Revolve Magazine 2022 Issue 1 by Revolve NTNU

MAGAZINE

ISSUE 1, 2022

REVOLVE

Contents 4

Atmos to the atmosphere

Luna shoots for the stars

This year’s challenge

get to know Control Systems

Bertel O. Steen

Get to know Driver Interface

BDO

Photo gallery

NORBIT

Crossword

Radionor

Dassault

Deep Dive: Master Theses

Team Overview

18 16

Editor-in-Chief Mia Elisenberg T: +47 90 12 60 17 E: mia.elisenberg@revolve.no Project Manager Sigurd Werner-Torgersen T: +47 48 25 08 28 E: sigurd.wernertorgersen@revolve.no

Cover Photo By: Trond He

Head of Marketing & Finance Aida Angell T: +47 93 09 99 29 E: aida.angell@revolve.no

Graphic Designer Mia Elisenberg T: +47 90 12 60 17 E: mia.elisenberg@revolve.no

Mia Elisenberg Editor-in-Chief

New project year, new team, a new set of competition rules to follow, and a brand new car to build. This project year is bringing new challenges and more opportunities. In this issue, we take a look at the summer with Team 2021 with our cars Luna and Atmos, and then dive this year’s new systems.

36 44

Revolve NTNU E: post@revolve.no Revolve NTNU, S. P. Andersens veg 3, c/o MTP Valgrinda, 7031 Trondheim, Norway 3

Atmos to the atmosphere Photo: Mia Elisenberg (Revolve NTNU)

In July, our autonomous car, Atmos, and the Driverless Vehicle (DV) groups Mechatronics and Autonomous Systems went to Lillesand, Norway to attend the Lillesand Test Event with other Scandinavian Formula Student teams. This made us able to test our car all day and night, fixing software bugs and other electrical and mechanical issues before going to Formula Student Germany (FSG).

The goal of Team 2021 was to finish all dynamic events at the competition, in addition to focusing on car reliability. Our dedicated DV team pushed themselves and the Atmos to perform the best she ever has done to this day, resulting in finishing 4/5 dynamic events. We are incredibly proud of having earned 5th place overall in FSG!

7 Photo: Revolve NTNU and Formula Student Germany – Wintermantel, Doehla

Luna shoots for the stars Photo: Formula Student Germany – Shidharthade

Our four-wheel drive electric car, Luna, travelled to Hungary to compete in Formula Student East (FS East) and to Germany to compete in FSG. Designing, producing and building Luna was not without challenges because of COVID-19. Despite the hickups and challenges along the way, we are incredibly proud of how the team and our sponsors made us able to produce

our fastest and lightest car yet. Luna weighs only 157 kg and produces about 115 horse power. This summer, we earned 3rd place in Engineering Design at FS East and 1st place in Skid Pad at FSG. Our 2021 car showed us what we can accomplish as long as we work together! 9

10 Photo: Revolve NTNU and Formula Student Germany – Partenfelder, Wintermantel

12 Photo: Revolve NTNU, Formula Student East and Formula Student Germany – Doehla

14 Photo: Trond He (Revolve NTNU)

T H I S YEA R’S CHAL L ENG E

CR E AT I NG A SIN G L E CA R T H AT CAN D RIV E BOTH M A N UA L LY A ND AUTO NO MO US LY

GET TO KNOW:

CONT ROL SYS TE MS Making the vehicle behave optimally on the track, both with a driver in the vehicle and when driving autonomously, is the main responsibility of the Control Systems group. The group is in charge of making use of the four wheel drive electric powertrain featured in our vehicles, pushing it to the limit of what is physically possible, during acceleration, deceleration and cornering. To achieve this, the group utilizes advanced control methods, state estimation, optimization techniques and modeling in one of the most groundbreaking fields in motorsport. Torque Vectoring is one of the control systems developed by the group, which determines the optimal motor force for each wheel several hundred times per second, to take full advantage of the available grip produced by the tires, to be able to navigate the racetrack as fast as possible. To be able to do this, the algorithm uses a wide range of sensor data collected by the Sensor Broadcasting System. The Torque Vectoring algorithm runs on the Vehicle Control Unit, developed by the Embedded Electronics group.

Vehicle modeling and simulation is one the cornerstones in the group, which is used for both development and testing of the different control systems developed by the group, in addition to making good design choices for the next vehicle based on lap time simulation. This year, we’re working on development of our own Vehicle Dynamics Simulator, which will accurately model our vehicle in addition to having the same communication interface as our vehicle. With this simulator, we will be able to do hardware-in-the-loop (HIL) testing of the whole vehicle pipeline, before we start driving with our finished vehicle, which hopefully will be saving valuable testing time during the summer months.

