AdditiveManufacturing
Andrew Flynn
PDE 3
AdditiveManufacturing Additive Description
Fused Deposition Modelling
Additive Processes
• Dispenses two materials, one to make the object, and one to make a support structure. Builds from bottom up, one layer at a time, using CAD model.
Electron Beam Melting
• Materials: Thermoplastics
• Uses an electron beam in a vacuum to melt metal powder, layer by layer. Parts created are dense, free of voids, and very strong. • Materials: Metals
Additive Manufacturing: Definition
Design a product that will benefit from the use of additive manufacturing. Show how the user will interact with the product service and where the role of the designer lies within the product design cycle.
“process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies.”
User Design Additive manufacturing provides the user with an easy means of creating bespoke custom products. In this example a simple digital interface has been used to create custom jewellery.
Home Printing It is becoming more common to have access to 3D printers within the home. This could redefine the way products are sold with the user simply printing what they want on demand, from home.
Medical Use By taking a 3D scan of the body, surgeons can print life like bone structures using additive manufacturing to help aid them in surgery.
Stereolithography
• Highly focused UV laser traces out successive cross-sections of a 3D object in a vat of liquid. • Materials: Thermoplastics (photopolymers)
Selective laser sintering
Andrew Flynn
The Brief: In Short
PDE3
Component Reduction Using certain additive manufacturing processes, components that once comprised of several parts could be printed in one go. This provides huge material and cost savings.
• Moving laser beam selectively sinters powdered polymer/ metal into successive layers.
Complex Geometry
• Materials: Thermoplastics, nylon, polyamide, polystyrene (elastomers), Metals
Unlike subtractive manufacturing methods, additive manufacturing allows the designer to create incredibly complex structures which would be otherwise impossible to make.
AdditiveOpportunities Group Brainstorming
Fields of Interest
Disability and Sport
Additive Focus
A group brainstorming session was used in order to identify a range of potential areas in which additive manufacturing could be used.
By identifying a range of potential areas for additive manufacturing, key areas of interest were selected.
A range of disabilities and sports were considered with a view to benefiting from additive manufacturing.
After careful consideration, the area of study chosen to benefit from additive manufacturing was disability within sport. The following pages detail the design process from concept generation to final design.
Medical Industry
• Disability • Orthotics
Industrial Application
• Implants
• Aerospace Industy • Automotive Inustry • Oil and Gas Industry
Home Use
• Home Printing • Interior Design
Consumer Products
• Art and Sculpture
Andrew Flynn
• Electronics • Sporting Products • Children’s Goods
PDE3
Brake Interface
Ice Axe Interface
Custom Sit Ski
ConceptSelection
Andrew Flynn
PDE3
Selction Process By looking at a range of disabilities within sport, three initial project concepts were created and considered. Each of these were evaluated individually and by a group and one was chosen to take forward.
Custom Sit Ski
Sit Ski Evaluation
Current sit skis use a hard plastic seat shell which can cause pain and discomfort. Using additive manufacturing a custom made, comfortable and secure seat could be created for the user.
The initial concept of this idea seemed appealing, however the need for this as a product is not great. Furthermore the need for additive manufacturing within this concept is limited.
Ice Axe Interface
Ice Axe Evaluation
Amputees that participate in ice climbing find it hard to interact with an ice axe. Additive manufacturing could be used to create a custom interface that will allow the amputee to use an ice axe.
This is a pressing issue for amputees who wish to ice climb however, after more research it appears there are many current solutions to this problem. Although not perfect, the current solutions would outweigh the benefit to cost ratio associated with this product.
Brake Interface
Brake Evaluation
Transradial amputees struggle to control the brakes on a bike. Using additive manufacturing a custom interface could be created that would allow the user to preform the basic functions of bike.
Despite a range of current solutions that allow amputees to cycle, there are none which give responsibilty and control back to the residual limb. This product will explore ways additive manufacturing can be used that will allow the user to do this.
UserProfile Creating a User Profile A range of cyclists of different levels and abilities were spoken to about their participation in cycling and what it meant to them. After some consideration it was clear that the cycling enthusiast would be targeted for the purpose of the project.
Pre Amputation
Post Amputation The Problem In the UK the NHS alone carry out approximately 5000 amputations each year. The world population of amputees is vast. For those whose past times are effected the psychological damage can be catastrophic. For the purpose of this project the focus will be on transradial amputees who are enthusiast cyclists. “Psychological distress is an inevitable consequence of amputation” -American Academy of Orthotics and Prosthetics.
