” it won’t be noticed much, and certainly won’t be the center of attention.
Lucie Kaskoun and Annika Huff
T
he 2017 STEAM Maker Festival was super cool this year. It included many different exhibits that ranged from student-run booths to booths run by professional organizations. We were able to interview a young man by the name of Lorenzo van Munoz. We’ll describe what van Munoz has accomplished, what organization he is from, some of the struggles he has dealt with, and lastly what has brought him to STEAM Maker Festival 2017. One of the exhibits was done by the San Diego Youth Space Program (or SDYSP). Their mission is to provide high school students with the ability to send actual experiments into space. Their
42
SERVO 02.2018
STEAM report - Feb 18_Blank Rough SV.qxd 1/3/2018 4:43 PM Page 43
Science, Technology, Engineering, Art & Mathematics purpose goes farther than this, though. They find that by teaching teens and young adults these important concepts, they are helping them work towards the future. They have been successfully doing this for a while. The SDYSP has created things like carbon dioxide monitors and phototropism in microgravity modules. These are incredibly important experiments, as they help us learn about outer space, which is a place we still don’t know much about. Instructor van Munoz has been working hard on a project called the nanorack box. The nanorack box is an experiment that tests the difference in amino acids from earth and space. This box can prove useful for many reasons. It suggests altered molecular behaviors of lysine — a major component of DNA strands — in space have a role in the strange gene expression patterns noted on the space station. This is extremely important to know because it tells us how being in space affects our human bodies. Some items van Munoz’s team created for this experiment included making a system to utilize multiple chromatography strips, constructing a mechanical system out of memory shape wire to manipulate the slides into the vehicle of the camera, and developing a chemical detector which allowed them to observe transparent amino acids with flourosine. Even though the team faced many difficulties while accomplishing these tasks, they were able to persevere and overcome. However, they were faced with a more difficult obstacle: figuring out how to fit everything into a small rectangular box about the size of a cardboard toilet paper roll. They also had to decide what the best and most optimal setup was; for example, what the best position of the cameras would be and the largest amount of chromatography strips in the view of the camera. Mr. van Munoz and his team had previously been at the STEAM Maker Festival in 2016. For this year, they had created a phototropism experiment. Phototropism is the orientation of a plant or other organism either towards light or a source of light, or away from a light or source of light. This experiment was created to show how plants grow in outer space and whether or not plants display phototropism in microgravity. The experiment included a computer system that tracked the ability a plant has to grow in microgravity. It was launched aboard
the SpaceX Falcon 9 rocket and got to call the International Space Station home for 30 days. This experiment was extremely important to do because it helps to show how humans could live in space one day. This experiment showed that plants could grow in microgravity, and plants are necessary for human survival in space as they provide food and oxygen. One of the other activities at the Festival was the $250 social change challenge. Students were asked to create real change in the environment, cities, and neighborhoods, and the way people around the country think. If their proposal was chosen, they were eligible to receive funding up to $250. We believe this is crucial because by the younger generation learning about how to help out the community, they are learning skills they will need throughout their life. If you just try and persevere, you can do it. The sky is the limit at STEAM Maker.
SERVO 02.2018
43
STEAM report - Feb 18_Blank Rough SV.qxd 1/3/2018 4:43 PM Page 44
STEAM Luke Rohen
T
he 2017 San Diego STEAM Maker Festival was great. All the booths were very interesting and creative. The one exhibit that I liked the most was on remote control vehicles.
44
SERVO 02.2018
A group of high schoolers engineered a robot/vehicle that had to be able to shoot wiffle balls into a basket, and whoever made the most won. I selected this booth as my favorite because of all the effort the students put into it — from designing the robot platform, to building the controls and electronic sections. The size of the hole they had to shoot the balls into was one foot wide. The height of the basket was about eight feet. One of the team members said it took them about three months in total to fully complete their build. The steps to making this robot were not easy. First, you had to assemble a team, then make a proposal. After that, you would start the build which required a ton of materials which, in turn, required a lot of money. The team that I talked to said they spent almost $1,000. They also said that the hardest part was figuring out the hardware. (I tried building a simple robot before and it was not easy.) The final product this team constructed turned out to be 3 x 3 feet. All of the robots had some way to pick up the balls and shoot them up at a 75 degree angle into the hoop. The team I interviewed made 10 out of 20, so they came in second place and were very happy. There were 10 teams in total. The robot this one team designed scooped up the balls, put them into the bed of the robot, then shot them out one by one by pressing a button on the controller. The design had padding around the edges and had a compartment for the balls. Also, the robot was able to scoop up all 20 of the balls. I believe this group exhibited all the qualities of STEAM. Every part of the build and competition included science and technology. The robot required lots of engineering and math skills to make and complete. Even art came into it when the teams were decorating their robots with different colors and designs.
STEAM report - Feb 18_Blank Rough SV.qxd 1/3/2018 4:43 PM Page 45
Science, Technology, Engineering, Art & Mathematics Sam Benedict
T
he STEAM Maker Festival hosts many schools, makers, and companies that exhibit different things such as medieval fighting, bridges, and telescopes. The Festival also had booths from Drama Kids International, General Atomics, and Microsoft, among other companies. One of the many booths at the Fair was the History Battle Zone provided by the Adrian Empire. They showed off full metal armor, traditional medieval garb, and an arsenal of medieval weapons. They hosted a booth where they had kids shoot arrows with a soft tip at knights in full armor. It looked so cool, that I had to try it too. They also had two knights in full armor fight with each other. It was awesome to watch. It was bordered by a booth from the Adrian Empire. They also sold various medieval looking items. These booths were fun to check out and they added a really cool vibe to the Festival. St. Vincent de Paul school showed off marble rollercoasters built on paper tracks. They also displayed cardboard helmets with lights on the side. Each helmet had a different design. Good Shepard Catholic School showed off several different things; one item in particular was a Galileo telescope. They explained in great detail how the telescope worked. Since this was their first year at the Festival, they also shared the challenges they experienced in preparing their booth. Other schools presented things like molecule representations and even a garden. The STEAM Maker Festival does an awesome job of getting students into science. The Microsoft booth showed off different things such as their new Xbox One S and their new computers with drawing screens on them. They also set up some computers that people could test out. General Atomics made liquid nitrogen ice cream. It was really tasty and a lot of fun to watch. Drama Kids International had set up a booth with
props where kids could participate in play-like activities to give an example of the classes they present to students. Even Fantasy Donkeys was there. They dress up donkeys and bring them to special events. It’s kind of like hiring a party clown, but with donkeys. The Festival is a great platform for companies to share their field of science in a way that interests kids and adults alike. It gives an environment for fun learning that kids can take home with them and be inspired by. This helps kids find what really interests them which helps them with their future career choice. SV SERVO 02.2018
45
Secura - Beginner Guide to CNC routers - Feb18_Blank Rough SV.qxd 1/3/2018 4:44 PM Page 46
Beginner’s Guide to CNC Routers
By Roger D. Secura
After moving into a larger house and basement, I finally decided to design and build a desktop CNC router. I spent a lot of time researching CNC routers online. As everyone knows, working online late at night can suck the life out of a human faster than a vampire. Nevertheless, I survived and finally finished building my desktop CNC router. If you’ve been mulling over the idea of building a CNC router, I should warn you the learning curve is quite steep. This article is my attempt to flatten out a very small part of that learning curve by describing the basic hardware and software requirements for building a CNC router. Later in this article, I will try to demystify some of the concepts, terms, and operating procedures associated with CNC routers. Although I’ll be referring to the Mach 3 CNC program throughout this article, the concepts and procedures presented here are general enough to be applicable to some of the more popular CNC programs.
What is a CNC Machine? A quote from www.thomasnet.com states, “CNC machining is a process used in the manufacturing sector that involves the use of computers to control machine tools. Tools that can be controlled in this manner include lathes, mills, routers, and grinders. The CNC in CNC Machining stands for Computer Numerical Control.” Other machine tools that fall under the CNC category are plasma/laser/water cutters, 3D printers, welders, pick and place machines, etc.