Group Leader: Control Systems

passive damper, improving the groundtire interaction and stabilizing the aerodynamic platform, counteracting displacements in roll, pitch and heave.

Figure 3: Adaptive Damper.

Figure 2: Double Track Model.

Figure 1: The Vehicle Control Unit (VCU).

Eskil Mogstad

The group is also in charge of the development of adaptive dampers. The adaptive dampers are filled with a magnetorheological fluid, which changes viscosity when exposed to a magnetic field. A coil is built into the adaptive damper, which creates a magnetic field when current flows through it. The Damper Control Unit is able to control the current in this coil, to change the damper characteristics on the go on the track, achieving better control than what is possible with a standard 16

The group collaborates with many groups in the organization. The control systems developed by the group end up running on circuit boards developed by the Embedded Electronics group. Further, the group collaborates a lot with the Embedded Electronics group, determining the sensors needed for the vehicle, both for driving and for validation. The group has several exciting projects with the Autonomous Systems group this year, as we are creating a unified vehicle for the first time in Revolve NTNUs history, which will be able to be driven both manually and autonomously. The previously mentioned Vehicle Dynamics Simulator is a good example of this, which will be used to test the control systems before

Figure 4: Torque Vectoring Block Diagram.

The group has several exciting projects with the Autonomous Systems group this year, as we are creating a unified vehicle for the first time in Revolve NTNUs history, which will be able to be driven both manually and autonomously. The previously mentioned Vehicle Dynamics Simulator is a good example of this, which will be used to test the control systems before the vehicle is finished. Additionally, we will be unifying State Estimation, a central part of both Torque Vectoring algorithm and the Autonomous Pipeline, and run this on the Vehicle Control Unit, achieving higher update rates and avoiding duplication of functionality in different systems.

Figure 5: Torque Vectoring on NOVA.

VI SØKER STUDENTER TIL INTERNSHIP I

B ERTE L O. S TEEN , OTTO O G F LEK S Bilbransjen er inne i den største og mest omfattende transformasjonen i bransjens historie hvor flere megatrender treffer bransjen samtidig. Elektrifisering, nye mobilitetsløsninger, nye oppkoblede og etter hvert selvkjørende biler og flere andre trender medfører både store endringer i dag og vil medføre enda større endringer fremover. Vi i Bertel O. Steen, Otto og Fleks rigger oss for å spille en viktig rolle og lede an i utviklingen av morgendagens mobilitetsløsninger. Vi skal gå i bresjen på temaer som blant annet mobilitet og oppkoblede biler («connected cars») i en stadig mer elektrifisert transporthverdag. Dette var noe av årsaken til at Bertel O. Steen etablerte Otto og Fleks som spin-offs fra hovedvirksomheten. Kanskje har du bestilt deg et bilabonnement gjennom Fleks eller leid deg bil gjennom Otto? For å lykkes med vår satsing er vi avhengig av dyktige folk og vi søker etter studenter til internship innenfor en rekke roller: • • • • •

Utviklere Data scientists Data engineers Forretningsanalytikere ++

Beskrivelse av arbeidsoppgaver Som intern vil du inngå som en del av det teamet der dine evner egner seg best. Vi søker etter flere kandidater som enten vil bli plassert i utviklermiljøene hos Fleks eller Otto eller som data engineer, data scientist eller analytiker i avdelingen Data og Innsikt i Bertel O. Steen. Du vil jobbe som en integrert del av teamet hvor du utplasseres, og hos oss vil du få muligheten til å bryne deg på å løse virkelige forretningsproblemer gjennom koding. Vi ser etter deg som .. er sterk på utvikling, gjerne applikasjonsutvikling, .. er glad i å lage struktur av store uhåndterlige datamengder, .. elsker å gjøre om data til innsikt, .. mener at beslutninger bør være basert på gode analyser (datadrevne beslutninger), .. har lidenskap for maskinlæring og kunstig intelligens, .. eller bare elsker å kode. Da vi ser etter flere ulike roller, oppfordrer vi alle som treffes av en eller flere av beskrivelsene ovenfor og/ eller har sterk interesse for å løse reelle forretningsproblemer gjennom koding til å søke!