Amputee’s Concerns: Cycling Enthusiast
• Lack of control
This person has been cycling their entire life. They have a true passion for the sport and is a part of their day to day routine. Cycling is used as an outlet for both physical and psychological needs. Romantic Cycle
Competetive Cycling
Family Cycle
Time Alone
• Humiliation • Residual limb becomes useless • Abnormal • No longer can relax
For a cycling enthusiast, cycling provides:
User Insights
• A way of socialising.
As an amputee, the user does not simply wish to be able to ride a bike again (as there are many solutions to this), they wish to ride a bike like they once did, pre amputation without looking abnormal. They wish to regain a feeling of purpose in their residual limb. To do this they need the means of providing control in place of a hand. This replacement would be used to control the brakes on a bike while allowing them to steer.
• Time to share with family and friends. • Thinking space and time alone. • Fitness. • Promotes healthy living. • A hobby.
Andrew Flynn
PDE3
Current Solutions
Key Insights
After doing some research the following three types of solutions were indentified.
Studying these current solutions a range of key user insights were identified.
Dual Brake System
• Alleviates purpose and control from residual limb • All control given to one hand • Learning four controls on one hand could be difficult
Home Made Prosthetic
• Dangerous homemade materials used • Can cause pain and discomfort to the user • No easy release system
Industry Prosthetic
• Very high price Transradial prosthetic can cost between £6,000 - £8,000
Andrew Flynn
• Prosthetic still looks abnormal • Prosthetic fit causes pain and discomfort
PDE3
The socket is created by taking a plaster cast of the stump or, more commonly today, of the liner worn over the stump, and then making a mould from the plaster cast. Prosthetics are usually replaced every 3 -4 years. Insights:
Plaster cast is inaccurate and outdated. Lack of quality and precision leads to regular replacement making it very expensive.
Current Prosthetic Problems A bad prosthetic fit will reduce the area of contact between the residual limb and socket. Without a full surface contact high pressure points occur between the socket and limb. This can cause pain and discomfort for the user. Air pockets can allow sweat to accumulate that can soften the skin. Ultimately, this is a frequent cause for skin rashes. This can cause a breakdown of the skin.
Movement within prosthetic fitting
CurrentSolutions
Current Prosthetic Fitting
Prosthetic Bruising
Insights: This pain and discomfort will be amplified with a sporting prosthetic as repetitive motions and sweating occur more.
Design Opportunity: Using a 3D scan of the arm a perfect full surface contact could be created using additive manufacturing.
Prosthetic Rashing
Leg Brake Interface
Mechanical Interface
Myoelectric Interface
SolutionSelection
Andrew Flynn
PDE3
My Brief Using additive manufacturing, design an interface that will give back a sense of control and purpose to the residual limb of a transradial amputee. The interface should allow the user to control the brakes of the bike while maintaining a firm control over the steering.
Myoelectric Interface
Myoelectric Evaluation
Using additive manufacturing, a perfect prosthetic to skIn contact could be created. Signals generated by nerve endings within the residual limb would be picked up and converted into electric signals by the additively made interface. These signals would control a hand like interface which would control the brakes.
This would provide an innovative solution to this product with clear advantages of additive technology, however there are two inherent problems. With myoelectric systems there is always a delay and there is no direct force feedback. When controlling the brakes on a bike, these problems could cause severe problems. Therefore the feasibility of this solution rendered it useless.
Mechanical Interface
Mechanical Evaluation
Taking a 3D scan of the arm, additive manufacturing could by used to create a perfect full surface contact prosthetic which would be used to control the brakes on a bike. The perfect fit socket would eliminate any pain and discomfort caused by current prosthetics.
A simple mechanical interface would provide an instant force feedback and has no inherent delay. Additive manufacturing would massively improve this product from current prosthetics creating a seamless interface for the user. This makes it an ideal choice for controlling the basic functions on a bike.
Leg Brake Interface
Leg Brake Evaluation
Taking a 3D scan of the legs, additive manufacturing could be used to create a made to fit mechanical brake activated by the squeezing of the thighs.
Despite being feasible, this solution would prove to be more dangerous as there is less dexterity in the legs. This product also had the least additive opportunities and was therefore not developed any further.
Pre Amputation
Conducting Research
Dr Barry Meadows
In order to design a sporting prosthetic it was important to understand some of the basic theory behind biomechanics. To do this a meeting was arranged with Dr Barry Meadows a specialist in this subject.