In the Beginning, There Were Hand and Power Tools What makes a CNC router so different from other tools? First, it can perform many of the same jobs that hand and power tools do — routing, drilling, sawing,
46
SERVO 02.2018
planing, boring, tapping, engraving, etc. Secondly, CNC routers are well known for their accuracy and repeatability. The accuracy of a CNC router can fall within a few ‘thousandths’ of an inch. The repeatability factor allows you to make 100 pieces of the same part and have each one come out an exact copy of the first one. Imagine how tiring, tedious, and timeconsuming that would be using simple hand and/or power tools.
Where Do I Begin? On the software side, you’ll need three programs: CAD (Computer Aided Design), CAM (Computer Aided Manufacturing), and CNC. Refer to Figure 1a. The process of designing a part for your CNC router begins with a CAD program. Whether it’s a few wooden gears needed to build a mechanical wall clock, robot, or an anemometer, a CAD program can help you create just about any size gear pattern. Once the gear drawing is finished, you “Export” or save the 2D drawing as a “.dxf” file (ASCII text file, NOT a binary file). Other file extensions can be used, but .dxf has become more of a standard file format for exchanging 2D drawing files between CAD and CAM software. The next step is to open the CAM program and import the .dxf file. The CAM software will take the file (gear pattern) and create what is known in the CNC machining industry as a “toolpath.” A toolpath is just a series of X, Y, and Z movements the router’s cutting tool must follow to make a part. The next operation for the CAM software to perform is to generate a “G-code” program file based on the toolpath of the gear pattern. A G-code program is a list of the X, Y, and Z toolpath coordinates the CNC software (Mach 3) uses
Secura - Beginner Guide to CNC routers - Feb18_Blank Rough SV.qxd 1/3/2018 4:44 PM Page 47
To post comments on this article and find any associated files and/or downloads, go to www.servomagazine.com/index.php/magazine/issue/2018/02.
to cut out a part. G-code programs are saved as an “.nc” or “.tap” file, and can be opened and edited in Notepad. Unfortunately, not all CNC machines (routers) can use the generic Gcode instructions put out by the CAM software. So, before any final G-code files are created, you need a “post-processor” program to optimize (configure) and then generate a G-code program specific for your CNC machine. Most CAM software packages include a post-processor. The last piece of software you’ll need to acquire and learn is a CNC program. The CNC software (Mach 3, for example) takes the G-code program (.nc or .tap file) from the CAM software and converts the code into motor control instructions. These instructions are transferred to a “controller board” via a USB or ETHERNET cable (see Figure 1b). The controller board, in turn, sends individual instructions to each one of the three motor “driver” circuits. The driver circuits control the motion of the X, Y, and Z stepper motors mounted on the CNC router (see Figure 1c). So, on the hardware side, you’ll need a laptop or Tip #1: It’s important desktop computer (Windows that you stick to one PC); a controller board with unit of measurement motor driver circuity on board (mm or inches) or three individual driver throughout the whole boards; three stepper motors; CAD/CAM/CNC and one 12 or 24 volt power supply for the controller board process. and motors. If you’re planning on using a laptop to control your CNC router, a USB or Ethernet compatible controller board will be required. In the next section of this article, I will try to clear up DISCLAIMER: The author and publisher of this article are not to be held libel for any physical injuries or property damage stemming from the information in this article. CNC machines, like all power tools, can be extremely dangerous — especially in the hands of someone who is inexperience with the setup and operation of a CNC router. It’s the responsibility of the CNC machine operator to know his/her machine and practice all safety procedures.
Figure 1.
Tip #2: Laptop computer users should turn off all automatic updates, antivirus programs, screensavers, power management settings, and any other “background” programs which can cause an interruption of the router during its operation. If possible, use that old Win 7 laptop you have sitting in the closet as the dedicated CNC computer. some of the confusing terminology surrounding CNC routers and, if possible, save you from the Internet vampire. It’s going to get a little bumpy, so put on your seatbelt.
Down the Rabbit Hole Okay, you’ve got an idea of what parts are required to build a CNC router. Now, let’s move on to some of the more challenging stuff. This includes some of the terms you’ll need to know like: “Part Zero,” “Program Zero,” “Work Offset,” “Machine Zero,” “Hardware Limit Switches,” “Software Limit Switches,” and “Homing Switches.” As you will learn, all these things work together in the setup and safe operation of your CNC router.
Take a Look What I’d like you to do now is look at Figure 2 for a minute to get yourself acquainted with the layout of a typical homebuilt CNC router. What you are looking at in Figure 2 is a top (aerial) view of the router. In other words, you’re looking down at the CNC router table from the Z axis.
Part Zero and Program Zero Normally, when designing a part (a wooden gear, for SERVO 02.2018
47
Secura - Beginner Guide to CNC routers - Feb18_Blank Rough SV.qxd 1/4/2018 8:42 AM Page 48
example) in a CAD program, the designer will designate a point on the drawing where the X, Y, and Z coordinates are set to 0, 0, and 0. This reference point is commonly referred to as Part Zero. In other words, all features on the part drawing are referenced (i.e., measured) from a single point: Part Zero (X = 0, Y = 0, Z = 0). The Part Zero location is not only important to the CAD drawing as the part’s origin, but it’s a key piece of information for both the CAM and CNC software. The CAM software needs the Part Zero reference point to generate a toolpath program (G-code) for the gear pattern. The CAM software gives you the option of using the Part Zero coordinates to create a toolpath program, or you can specify a new origin point. Either way, once the toolpath program is generated, the origin of the part is generally referred to as Program Zero. The CNC software (Mach 3), on the other hand, needs the Program Zero coordinates to position the gear pattern onto the workpiece. In other words, the Program Zero point can be positioned at the center or one of the four corners of the workpiece. Regardless of where Program Zero is stationed, its main function is to “tell” the CNC software where on the workpiece (wood, for example) the cutting process should start.
piece of wood. Normally, the lower left-hand corner of the workpiece is designated the Work Offset location (refer again to Figure 2). In turn, the CNC software will use this Work Offset location (corner) as the part’s Program Zero origin point (X = 0, Y = 0, Z = 0). This is the location where it will execute the gear program (G-code) and begin the process of cutting out the gear pattern. There’s just one problem. Since you have the option of placing the workpiece anywhere on the router table, how will the CNC program (Mach 3) “know” what location you chose? The answer is rather simple. All CNC machines have a Machine Zero point (a.k.a., “Home” position) on the table from which all other X, Y, and Z coordinates are referenced — including Work Offsets. Unlike huge and expensive industrial CNC milling machines that have a permanent Machine Zero location constructed into the machine, homebuilt CNC routers and kits usually have a user defined Machine Zero point somewhere on the router table. Look at Figure 2 one more time and you’ll notice the Work Offset location (X = 4.00”, Y = 3.00”, Z = -0.75”) is referenced (measured) from the Machine Zero coordinates. Now, don’t confuse Machine Zero with Part/Program Zero. Machine Zero (Home) is a permanent reference point on the router table. Part Zero, on the other hand, is the part origin as specified on the gear drawing by the CAD designer. Program Zero is the toolpath origin as designated by the CAM software or a G-code programmer. Look at Figure 3 to see how the CAD and CAM zero origins line up with the lower left-hand corner of the workpiece. Also notice in Figure 3 how the Work Offset (X, Y) — which is measured from Machine Zero — determines where on the router table the lower left-hand corner of the workpiece is positioned.
Work Offset and Machine Zero
Setting Up Your “Home”
To position your workpiece (wood) at a specific location on the router table, you have to set up something called a Work Offset. A Work Offset can be any random location on the router table where you’ve clamped down a sacrificial
Since every X, Y, and Z position on a CNC router table is reference from Machine Zero, it’s always a good idea to set up a Machine Zero location on your table before doing anything else.
Figure 2.