Vi søker etter studenter i slutten av en bachelorgrad eller som har påbegynt mastergrad. Du har muligheten til å jobbe deltid parallelt med studier og mulighet for høyere arbeidsbelastning gjennom sommeren. Varighet og omfang blir tilpasset studiesituasjonen. Videre er det ønskelig at du har teknisk kompetanse og erfaring i bruk av ulike verktøy, metoder og modeller til bruk i utvikling, f.eks. smidig utvikling og DevOps. Pluss dersom du har praktisk erfaring med utvikling, implementering, skalering og verdirealisering av produkter, tjenester, applikasjoner etc. Som person er du analytisk og løsningsorientert. Du er genuint nysgjerrig, med et ønske om å lære! Du liker å tilegne deg kunnskap raskt, og dele den med andre. Du er selvdreven, men innehar samtidig gode kommunikasjonsog samarbeidsevner da du skal jobbe i team. I tillegg ser vi etter deg som liker både teknologi i seg selv, og hvilke endringer den kan skape.

GET TO KNOW:

D RIV E R I NT E RFACE For many years Revolve has tried to emphasize the driver’s environment and how the overall feedback of the car impacts performance. With this year’s car, we are also combining two vehicles into one, the manual and autonomous, and with that comes new challenges. Here, Driver Interface is tasked with making the steering and braking system work in both modes be reliable, and at the same time be noninterfering with the drivers’ intuition. The group consists of four members, where one is the group leader responsible for the progress in the group, and the others are technical members accountable for their systems. The systems in Driver Interface are: Ergonomics, Pedal box, and Steering System. To design and produce the best possible solutions for the drivers, the responsible person takes the casting of the drivers and use the simulator to

decide on better design solutions. The Pedal box designs and develops the acceleration pedal and the braking system, which works autonomously and manually. One of the biggest challenges for this year’s braking pedal is the placement of actuators with enough piston area to get the required pressure on the cylinder. There are several concepts, but many are too spacious and heavy. Since the system is located in the front and integrated on the pedal, we have to take measures so that the center of gravity isn’t moved too far forward. Steering system is the second mechanical system in Driver Interface and is tasked with making the manual and autonomous steering system. Previously this position was split in two, so the workload for this year increased, and it has become more of a mechatronics position. One of the

Simen Tufte

Group Leader: Driver Interface

parts we want to do a redesign of is our steering rack. We have used the zRack +S, but getting hold of it has is a challenge. Our goal is, therefore, to find a good tooth profile and manufacture the entirety ourselves. The last system is Ergonomics, and it is not a new position to the team, but more a restructure. It has usually been on the Chassi group, but with a more significant focus on the driver, it was a push to make it a stand-alone role and give it more resources. Ergonomics is responsible for the seat, steering wheel, flange and other surfaces directly impacted by the drivers’ operation of the car, such as the dasboard and harness. For this project year, we want to upgrade the simulator and conduct user testing of 3D-printed grips, heel caps, and springs for the braking pedal to optimize the driver performance through human-centered design.

For this project year, our goal is to have the total weight of all components on the group below 12.5kg, and at the same time have the actuators perform with ASB system with more than 100bar of pressure and change in steering angle great enough to turn in skid while driving at 30km/h. And our main focus is as follows; “Driver interface’s main focus is to increase the cockpit design and allow for driver performance to not be limited by design. This is to be reached without risking the reliability of the car and normal driver intuition.” We have talked with alumni so far and gotten a headstart on the design process to reach our goal. To get some real numbers and validation, we also initiated a test of Atmos (previous DV-car) to test the steering torque required to turn the wheel and see how the car braked in autonomous mode. Going forward, we will look into the full integration of our systems in the car. We will also pick and decide the best combination of brake calipers and cylinders through vigorous testing, to optimize our chances at winning FSG.

We are thrilled for this year and look forward to competing!

BDO AND REVOLVE NTNU –

I N NOVAT I N G TOGE T HE R For BDO, cooperating with Revolve NTNU is a chance to support the development of important technology, and at the same time help the people behind the innovations, so they can succeed. Change and development are key words for BDO. Since our founding in 1963, the BDO story has been one of continuous response to our clients’ and our people’s ever-changing needs. In the subsequent 50+ years, BDO has grown into a US$8 billion+ business, operating in 167 countries, with over 80 000 employees. In Norway, we are about 1700 employees, and we have 70 offices countrywide, with over 43 000 customers. Our international “Why” is “People helping people achieve their dreams,” which can signal our determination

Anne-Katrine Ekseth Hollum Market Manager BDO MidtNord Text

Ole M. Wold Photo

to both be an integral part of the local community, and at the same time have the knowledge and platforms that can elevate the different businesses to new heights. The cooperation with Revolve NTNU is a local initiative for the BDO office in Trondheim. Trondheim is the technology capital in Norway, so supporting local tech businesses and NTNU is important to us. We are seeing some good results in making BDO generally more known and more attractive as an employer, since the cooperation with Revolve started in 2018. Amongst other things, we use the Revolve network and their digital channels to recruit a new breed of employees for our new teams Business Analytics, Robotics and Startups/ Scaleups. Revolve can help us find the right candidates for the future!