Meeting with Dr Meadows proved to be invaluable. He helped outline and define some of the basic but most important laws of biomechanics. Power, control and response were identified as being the foundations for any prosthetic design.
Damaged Control
BioMechanics
Body Power
System Control
Cut
Elbow Flexion
Elbow Flexion Control and dexterity in the elbow could be harnessed as part of the mechanism to control the prosthetic.
Bicep Power The bicep is a powerful muscle collection that provides high levels of proprioceptive feedback. It was decided that designing a mechanism around it would provide the desired user requirements.
Control
Control and dexterity come from a traffic of signals travelling back and forth from the brain to the moving limb. The limb must provide a feedback response through muscle and nerves in order to gauge the control. If muscles are damaged the response and therefore the control become unstable.
Push Power
Response
Andrew Flynn
PDE3
Push To Brake
Proprioceptive Response An awareness of the relative orientation of the body segments in space. In order for the body to function it must provide a proprioceptive feedback. The feedback allows the body to make alterations in its control. If this feedback is damaged the body will find it difficult to carry out even the most simple of functions.
Pre amputation the limb is powerful with a high level of control. As seen in the diagram, muscles in the forearm run from the elbow to the finger tips. In the case of a transradial amputee, amputation anywhere in this region will cause a reduction in power and control. This meant the prosthetic would have to harness the power and control from another region of the body.
Bicep Power
Harnessing Power
Power
For your body to have control it must first have the power and strength to do so. For an amputee, the effected residual limb will lack in power as muscles have been severed. It is important to harness power from a fully functioning part of the body.
Post Amputation
It was decided that a pushing motion would be tried as a method of controlling the brakes. Resistance to the motion would provide a force feedback to the bicep allowing the body a sense of proprioceptive control.
Push
ProtoTyping Testing and Prototyping In order to design a functioning prosthetic it was crucial to begin prototyping ideas. As this project could not be carried out with the assistance of an amputee it was imperative to empathise through prototypes. The following test outline the key insights acquired.
Flip The Brake
Push To Brake
The first task before carrying out prototyping was to flip the brake lever. This is easily done on most bikes simply by loosening a screw and rotating the brake lever into the desired position.
Simple testing was carried out with different tools to test how easy it was to activate the brake. Tests found, the bicep had more than enough power and control to activate the brake lever. An initial concern was that the steering would be effected by a pushing motion however no ill effect was found through testing.
Sharp Right Turn
Wrist Twist
Sharp Left Turn
End On Hold
The Design
Arm Bound
Pre Brake
Push To Brake
The Design
Arm Bound
Pull Against Handlebar
Push To Brake
Test 1
Standard Cycle A head camera was used to film the key movements around the wrist while cycling. It was found that there was little movement in the wrist and that the majority of the steering is controlled through the shoulders and weight shifts in the body.
Prototype 1
Wooden Claw The arm was bound to this device to limit the movement in the wrist. It was found that the device could wrest on the end of the handlebar to steer and apply weight. It could then easily be moved into position to brake while cycling. This device did not allow for a pulling motion when cycling up hill.
Prototype 2
Wooden Loop This prototype provided all the same functions as the first, however with the closed loop the user is able to apply a pulling force against the handlebars for cycling uphill. The basic functions of this prototype were taken fourth to be refined for the final design.
Andrew Flynn
PDE3
The final design was split into additive and non additively made components.
Firstly a scale drawing was made determining the dimensions of the product.
Scale Drawing
Final Design
Final Concept Design Taking the insights generated from prototyping a final concept design was created. This final design provides all the necessary functions needed to control a bike. By removing the bottom from the loop the product is easy to release if the user is to fall.
1. Carbon Fibre Claw 2. Rubber Hinge Socket 3. Additive Socket 4. Custom additive grips
Model Making
FinalDesign
Designing Components
Component 3 Created using 3D scan data, additively printed for the perfect prosthetic fit. Component 4
Andrew Flynn
PDE3
Custom made grips, made to order by the user to perfectly interact with their bike.
Model Testing
SLS Machine
Taking into consideration all the additive technologies initially researched, it was decided that SLS would be the most appropriate for the manufacture of the desired components. This was due to SLS being able to print a large range of materials.
Model Painting
Which Process?