48
SERVO 02.2018
Secura - Beginner Guide to CNC routers - Feb18_Blank Rough SV.qxd 1/3/2018 4:44 PM Page 49
All you need to do is pick a point on the router table where you want Machine Zero to be located. As mentioned, this point is stationed in the lower left-hand corner of your table some distance away from your workpiece. It’s perfectly acceptable to choose a different location on the router table, but it will be more confusing to the beginner at this point in the learning curve. Next, using the keyboard arrow and page up/page down keys, slowly “jog” the X and Y axes so the center of your cutting tool is directly over the location you’ve chosen for Machine Figure 3. Zero. Now, jog the Z axis upwards to a point you’d like to call Machine Zero for the Z axis. Once the center of the cutting tool and the X, Y, and Z axes have reached their Machine Zero destinations, watch the main screen in Mach 3 and you’ll see some numbers on the Digital Read-Out (DRO) display. Verify that the Machine Coordinates button is turned on (lit red). At this point, you “zero-out” (clear) the X, Y, and Z coordinates by hitting the “Ref All Home” button on the DRO display so it reads 0, 0, and 0. In turn, Mach 3 will recognize and remember the X, Y, and Z locations you’ve chosen on the router table as Machine Zero. Now, when you run the gear pattern program (G-code) and it calls out a “G28” command (go to the Home position), all three axes will automatically move to your new Machine Zero coordinates (X = 0, Y = 0, Z = 0). You can also enter the G-code command G28 into the Manual Data Input (MDI) screen in Mach 3 and it will automatically send all three axes to the Machine Zero position on your table.
program where the first Work Offset (i.e., “G54”) is located on the table in reference to Machine Zero. Now when the G-code program (gear pattern) is run, Mach 3 will look up the first Work Offset location (G54) and — starting at Machine Zero — move the cutting tool to the first Work Offset coordinates (Program Zero location). This is where Mach 3 will run the G-code program and begin cutting out the gear pattern. Remember, as long as your CAD software specifies Part Zero on the drawing and your CAM software or G-code
I’m a Little “Offset” You can set up a Work Offset in Mach 3 by clamping down a piece of wood at a random location on your CNC router table. Then, using the Machine Zero position as a starting point, jog the center of the cutting tool to the lower left-hand corner of the workpiece. Starting at the top of the Z axis (Machine Zero), SLOWLY move the Z axis downward so that the center of the cutting tool barely touches the top surface (corner) of the workpiece. Again, looking at the DRO display on the main screen in your software, mark down on a piece of paper the X, Y, and Z coordinates for future reference. At this point, you zero-out (clear) the X, Y, and Z coordinate buttons (not the Ref All Home button) next to each DRO so it reads X = 0, Y = 0, Z = 0. This tells the CNC
Figure 4. SERVO 02.2018
49
Secura - Beginner Guide to CNC routers - Feb18_Blank Rough SV.qxd 1/3/2018 4:44 PM Page 50
programmer designates a Program Zero origin, you can place the workpiece (wood, for example) anywhere on the CNC router table just by setting up a Work Offset in your CNC software. In Mach 3 and most CNC programs, the first six Work Offsets are G54-G59. That means you can set up six pieces of wood anywhere on the table and Mach 3 will know where each one is located. For example, let’s say you wanted to make six different sized wooden gears. First, you’d clamp down six different sized pieces of wood at six random locations on the router table (see Figure 4). For Mach 3 to find each piece of wood on the table, you would set up six Work Offset locations. First, starting from Machine Zero, you would manually jog (keyboard) the X, Y, and Z axes to the lower left-hand corner of the first piece of wood. Next, you would clear (zero out) the X, Y, and Z DRO display Figure 4a. by hitting the X, Y, and Z buttons. This sets up the first Work Offset G54. Finally, you would return all three axes to the Machine Zero point on the table, click the next Work Offset button (G55, on the Offsets screen in Mach 3), and then repeat the above process for the other Work Offsets (G56-G59). After you’re done, the six Work Offset settings might look like the following — depending on the size of your table. We’re assuming in this example that the workpiece size varies (length/width), but the thickness of each piece of wood is the same (also see Figure 4a): G54: G55: G56: G57: G58: G59:
X X X X X X
= = = = = =
4 4 4 10 10 10
Y Y Y Y Y Y
= = = = = =
3 Z = -0.75 6 Z = -0.75 10 Z = -0.75 3 Z = -0.75 6 Z = -0.75 10 Z = -0.75
To test that all six Work Offsets are functioning correctly, go to the main screen in Mach 3. Now, assuming your CNC machine is starting at Machine Zero (X = 0, Y = 0, Z = 0), the router table is clear of any workpiece or clamps, and you have selected the G54 Work Offset button in the Offsets screen, hit the ‘Go to Zero’ button. [Author’s note: The label on this button is misleading. It should be labeled Go to W.O. (Work Offset).
50
SERVO 02.2018
Users will incorrectly think they are going to Machine Zero when the button is really sending you to a Work Offset location.] This will send your X, Y, and Z axes to the G54 Work Offset coordinates (X = 4.00”, Y = 3.00”, Z = -0.75”). Now, select the next Work Offset (G55) and hit the Go to Zero button. This time, your router will move from the G54 coordinates to the G55 coordinates. You can return to the Home position (Machine Zero) at any time by returning to the MDI screen and entering the G28 command into the text box and hitting the enter key. Remember, the Work Offset coordinates shown in Figure 4a are the X, Y, and Z locations of the lower lefthand corner of each piece of wood. Also, don’t forget that Work Offsets are always referenced (measured) from Machine Zero (Home position). So, when you move the Z axis (i.e., cutting tool) downward towards the top surface of the workpiece, it should start its descent from the Machine Zero position (top of the Z axis: Z = 0). The DRO in Mach 3 should display negative numbers as you lower the Z axis towards the lower left-hand corner of the workpiece. The Z = -0.75” in Figure 4a is the distance the bottom edge of the cutting tool would have to travel downwards to reach the top surface (corner) of the workpiece. WARNING! Failure to allow for workpiece thickness or the length of the cutting tool could damage your router or worse: cause you physical injury. If you change the thickness of the workpiece(s), and/or change the cutting tool, you MUST redo the Work Offset setup procedure for the Z axis. That means you send the Z axis back to its Machine Zero location at the top of the Z axis. Slowly move (jog) the bottom edge of the cutting tool downward towards the top surface (corner) of the new workpiece. Make a note of the negative Z value displayed on the DRO. Finally, you zero-out (i.e., clear: Z = 0) the Z axis on the main screen in Mach 3. Now, if you go to the Work Offset screen, you’ll see the new negative Z value for Work Offset G54. Just make sure to copy the new G54 Work Offset number (Z = -0.75”, for example) to Work Offsets G55, G56, G57, G58, and G59 — assuming all boards are the same thickness.
Secura - Beginner Guide to CNC routers - Feb18_Blank Rough SV.qxd 1/3/2018 4:44 PM Page 51
Limit Switches One of main reasons you need limit switches is to protect your machine from physical damage. Whether it’s you or a G-code program moving the X, Y, and Z axes across a CNC table, crashing into the machine’s framework is easily done unless you set up some travel boundaries. There are three types of switches you can set up on a CNC router: hardware limit switches; software limit switches; and homing switches.
Hardware Limit Switches As mentioned, the purpose of hardware limit switches is to stop the X, Y, and Z axes from accidently crashing into the router’s framework. Hardware limit switches used on CNC routers are just simple single-pole-double-throw (SPDT) normally open (N.O.) / normally closed (N.C.) snap action switches (see Figure 5). The minimum number for a CNC router is six switches. Normally, you would put all six switches in series and configure each one as normally closed. Two switches go on the Y axis, a short distanced from the opposite edges of the table (refer back to Figure 2). Two more switches are mounted at both ends of the X axis. The last two switches are attached to the top and bottom of the Z axis framework. Once installed, the limit switches can stop the router from moving anytime any one of the X, Y, or Z axes travels beyond a set boundary. In other words, the hardware limit switches set those boundaries.