Above all, we will continue to deliver the exceptional client service for which we are known. Technical excellence is a given, but our customer experience is embedded in our strategy and undertaken on a truly global and local level. In that context; the relationship a big cooperation like BDO can have with Revolve NTNU in Trondheim, can help both parties evolve and reach our goals in the future.

23 Photo: Trond He (Revolve NTNU)

24 Photo: Vegard Strand (Revolve NTNU)

30 Photo: Trond He (Revolve NTNU)

NORBIT –

A LWAYS GOIN G TH E E XT R A M I L E When the first COVID wave hit it was demanding for most of us. Norway closed down and we were asked to stay at home. Revolve NTNU experienced a really tough challenge, we lost access to the production facilities we have used in all previous years. We needed to reorganize and to find a suitable location nearby, our first thought were to ask NORBIT for help.

Revolve a lot over the years. By providing microscopes and soldering equipment, they have massively improved our electronic production process. NORBIT has also helped in the

NORBIT has been a longtime sponsor of Revolve NTNU. Headquartered in Trondheim, NORBIT provides tailored technology in many different fields; Oceans for global maritime markets, Connectivity for asset identification, monitoring, tracking, and Product Innovation & Realization for R&D services and contracts manufacturing to critical customers. NORBIT is one of Norway’s fastestgrowing businesses and has developed a global network of partners. Intending to explore more, NORBIT develops both commonplace and highly specialized items, like sonar solutions for mapping the ocean floor. You are probably an owner of a NORBIT product yourself: The AutoPASS tag in your car is probably developed by NORBIT. By making advanced test equipment available, NORBIT has supported

design process by reviewing our PCB layouts and giving many tips to improve our electronics. For the 2021 team, however, NORBIT was crucial in making the car. Due to the covid-19 pandemic, we lost access

Håkon Liverud

Chief Electrical Engineer

to the production facilities we have used in the previous years. We were desperate to find a new location to produce our PCBs. As we usually make hundreds of fully soldered PCBs, your standard hand soldering equipment would not be enough. Luckily, we had NORBIT as a sponsor! We immediately called to NORBIT and explained our situation, NORBIT rapidly cleaned two of their offices and placed a soldering oven, a pick and place machine, and other equipment for us to loan. The embedded electronics group spent the next few weeks producing and soldering PCBs at NORBIT’s office. The equipment was of excellent quality, and the PCBs turned out fantastic. Without NORBIT, their flexibility and quick response in a very critical situation, there is a big chance we would not have made a 2021 car. We are very grateful for our strong partnership and hope to continue working together for many years to come. NORBIT’s specialty is to help companies with their competence and equipment and speaking as someone who has experienced firsthand; we strongly recommend NORBIT’s services!

HOW WELL DO YOU KNOW THE TEAM? 1

3 4

7 8

13 14

2. Name of the 2021 Driverless Vehicle 4. VCU is short for 6. Event we won in FSG 2021 9. Camilla’s master thesis 12. Name of one of the groups 14. Name of a main sponsor 15. 3D modelling softwrae 16. Important in Henrik’s master thesis

Down

1. Main system in Marius’ master thesis 3. Name of the 2021 Electric Vehicle 5. CAD is short for 7. Name of the racetrack in FSG (also a Formula racetrack) 8. Career fair organizaed by Revolve NTNU 10. Control system that helps the driver 11. Name of a main sponsor 13. One of Revolve NTNU’s key values

1. Adaptive dampers; 2. Atmos; 3. Luna; 4. Vehicle Control Unit; 5. Computer Aided Design; 6. Skidpad; 7. Hockenheimring; 8. RevolveDagen; 9. Inverter; 10. Torque vectoring; 11. Bertel O. Steen; 12. Driver Interface; 13. Innovative; 14. Kongsberg Gruppen; 15. Solidworks; 16. Batteries

Across

RADIONOR –

MAKING U S UNMATCHED

Håkon Liverud

Chief Electrical Engineer

No competitor can match our telemetry solution. Revolve NTNU could not have achieved success without support from Radionor sharing their competence and equipment generously. They have onboarded former Revolve NTNU members giving them exciting career opportunities.