A physical prototype was then made from the scale drawing to give an accurate representation of the final product. The final aesthetic of the prosthetic was modelled from current cycling gloves. This provides the user with a less abnormal look to current prosthetics. The final prototype carried out all the desired functions and therefore was ready to be made in Solidworks.
ProControl Ride.Unltd
The Problem • Transradial amputees struggle to control the brakes on a bike using their residual limb.
Key Insights • Transradial amputees retain much of their upper limb strength and control. • The experience of cycling is changed with the loss of function in one hand. • It is difficult to create a perfect, full surface contact finish when fitting prosthetics.
Andrew Flynn
PDE3
The Solution • ProControl - A high performance sporting prosthetic providing the perfect fit, allows the user to regain full control over the bike’s key functions; braking and steering.
ProDesign User Integrated Design
Custom fit additive socket provides a full surface contact finish which eliminates any pain and discomfort caused by traditional methods of prosthetic fitting.
To allow the product to be used with more than one bike Ride.Unltd provide an online grip design service. The user simply enters the dimensions of their bike’s handlebars and a set of custom grips are generated. These are additively made by the SLS machine and then sent to the user ready to be used.
Grip Generator
Socket Cross Section
Custom Grips
Additive Socket
Additive Socket
Ride.Unltd ENTER X DIMENSION: __________________ ENTER Y DIMENSION: __________________
Ride.Unltd
Full Contact Fit
ENTER X DIMENSION: _______5.3________
Andrew Flynn
User Interface
ENTER Y DIMENSION: _______6.7________
PDE3
ProService
User Interaction
The User
Initial Problem
Ride.Unltd ENTER X DIMENSION: _______5.3________ ENTER Y DIMENSION: _______6.7________
3D Arm Scan
Customised Grip
Ride. Unltd
Consultant Meeting
Product Manufacture
Mass Production
CAD Technician
SLS Machine
Sleeve Made
Andrew Flynn
PDE3
3D Print
ProConstruction
A B C
D A Silicon Sleeve
• Silicon sleeve used to provide an ideal suction fit when wearing the prosthetic. It also provides the user with increased comfort.
F Brake Lever
• For the ProControl to work the brake lever must be adjusted. Firstly, the brake lever is rotated to the inside of the handlebar. Secondly, the lever is flipped horizontally. This allows the user to easily navigate from the handlebar to the brake lever and exert a pushing force when applying the brakes.
E
F
B Prosthetic Socket
• Using additive manufacturing the socket provides the perfect suction fit to the user. Made from polypropylene, the material’s flexible nature gives the user a large range of motion.
C Rubber Socket
• Made from Butyl rubber, this second socket acts as a living hinge allowing for 360° of movement. This material also acts as a shock absorber, damping the force applied to the residual limb.
D Carbon Fibre Claw
• Hexcel carbon fibre ensures this component gives the user enough strength and flex to take control of the bike. Four key intuitive functions allow the user to both steer and activate the brakes.
E Custom Grips • Additively manufactured, the design of these grips are customised by the user in order to fit the dimensions of their bike. The grips are interchangeable to allow the user to switch between grips for different bikes.
Andrew Flynn
PDE3
ProFunction
1 Full Weight
2 Full pulling force
This position provides the user with a means of steering and the option to put their full weight down on the handlebars. This would be adopted when standing on the bike with a large downward load.
The front grip provides the user with the ability to pull against the handlebars. This could be used when a reaction force to the pedals needs to be applied, for example, when cycling uphill.
Lock Mechanism The lock mechanism for this prosthetic took inspiration from current prosthetic locks. The user feeds the residual limb, with silicon sleeve on, into the additive socket. The socket is then inserted into the rubber hinge along a guide groove. Once fully inserted the user turns their arm through 90째 locking the arm securely into place. The carbon fibre claw is then fitted to the rubber hinge in a similar fashion.
3 Ready To Brake
4 Lift + Push To Brake
In this position the user is ready to brake but maintains the ability to steer. As seen in the side profile at the foot of the page the grip is designed to provide a small amount of purchase for steering.
130째 Hold The custom grip is designed to fit round 130째 of the handle bar. This way it provides enough grip when, pulling against the handlebar and pushing the handlebar, for it not to slip.
Easy Release The prosthetic is designed in such a way that if the user is to fall off the bike the prosthetic simply comes free.
Andrew Flynn
PDE3
0째
13
When the user is ready to brake they simply raise their arm a small amount providing clearance from the grip. They then push forward with their arm the desired amount causing the brakes to activate.