Software Limit Switches As a second “wall-of-defense” to the hardware limit switches, we employ a different set of switches: software limit switches. They do exactly what hardware limit switches do, except they are set up inside a CNC program (Mach 3). Notice back in Figure 2 that the Soft Limit line (dotted line boundary) is positioned in front of all the SPDT hardware limit switches. If any one of the three axes crosses a Soft Limit boundary line, it will trip a “switch” in Mach 3, forcing it to stop the router in its tracks. This setup helps to protect your router from damage should you or a G-code program accidently move any one of the three axes too close to the hardware limit switches. In other words, soft limit switches act like a buffer to the hardware versions. The soft switches also “tell” Mach 3
Figure 5. what you think should be the safe limits of your router table (typically within an inch or so from the edges of the table). You can set up the Software Limits in Mach 3 by entering the minimum and maximum travel limits for each one of the X, Y, Z axes. Mach 3 will treat the ‘min’ and ‘max’ Software Limits for each axis as just another set of SPDT N.O. hardware limit switches. It’s important to remember that Software Limits are always referenced (i.e., measured) from Machine Zero (Home position). That means the min and max numbers can have a positive or negative value depending on where the Software Limits are in relationship to the Machine Zero position.
Tip #3: Always verify that the Soft Limits button in Mach 3 is turned on (lit green) before you start any cutting operation. Put this on your “Pre-Flight” checklist. This will help protect you and your CNC router.
Homing Switches Finally, we come to Homing Switches. These too are SPDT mechanical switches. They are mounted onto the router’s frame not to set a boundary for any X, Y, and Z axis movement, but to consistently and accurately find one particular location on the table: Machine Zero (i.e., Home position). Some CNC operators prefer a more consistent and accurate way of finding Machine Zero. They set up their homing switches on the CNC router by picking a spot SERVO 02.2018
51
Secura - Beginner Guide to CNC routers - Feb18_Blank Rough SV.qxd 1/3/2018 5:47 PM Page 52
for a cutting tool. Just twist the toothpick into one end of a new pencil eraser as shown in Figure 6 and Figure 7. This will allow you to “play” with your X, Y, and Z axes and see if you really know what you are doing without damaging your machine or injuring yourself. The sharp end of the toothpick will also help to pinpoint all the important locations on your table (Machine Zero, Work Offsets, etc.). • Run a CAM Simulator program that employs animation to show you how the gear will be routed on your CNC router. This will give you a chance to see on a computer screen if the gear program (G-code) has any routing problems. Some CAM programs have this feature. Mach 3 also has a rudimentary toolpath simulation feature. • Run your gear program (G-code) in Mach 3 without anything inserted into the collet (chuck). In other words, turn off your spindle motor and let your router do a dry run (i.e., “cut air”). As the gear program runs, watch the collet and see if it looks like it’s following the gear pattern as it moves through the air above your workpiece (wood).
Stop It! Figure 6.
Figure 7.
somewhere on the router table and designating it Machine Zero (Figure 2). Next, they jog all three of the router’s axes to the chosen location. This is where they mount three SPDT switches (X, Y, and Z) onto the router’s framework. It should be noted here that homing switches are not a mandatory requirement in order to operate a CNC router. However, since all X, Y, and Z coordinates are referenced from Machine Zero, it might be important to you to have a more permanent Machine Zero location on your table.
Danger, Will Robinson! I feel obligated to warn all the beginners out there who plan to build or purchase a CNC router. It is imperative that you DO NOT insert any cutting tool (bit) into your new CNC router UNTIL you are completely satisfied you understand how to set up and operate your machine. Your inexperience with CNC routers can damage your machine and/or cause you physical harm. Here are three steps I suggest you follow for your own safety: • To be safe, take a toothpick and use it as a substitute
52
SERVO 02.2018
All CNC machines (mills, routers, lathes, etc.) come equipped with a big red emergency stop button (E-Stop). So should yours! Remember, if this is your first experience with CNC routers, ALWAYS keep a finger on the E-Stop button when your CNC router is in operation, just in case something unexpected happens.
Tip #4: SET STEPS PER UNIT! It’s extremely important that you calibrate your router so that when Mach 3 “says” it moved the X axis one inch on the DRO display, it has actually physically moved the X axis one inch on the router table. All you need is a ruler (1/32”) to calibrate your machine. One axis at a time, you position (jog) the X, Y, and Z axes to the edge of the ruler. If you go to the Settings tab in Mach 3, you’ll find the ‘Set Steps per Unit’ button. Just follow the prompts and Mach 3 will guide you through the process.
The Finish Line I barely scratched the surface of what you need to know about CNC routers. I hope you learned something in this article that you can use with your new CNC router. Stay safe! SV
Harres - Ultrasound Refresher - Feb 18_Blank Rough SV.qxd 1/3/2018 9:48 PM Page 53
Ultrasonic Radar Refresher
By Dan Harres To post comments on this article and find any associated files and/or downloads, go to www.servomagazine.com/index. php/magazine/issue/2018/02.
Robots commonly performing obstacle detection rely on active sensing. That is, they project energy of some type — whether light, RF, or acoustic — in the direction of the possible target and measure the reflected energy returned to a receiver. SERVO 02.2018
53
Harres - Ultrasound Refresher - Feb 18_Blank Rough SV.qxd 1/3/2018 10:21 PM Page 54
Ultrasonic Radar several GHz. Let’s break that down a little more. Acoustic propagation refers to the transmission of sound through changes in the pressure levels as the energy travels through some type of medium such as air or water (we’ll concentrate on air). It travels through the air at the speed of sound, which is on the order of 343 meters per second at standard temperature and pressure (20°C at sea level). To illustrate what is meant by frequency, we can use the example of a piano. You know that the keys at the extreme left of an acoustic piano are referred to as the “low notes.” Their very deep bass tone is the result of the metal strings that the associated hammers strike, causing them to oscillate at “low frequencies.” This means the string vibrates from peak to peak a very small number of times per second. The lowest of a concert piano’s notes are vibrations that oscillate only about 30 times per second; these are referred to as 30 Hz. At the extreme right side of the piano keyboard are the “high notes.” These notes have strings that — Figure 1. Swinging requires the use of resonance. when struck with the associated hammer inside the piano — vibrate at frequencies as high as 4,000 times per et’s discuss ultrasonic methods for object second (4,000 Hz). detection by going over some People with normal hearing can detect the entire fundamentals. We’ll start by talking range of piano notes, and some folks can even detect frequencies as high as 20,000 Hz. about the general situation of detecting objects. Beyond this frequency of 20,000 Hz, humans do not hear the sound (many animals, however, have hearing to Humans (and some machines) use vision and to a frequencies far beyond this limit). Because the sound lesser extent hearing to avoid collisions or otherwise cannot be heard by humans, it’s possible to propagate detect objects in their path. In that case, the system is considerable energy at these frequencies without annoying using passive light energy or passive acoustic energy to people or otherwise interfering with their normal activities. detect objects. Most machines performing obstacle detection rely on active sensing. That is, they project energy of some type — whether light, RF, or acoustic — in the direction of the possible target and measure the reflected energy returned to a receiver. So, how do we create ultrasonic waves? Typically, this When the energy is in the RF region of the is done with a transducer, which takes electrical energy electromagnetic spectrum, this type of system is called modulated at the appropriate frequency and converts this RADAR (RAdio Detection And Ranging). The term radar is to mechanical energy that moves a surface, creating the acoustic propagation. also sometimes used when the energy is in the light part of the electromagnetic spectrum; in this case, it’s A common type of hobbyist ultrasonic transmitter is a sometimes called LIDAR (LIght Detection And Ranging) or piezoelectric ceramic transducer, typically operating at 40 kHz. Such a piezoelectric device has the unusual property LADAR (LAser Detection And Ranging). that it expands or contracts as the voltage across it When the energy is in the ultrasonic region of the increases or decreases. acoustic spectrum, the term “ultrasonic radar” is used. Therefore, by driving it with an AC voltage, the That’s what we’ll be talking about here. device’s surface in a particular axis moves with respect to the opposite surface. Such a device can be made to change its dimensions at 40 kHz and above. In addition, the device can be Ultrasound is acoustic energy propagated at manufactured so that it is “resonant” at a specific frequencies above human hearing; generally 20 kHz to frequency.
L
Creating Ultrasonic Energy
Just What is Ultrasonic Energy? 54
SERVO 02.2018
Harres - Ultrasound Refresher - Feb 18_Blank Rough SV.qxd 1/3/2018 10:21 PM Page 55
How Does Resonance Work In order to understand piezoelectric ultrasonic devices, we need to understand resonance. Lasers, microwave ovens, that squeal your car makes burning out causing the neighbors to stare — these are all examples of resonance. One example that we’re all familiar with is a child swinging (Figure 1). A child merely pushing with their feet from a starting position causes the swing to move only slightly. To make the swing move great distances requires the child “to swing.” What this really means is that the child must learn to move the lower legs forward or backward in synchrony with the swing’s movement. When the swing reaches its backward-moving limit, the child rapidly rotates the lower legs forward and, likewise, at the forward-moving limit, the lower legs are quickly moved back. In this way, additional energy is imparted to the swing with each iteration, resulting in a large steady-state “amplitude.” Before we leave this resonance example, let’s think about one more aspect of the situation that is typical of all such resonant systems. The system (in this case, the child and the swing) has a natural frequency at which it operates. The swing and the child, in fact, constitute a pendulum. The natural frequency of this system depends only on the length of the swing chains. In the case of a piezoelectric device, the device’s natural frequency is determined by its dimensions and the device material. Consider the situation when a voltage is generated across the device. The wall of the device moves, creating a wavefront that moves through the device, striking the opposite wall of the device, then heading back to the originating wall. This roundtrip time of travel constitutes the period of the natural frequency. If we vary the voltage across the device at this natural frequency, we create a resonant behavior within the device, much like the child on the swing. After several periods of such voltage change, the amplitude of the wall movement (and therefore the transmitted sound) becomes relatively large.
mechanical transformation can be used to do the opposite. When piezoelectric devices are subjected to external force, the device generates a voltage which can be amplified and detected. In fact, some applications use a single transducer in a half-duplex mode to transmit a sequence of pulses and then “listen” for the return of those pulses (such a circuit will be discussed later in this series). Most applications use separate transducers for transmit and receive. Although the force to which the piezoelectric transducer receiving the acoustic wave is small and the associated output voltage is low amplitude, an amplifier with sufficient gain raises the amplitude to a useable level.
Ultrasonic Ranging Simple radar applications use Time-of-Flight (TOF) to determine distance to an object. This is a fairly straightforward calculation. In the case of ultrasonics, the wavefront travels to the object, then back to the ultrasonic receiver, at the speed of sound. So the distance is simply given by: D=
c(TOF) 2
where D is the distance and c is the speed of sound (343 meters per second). Unfortunately, the calculation is muddied a bit by the fact that it may not be exactly clear how to make the TOF measurement. Figure 2 shows typical transmit and receive waveforms for an ultrasonic transducer. We reasonably choose the start of the transmit signal as the beginning of the time-of-flight, but where should we choose to say
Sensing Ultrasonic Energy Okay, so a piezoelectric transducer can convert electrical energy into mechanical energy and thereby allow us to create ultrasonic pulses. But how can we sense ultrasonic energy? It turns out that the same type of piezoelectric transducer that was used for electrical-to-
Figure 2. Transmit and receive signals.
SERVO 02.2018
55
Harres - Ultrasound Refresher - Feb 18_Blank Rough SV.qxd 1/3/2018 10:22 PM Page 56
clutter, a return signal that falls off rapidly with distance, and transmitter ringdown.
Clutter
Figure 3. Directivity graph for a typical ultrasonic transmitter.
time-of-flight ends? Perhaps we should use the start of the reflected waveform. Or, the peak.
Issues with Ultrasonic Detection We’ve already mentioned the ambiguity in determining TOF, but this is a relatively minor issue, since it generally results in an uncertainty of less than an inch which — for many hobbyist robot applications — is tolerable. Other issues, however, are more serious. These include
Clutter is a potential problem in any radar application, but particularly a problem with ultrasonic applications because of the wide field of view (FOV) of the ultrasonic devices. Figure 3 shows a directivity graph that is similar to the charts for most ultrasonic transmitters. The figure shows that the transmitter still has about 1/10 its power at ±30° from boresight. Such a large FOV means that the device can “see” not only pertinent objects in front of it but also irrelevant objects far from the robot. In fact, the ultrasonic response shown back in Figure 2 is an example of this. In that particular application, the transmitter/receiver was mounted about four feet above the floor. It was pointed directly at a target about five feet away (the second of the two largest responses). A fluorescent light fixture hanging from the ceiling a couple of feet above the transmitter/receiver was actually causing the first large response. The transmitter/receiver responded to this light fixture because it was within its field of view. Such “false alarms” reduce the reliability of the ultrasonic sensor’s results and often lead to the conclusion that ultrasonic sensors make poor ranging devices.
Ringdown
Another problem plaguing ultrasonic transmitters is the fact that they cannot immediately stop their movement when the voltage stops changing. This is related to their resonant nature. Just as a child swinging cannot immediately stop but must instead let the swing slowly lose energy, the piezo transmitter must likewise slowly stop its movement. Figure 4 shows an ultrasonic transducer subjected to a 0 to 30V square wave and then — mid-screen — switched to a high-impedance connection. The transmitter continues to oscillate, generating voltage as it slowly “winds down.” The reason this is important is that ultrasonic receivers often have a difficult time distinguishing between the signal produced by ringdown and an actual return from a very close object. As a result, most ultrasonic receivers establish a “dead time” during which the receiver does not attempt to identify targets. Thus, most ultrasonic sensor systems cannot identify objects that are very close. Figure 4. Transmitter subjected to 16 periods of square wave showing ringdown.
56
SERVO 02.2018
Harres - Ultrasound Refresher - Feb 18_Blank Rough SV.qxd 1/3/2018 10:22 PM Page 57
Ultrasonic Radar Significant Signal Attenuation with Distance
Thus, if the return from the target at a two foot distance is S, at twice that distance (four feet) the signal will be down to S/16. It’s easy to see that a return signal that is a relatively large amplitude one or two feet away may require a huge gain increase or other non-trivial processing method to be reliably recognized at, say, 10 feet.
A signal sent through the air will diminish as a function of distance. So, just how fast will the ultrasonic signal diminish? Figure 5. Ultrasonic transmission and We’ll ignore acoustic absorption signal return. of air since this is a relatively minor effect at distances of a few feet, and instead just concentrate on signal attenuation as the result of wavefront expansion. With all of these problems, it’s not surprising that Figure 5 depicts what is happening. We know that hobbyists sometimes find using ultrasonic devices the wavefront expands in both dimensions normal to the frustrating. Fortunately, these issues can be solved with transmission axis. So, the signal is proportional to (1/r2), where r is the distance from the transducer. some basic understanding about how they function, Once the wavefront hits the target, it’s dispersed by making them a popular choice for obstacle detection and the target and similarly expands, also resulting in a avoidance in robotic applications. SV decrease in signal as a function of r2. So, the signal experiences a 1/r4 overall reduction.
Final Thoughts
SERVO 02.2018
57
Carroll - Then & Now - Feb 18_Then & Now - Sep15.qxd 1/3/2018 2:38 PM Page 58
Robots in Our Lives by Tom Carroll
TWCarroll@aol.com
The Seattle Robotics Society had an interesting discussion recently at one of our meetings on the roles of robots in our lives, led by Steve Kaehler. As he mentioned, they can be companions, assistants, protectors, pets, and entertainers, as well as be used in numerous other applications. Though I write about all varieties of robots, it is the personal robot that most of us are most interested in — myself included. in factories and various or those of us who industries, employed in don’t yet own a robot different tasks that we for our house, it certainly is rarely get to see being at the top of our wish list; performed. either as one that we build Robotics is said to be from scratch or buy from a the next technological retailer. However (and a big revolution, and many however at that!), are the writers tout the future of home robots on today’s robotics in glowing terms market truly what we’ve (myself included). Placing always envisioned as a all the other robot personal companion robot? applications such as Gene DeMaitre, Editor of military, industrial, and Robotics Business Review other non-personal made an interesting Figure 1. The Jetson's Rosie the Robot maid from the 1962 TV series. applications aside, just comment two years ago in what is the future for the his article, entitled: When extrapolated 100 years into the future personal robot? Will Robots Become as Common as Those of us who are interested in as the robots of 1962 had barely Smartphones? He stated: “Current the various applications of robots have made an entry into the factory home robots are still playing catch-up invariably seen many more types of environment, and were decades away to Rosie the Robot” (Figure 1). robots at exhibitions, universities, and from becoming commonplace in the DeMaitre was referring to a “Robots robotics groups. The personal space home. Come Home” session at the 2016 Even today, we have been that we call home is very different Consumer Electronics Show. surrounded by robots for decades, but than any other robot operating arena most of these have been tucked away and requires a very special type of
F
The Future of the Home Robot Figure 2. iRobot Roomba history. When cartoonists envisioned the future back in the ‘60s, they clearly saw robots as part of the family. In the 1962 TV cartoon series, The Jetsons, Rosie showed just how great of a robot companion she could be in the year 2062. The writers of that TV series wisely
58
SERVO 02.2018
Carroll - Then & Now - Feb 18_Then & Now - Sep15.qxd 1/3/2018 2:38 PM Page 59
To post comments on this article and find any associated files and/or downloads, go to www.servomagazine.com/index.php/magazine/issue/2018/02.
robot to maneuver in an everchanging environment.
The Annual Consumer Electronics Show No matter how many types of robots make their public debut at the International Consumer Electronics Show (CES) in Las Vegas every January, it is the robot designed for the home that draws the biggest crowds. Unfortunately, a lot of the journalists at CES and similar exhibitions have some vague ideas about electronics for entertainment but do not have a clue about robotics and the different robots on display. You can tell by how they talk about them: “cute,” “cuddly,” “adorable,” etc. Fortunately, other types of robots available on the marketplace have found a place in our homes.
iRobot Leads the Way for Robots to Enter Today’s Home Outside of toys, the one robot that has made the greatest penetration into private homes is the vacuum cleaner robot, with the popular iRobot Roomba at the top of the list with $15 million in sales. Figure 2 shows a chart of the history of iRobot’s products, with the Roomba vacuum cleaner a huge chunk of their sales income. iRobot’s management began their product designs with toys, and also considered industrial floor cleaning machines, but it was their Roomba series that hit it off with the public. Yes, it was the early adopters who bought the first robot vacuum cleaners, but their interest spread to millions of other eventual users. The first robot vacuum cleaners were as good as any other of the growing competition, but people commented they cleaned floors in a manner similar to sheep grazing in a
Figure 3. Neato BotVac D7 Connected.
pasture (a strictly random pattern), and sometimes missed areas of carpet completely. A newer robot vacuum cleaner company, Neato Robotics came on the scene in 2010 with what was later to be called the Neato BotVac. Their latest BotVac D7 Connected is shown in Figure 3. It uses a new type of navigation called SLAM (Simultaneous Localization And Mapping) that employs a rotating laser LIDAR to map a room that is shown on a smartphone in the figure. They now have a series of 15 different cleaners. Many robot hobbyists and experimenters have used the same LIDAR module shown in Figure 4, sold separately by suppliers or hacked from a Neato vacuum for navigation in mobile robots. I believe this new but affordable LIDAR technology has led the way for more capable mobile robots in the home environment. MEMS micromotion sensors, ‘time-offlight’ laser distance sensors, and some incredible image recognition cameras have joined inexpensive LIDAR units to allow robot experimenters to design and build some amazing robots for the home. More on that later.
g{xÇ tÇw aÉã ago, Bill Gates wrote an intriguing article in Scientific American entitled: A Robot in Every Home. Gates is really not a robotics engineer, but his extensive business and technical background keeps him abreast of all categories of technology and computers. He looked to talented and knowledgeable people to keep him informed when writing the article. Gates had earlier tapped one of his senior executives at Microsoft, Tandy Trower, to form a robotics group in the company in 2005. In June 2006, Trower and his team brought forth a robotics development package called Microsoft Robotics Studio, and later in 2008, the Microsoft Robotics Developer Studio. In the beginning of his article, he outlined the rapid growth of microprocessor-based computers and the initial struggle people had to figure out what this new technology was good for. He made this statement about robotics: “What I really have in mind is something much more contemporary: the emergence of the robotics industry, which is developing in much the same way that the computer business did 30 years ago.” He also looked at people’s view of robots, or what they felt robots should be and made a correct observation. “... we have a long way to go before real robots catch up with their science-fiction counterparts. One reason for this gap is that it has been
A Robot in Every Home Just about 10 years
Figure 4. Neato LIDAR laser rangefinder.
SERVO 02.2018
59
Carroll - Then & Now - Feb 18_Then & Now - Sep15.qxd 1/3/2018 2:38 PM Page 60
in the much larger group of consumer and home personal robots. This type of robot has been fairly straightforward to design and market due to their relative simplicity to construct. iRobot, Neato, and other robot vacuum cleaner manufacturers did not have to add complex arms, speech recognition systems, and associated software to produce a desirable product for the home consumer. iRobot did branch out and produce a series of successful ground robots for the military, as well as pool and gutter cleaning robots for the homeowner as shown in Figure 2.
much harder than expected to enable computers and robots to sense their surrounding environment and to react quickly and accurately.” Today’s home robots seem to be popular more for their simplicity of use than functionality.
Personal Robots I believe Gates was a bit off in his evaluation of the robotics industry: “ ... which is developing in much the same way that the computer business did 30 years ago.” As much as we might wish that was true, the mechanical, power sources, and sensor aspects of robotics has held its development back and has frustrated many robot developers. Safety aspects are one issue. One does not have to fear that their computer will fall down the stairs and hurt somebody, or their keyboard keys will pinch someone. A mobile machine that interacts with a human can be dangerous if poorly designed and/or constructed, or used incorrectly. Most personal robots have a
What Qualities and Appearance Should a Personal Robot Have? Figure 5. Early Icelandic settler robot in Reykjavik Museum.
single purpose since this seems to be the best way in which to enter the robot manufacturing business. Vacuum cleaner robots fall into the category of ‘single-purpose’ — robots
Figure 6. Where's WALL-E among these 200 movie and TV robot characters?
60
SERVO 02.2018
Looking at this very basic design issue, should personal robots look and sound like us? In 2062, Rosie the Robot rolled around on what looked like a single three-wheeled roller skate and had silly antennas sticking out the sides of her head that made her look more like a 1942 robot. Looking back at Figure 1, Rosie did have two arms and for one reason or another, ‘she’ had a third arm that popped out of a little trap door in her chest to sweep up trash from a floor. (These days, a Roomba would pop out.) How do homeowners feel about the actual look of a potential personal robot for the home? Do they have to look human, even a little bit? People are many times taken aback and startled when they see a robotic creation that looks very much like a human. The term ‘Uncanny Valley’ describes an almost creepy feel that robots can give us by their sheer looks. My wife and I visited a museum in Reykjavik, Iceland
Carroll - Then & Now - Feb 18_Then & Now - Sep15.qxd 1/3/2018 2:39 PM Page 61
g{xÇ tÇw aÉã motors and control several years ago where systems. The new cobots they were depicting the (collaborative robots) are early settlement of the closer aligned to a home country. There was a robot with the ability to figure of a man (shown work alongside a human, in Figure 5) who was so and compliance in their realistic that it startled arms makes for a safer my wife, Sue. “He’s real, robot. A cobot such as Tom! His chest is moving Baxter made by Rethink in and out as he Robotics (and shown in breathes. He’s an actor Figure 8) is a safe robot standing there.” It was design. Rod Brooks, one moving, but he was just of the original coa very well-made robot in founders of iRobot left to the world-class Perlan Figure 7. Bruce Dern with Silent Running drones Dewey (1) and Huey (2) co-found a new company Museum built into part of after Louie was lost. with Ann Whittaker. They a huge hot-water tank human shapes and characteristics. had this new idea about affordable that was no longer used. Artist Richard Sargent took a bit Some of the most recent ‘home’ industrial robots that didn’t need to of artistic license with the whimsical robots have taken non-humanoid be separated from humans with a collage in Figure 6 using the popular shapes. cage or fence. ‘Where’s Waldo?’ series for the search of Disney character WALL-E: a garbage-collecting robot stranded on a future polluted Earth where the remaining humans had escaped to an orbiting space station. WALL-E is The average person (even those I’ve mentioned some quirky inserted within about 200 robotic with an extreme interest in robot points about robots, touched on some characters from films and television building) might assume that a typical unique ideas that people have about a shows. industrial robot is more advanced and robot in the home, and compared You will enjoy looking at all the has many more capabilities than a some features of industrial and mobile simple robot for the home. Yes, they home robots. We all are experiencing vastly different robots in the scene. are more expensive, but the costs are robots in our lives in several different Just imagine how many other forms for extreme rigidity, accuracy in ways, but what type of robot can and shapes will be sketched by repetitive motion, reliability over many serve us best in our homes? The prospective robot developers in the hours of operation, and expensive reason that single-purpose home search for the ultimate personal home robot designs rule in the robot. (Sargent’s collage is available as a poster market place is that more size on the Internet if complex robots are vastly you’d like to get one for more difficult to develop. yourself.) Robots in Hold out your hand earlier science fiction and look at its movies were almost complexity. I’m not just always human-sized talking about the variations until the 1971 opposable thumb and film, Silent Running four fingers. Consider all presented Huey, Dewey, the many axes of motion and Louie (Figure 7): the that allow you to move cute little service drones your hand, and how for the doomed space powerful the grip is. ship, Valley Forge. Think about how simple Later, Star Wars’ R2it is to flip a quarter back D2 became an immediate and forth over the top of hit. Soon, most robots your fingers or twiddle a began to take on nonball-point pen while Figure 8. Rethink Robotics' Baxter collaborative robot.
Comparing Industrial Robots with Personal Home Robots
The Home Robot of Today and Into the Future
SERVO 02.2018
61
Carroll - Then & Now - Feb 18_Then & Now - Sep15.qxd 1/3/2018 2:39 PM Page 62
example, look to Jibo as an entertaining social robot.
Mobile Home Robots
Figure 9. Artist's Impression of robots fighting for combat robot book cover.
you’re thinking about something. Hold a thread and place it into the tiny eye of a needle. Now, add your two arms and extend each of your very unique hands in wide arcs of motion. Our body’s arms and hands are far stronger and far more dexterous than the most amazing humanoid robot in existence. Yes, some one-ton industrial robots can handle several hundredpound payloads, but not even a humanoid the size of Baxter can traverse a home with the strength and dexterity of a human.
Where is Complexity Needed in a Home Robot? Looking again at the simple cartoon of Rosie, we can see that she has a single axis of motion at the shoulder and the same at the elbow, and a simple claw for a hand on each of the two arms. Is that all we really need for a home robot to manipulate objects around a house? I apologize for picking on old Rosie, but I just wanted to make a point. Her depiction is what a typical non-technical person would imagine a robot to be. People want to be entertained and don’t care about the
62
SERVO 02.2018
Looking at mobile home robots (ones that actually move around the floor), most of the newer and existing home robots can rove around and Figure 10. Kuri home robot by Mayfield Robotics. look very cute like the Kuri robot shown complexities that go into a real robot. in Figure 10. Made by Mayfield Robotics in Redwood City, CA (a When Pete Miles and I wrote Bosch company), this charming little Build Your Own Combat Robot back guy is quite capable technically, but in 2002, I complained that the cover still just a small robot with a nodding picture with a whirling saw blade on and turning head. the end of a pencil-thick rod would be Kuri doesn’t have any sort of impossible. My request was ignored functional arms, and uses ‘hands’ or because it was the combat action of claws. He seems to be quite a bit like the saw and giant pickaxe with the the Echo and Jibo in that their main sparks flying (as seen in Figure 9) that was wanted — not realism. That way features are they verbally and audibly of thinking still exists in so many ways communicate with humans. about how technical products are Nonetheless, it still is a great little designed. robot for $700.
Desired Capabilities of a Home Robot
More Features for Today’s Home Robots
Back in Figure 5, you saw almost 200 different movie robots and none were that close to another in appearance. Everyone’s idea of a robot is certainly different from anybody else’s preferred external appearances and internal functional design. That certainly holds true for the home robots on the market today. Consider Cynthia Breazeal’s Jibo that is now on the market after three long years of waiting. Pronounced jee-bo, this robot is touted as an intelligent personal assistant; Jibo has a movable body to reflect motions as ‘he’ talks, though it does not actually move across a surface. If you already have an Amazon Echo digital assistant, for
As I suggested earlier, robots will need more than cuteness and advanced social and verbal communication skills to function as a true home service and companion robot; a robot may also need manipulative skills to assist a person. Take a look at the Paro robot baby harp seal shown in Figure 11. It has been around for over a decade and costs almost $6,000, but it’s specially designed to be a companion for patients with dementia. It has voice recognition and sensors to feel petting and rubbing. With just a few flipper, head, and body movements, its main purpose is to soothe a person, not act as an active toy. At $6K, you are not going to find
Carroll - Then & Now - Feb 18_Then & Now - Sep15.qxd 1/3/2018 2:39 PM Page 63
g{xÇ tÇw aÉã Paro at Toys R Us. People have argued that robots like Paro provide an illusion of a relationship, and those who find human relationships challenging may turn to robots for companionship instead.
Communications with a Personal Home Robot Kuri, Google Home, Jibo, Amazon’s Alexa assistant, and even fluffy Paro all have microphones and some have speech recognition, and other home robots even have facial recognition to say “hello” to their owner upon arriving home. In what other manner can we humans communicate with others, or even with robot companions? How about with gestures that are the most innate language of all mammals.
Useful Robot Arms and Hand/Claws/ Pincers/Grippers
Figure 11A. Paro, the baby harp seal therapeutic robot with a patient.
Figure 11B. Paro, the baby harp seal therapeutic robot.
at Amazon for $130 a pair) might be the answer. The right and left set would make a great addition to a personal robot; all you need is a set of 4-DOF
(degrees of freedom) arms to maneuver the hands into the right positions to perform useful tasks. Remember my description of our human hand versus a typical robot’s hand? Do we need the small finger manipulations that humans can attain, or will a simpler and much less expensive manipulator arm suffice? As you can imagine, typical model-aircraft types of servos only have a limited amount of torque, and when longer arm segments and fingers are moved by the small servos (even with the largest ones that an experimenter can find), you will not equal the strength of an equivalent human arm/hand. To equate a human’s capabilities, robot developers designing a personal assistant robot for the marketplace will either just live with the weaker appendages on their robot or come up with far more capable motors systems.
Robot Vision
A capable personal assistant Toy robots (and even Rosie) only robot designed to serve our physical need light bulbs or red LEDs for eyes, needs (such as retrieving needed but we know that these will never items) will need a bit more than serve as real vision for robots. simple verbal and visual My early builds used CdS recognition skills. Not only will (Cadmium Sulfide) photothe robot need to recognize resistive cells that basically were certain objects, it will require one pixel each. They could the physical means to grasp and detect the presence or absence move the object to another of light only. Even line follower location. This means a gripper robots might have a row of on the end of an arm of phototransistor sensors to sufficient strength, length, and determine the black pathway manipulative capability. that the robot must follow. A simple two-part gripper When we get into pattern may suffice, but more than recognition that I mentioned likely a three to five fingered earlier — especially facial gripper will be the better recognition — we need multioption. The servo-driven hands thousand pixel cameras and Figure 12. Dual five-finger robot hands are available at many shown in Figure 12 (available intelligent processing. sites on the Internet. SERVO 02.2018
63
Carroll - Then & Now - Feb 18_Then & Now - Sep15.qxd 1/3/2018 2:42 PM Page 64
Figure 13. Intel Euclid with RealSense Depth camera.
The Carnegie Mellon CMU Cam was and still is a good robot camera, and there are many nice digital cameras on the market for less than $20 that can interface with a Parallax Propeller, Arduino, Raspberry Pi, or whatever microcontroller you use. One very nice robot camera system on the market is the Intel Euclid Developer’s Kit shown in Figure 13. The Euclid features the RealSense camera coupled with an Intel Atom quad-core CPU with pre-installed Ubuntu and ROS operating systems. This is a very capable $289 camera/processing system; you can read all the details online that are too numerous for me to list. Go to the Intel site for more information. Another very unique and powerful robot vision system that I described a few months ago is the nVidia Jetson Development Kit available for under $200 (Figure 14). You can read more about how MIT grad students created some very capable mobile robots on the nVidia site or my previous article. As I mentioned in my article, nVidia has long been known for top-of-the-line graphics processors that are the key to many video game consoles, as well as
64
SERVO 02.2018
supercomputer processing. The Jetson TK-1 is a very affordable processing board for advanced mobile robot hobbyists as well as robotics researchers.
Final Thoughts
that surpass today’s lithium-ion batteries are on the horizon. I do believe that it’s the mechanisms that need to be greatly improved to allow a home robot the capability to manipulate objects and even physically assist persons for whatever reasons. The HuiHui shown in Figure 15 is an assistive robot from China that was first introduced in 2010. It’s a great start at a home robot, but the complexity of the arm and hand mechanisms dictates some complex machining in the production of the
I began this article, not to necessarily instruct readers on how to build a capable personal assistant home robot, but to enlighten folks on what progress has been made to bring us closer to a truly functional robot to assist us (and the elderly) in our homes. We now have sensors (for example, the many very inexpensive MEMS sensors) that have become available to robot builders. The Intel Euclid and nVidia intelligent cameras and vision processing boards have made robot vision infinitely more capable than a pair of red light bulbs or CdS photo sensors. Batteries Figure 15. Chinese HuiHui robot with complex arm with sufficient power density mechanisms.
LED Lighting for Everything
)
For the finest in robots, parts, and services, go to www.servomagazine. com and click on Robo-Links.
Figure 14. nVidia Jetson Development kit.
COMPONENT C OMPONENT LEDs LED BULBS ACCENT LED A CCENT LIGHTS
Carroll - Then & Now - Feb 18_Then & Now - Sep15.qxd 1/3/2018 4:48 PM Page 65
g{xÇ tÇw aÉã robot. The humanoid robot’s ‘innards’ shown in Figure 16 is the iCub, another very mechanically complex robot. Both robots come close to being useful within a home as an assistant robot, but are far too expensive for the average homeowner. I’ve studied assistive robots for decades, and the robotics community will ultimately succeed in producing a very capable personal home robot. Hopefully, one of you readers will be on that team of roboticists. SV
Figure 16. iCub robot innards.
Actuonix Motion Devices .......................30 All Electronics Corp. ................................13 ExpressPCB ...............................................35 Front Panel Express ..................................39 Hitec ............................................................2 IR Robot Co. .............................................39 M.E. Labs ..................................................30
In the January 2018 issue of SERVO, the incorrect Advertiser Index was run in the print magazine. It was the December 2017 version, instead of the new one for January. Here is a corrected index for January 2018. We apologize for any inconvenience. Actuonix Motion Devices ......................10 All Electronics Corp. ........................32, 65 ExpressPCB .............................................45 Hitec ...........................................................2 PanaVise ..................................................41 Pololu ........................................Back Cover SDP/SI .....................................................32 ServoCity ...........................................65, 67 Tormach .....................................................7 PanaVise ....................................................12 Pololu .........................................Back Cover Super Bright LEDs ....................................64 Tormach ....................................................11
Advertiser Index
SERVO 02.2018
65
SV Webstore - Feb 18_SV Webstore May 16 working.qxd 1/3/2018 2:46 PM Page 66
The SERVO Webstore CD-ROM SPECIALS
02.2018 FEATURED
ROBOTICS Arduino Robot Bonanza by Gordon McComb Create high-tech walking, talking, and thinking robots. "McComb hasn’t missed a beat. It’s an absolute winner!" Breathe life into the robots of your dreams — without advanced electronics or programming skills. Arduino Robot Bonanza shows you how to build autonomous robots using ordinary tools and common parts. Learn how to wire things up, program your robot's brain, and add your own unique flair. $29.95
Robot Builder's Sourcebook Fascinated by the world of robotics but don’t know how to tap into the incredible amount of information available on the subject? Want the names, addresses, phone numbers, and web sites of companies that can supply the exact part, plan, kit, building material, programming language, operating system & computer system? Robot Buider’s Sourcebook is just what you’ve been looking for! $36.00
66
SERVO 02.2018
Making Things Move: DIY Mechanisms for Inventors, Hobbyists, and Artists by Dustyn Roberts
In Making Things Move: DIY Mechanisms for Inventors, Hobbyists, and Artists, you'll learn how to successfully build moving mechanisms through non-technical explanations, examples, and do-it-yourself projects — from kinetic art installations to creative toys to energy-harvesting devices. Photographs, illustrations, screenshots, and images of 3D models are included for each project. $29.95
Build Your Own Humanoid Robots by Karl Williams GREAT 'DROIDS, INDEED! This unique guide to sophisticated robotics projects brings humanoid robot construction home to the hobbyist. Written by a well-known figure in the robotics community, Build Your Own Humanoid Robots provides step-by-step directions for six exciting projects, each costing less than $300. Together, they form the essential ingredients for making your own humanoid robot. $24.95
Robots and Robotics: Principles, Systems, and Industrial Applications by Rex Miller and Mark Miller Written by a pair of technology experts and accomplished educators, this comprehensive resource provides a solid foundation in applied industrial robotics and robot technology. You will get straightforward explanations of the latest components, techniques, and capabilities along with practical examples and detailed illustrations. $90.00
Robotics Demystified by Edwin Wise YOU DON'T NEED ARTIFICIAL INTELLIGENCE TO LEARN ROBOTICS! Now anyone with an interest in robotics can gain a deeper understanding — without formal training, unlimited time, or a genius IQ. In Robotics Demystified, expert robot builder and author Edwin Wise provides an effective and totally painless way to learn about the technologies used to build robots! $19.95
To Order Call 800 783-4624 or visit our webstore
SV Webstore - Feb 18_SV Webstore May 16 working.qxd 1/3/2018 2:47 PM Page 67
Order online www.servomagazine.com SPECIAL OFFERS
Build Your Own Quadcopter by Donald Norris Build and customize radio-controlled quadcopters that take off, land, hover, and soar. Build Your Own Quadcopter features step-by-step assembly plans and experiments that will have you launching fully functioning quadcopters in no time. This fun, do-it-yourself guide fuels your creativity with ideas for radical enhancements, including return-to-home functionality, formation flying, and even artificial intelligence! $50.00
The SERVO Buddy Kit
PROJECTS 3D LED Cube Kit
PS2 Servomotor Controller Kit
From the article “Build the 3D LED Matrix Cube� as seen in the August 2011 issue of Nuts & Volts Magazine. An inexpensive circuit you can build to control a servo without a microcontroller.
For more information, please check out the May 2008 issue or go to the SERVO webstore.
Includes an article reprint.
$39.55
This kit shows you how to build a really cool 3D cube with a 4 x 4 x 4 monochromatic LED matrix which has a total of 64 LEDs. The preprogrammed microcontroller that includes 29 patterns that will automatically play with a runtime of approximately 6-1/2 minutes. Colors available: Green, Red, Yellow & Blue. Jig and plastic cases also available.
This kit accompanied with your own PlayStation controller will allow you to control up to six servomotors. Includes all components and instruction manual. For more information, please see the February 2011 edition of SERVO Magazine. Assembled units available! $79.95
$57.95
SERVO 02.2018
67
Romi
Balboa
Programmable balancing robot kit that can stand itself up and drive around on two wheels
...and more
Everything from mechanical parts and jumper wires to motor drivers and voltage regulators
Versatile robot platform with integrated battery compartment, motors, and wheels; several add-on board options available
Zumo
Complete integrated Mini Sumo robot on a tracked chassis, featuring a variety of sensors
Finding the right parts for your robot can be difficult, but you also don’t want to spend all your time reinventing the wheel (or motor controller). That’s where we come in: Pololu has the unique products—from A-Stars to Zumos—that can help you take your robot from idea to reality.
Find out more at www.pololu.com Full Page.indd 68
1/3/2018 4:51:40 PM