Radionor Communications, headquartered in Trondheim, develops next-generation tactical broadband data links based on phased array antennas. The technology provides unmatched range and stability and is ideal for high-mobility applications. The technology has been proven to offer unique performance for tactical operations for manned and unmanned aircraft, vessels, vehicles, and mancarried equipment. With customers like the Norwegian Armed Forces, Rohde & Schwarz, Kongsberg, their products have demonstrated unique technological capabilities on an international level. Their recent nomination as one of six for the Norwegian Tech Awards 2021 proves they are at the bleeding edge of radio communication technology.

trackside while driving. After the test drives, all technical members of Revolve NTNU uses the data to analyze how to improve the performance and reliability of the system. The communication between the car and the trackside is two-way, enabling tuning of the car by sending parameters over the telemetry, saving valuable testing time.

Radionor is a long-term and vital sponsor of Revolve NTNU. By loaning the project Cordis Radio Eye phased array radios and sharing essential competence and giving crucial usage tips, Revolve NTNU is unmatched by other competitors with our unique telemetry solution.

Not struggling with range, capacity, or data loss while driving gives Revolve NTNU a substantial competitive advantage. Having reliable equipment we can trust is a massive relief, creates effectiveness, and drastically reduces risks.

Our cars contain a CRE2-144-LW which sends all of the car’s data, like the motor temperature, to a CRE2-179 base station. This is done to make sure we are within safe limits; otherwise, a significant risk would be an overheated motor. Another example is the velocity data and the brake pedal position, which is used to analyze how the driver is performing and may drive even faster, giving Revolve NTNU a competitive advantage. This data includes information from the hundreds of sensors on the car, which usually accumulates to over 100 gigabytes of data every season. The alternative communication channel Wi-Fi would be suboptimal as it would not support the required range and ease of setup. The radio link is IP-based, enabling live data visualization for multiple team members simultaneously on the

Radionor’s solid reputation, exciting, innovative environment, and worldleading technology have attracted multiple Revolve NTNU alumni, who now have a permanent job at Radionor. The possibility of being part of a creative team and the opportunity to work within your passion for electronics and communication technology creates exciting career development.

The Revolve NTNU team is humble and very grateful. We are very much looking forward to continuing the partnership with Radionor.

A GR E AT CA R START S W I TH GREAT SOFTWA RE Conceptualizing, designing, and building a formula-style race car in less than a year is an enormous task. Throughout Revolve NTNUs history, we have always tried to out-perform our last vehicle, pushing the limits even harder. For the mechanical part of the team, this means developing parts and concepts which surpass previous designs. This demands us to be able to quickly make a CAD (computer-aided design) of the concept - parts and/or assemblies - and check whether it is feasible or not. We spend hours upon hours in Dassult’s SolidWorks to ensure we do not get any surprises once the parts are in our hands, ready to be installed on the car. In this powerful 3D-modelling software, we can create and assemble our parts to check if everything fits - statically and dynamically. When we are satisfied with our designs, Solidworks helps us to construct our technical drawings. Solidworks enables us to intuitively implement complex geometric tolerances and accurate dimensioning that are up to the standards of our professional machining sponsors in the industry. Accurate tolerancing is essential when manufacturing high precious parts such as gears, bearing surfaces and drive shafts. Pushing the limits in racing often means pushing the weight down. This is down to pure physics, as you need to accelerate the mass of the car, with a limited grip (force). Lowering the mass is not always easy; at some point, you will look at the part and think, “will this tiny piece withstand all the loads it is

subjected to?”. In 2021, we had one of the lightest cars on the grid, measuring 157,5 kg, yet, we had no structural failures. This is due to many reasons, but one of them is us being able to trust our stress analyses and being confident that they give us a realistic image of the systems real-life behaviour. Our biggest conceptual change from the 2020 season to the 2021 season was the tire change: from 13” to 10” tires. This meant we had to redesign the rims, in which we decided to go for a CFRP rim. Utilizing Dassaults Isight software, in cooperation with Abaqus, enabled us to optimize the fibre layups to achieve a stiff and strong rim while still being lightweight. This technique was also used on our carbon fiber A-arms, as we feared that the increased loads in the suspension could be devastating. Our main software for strength analysis is the Dassault Simulia products. As aforementioned, we used Isight for layup optimization. This is linked with Abaqus, a product from the same package, where we conduct the stress analyses. The product is so powerful that we are still to this day discovering new ways of improving and simplifying our simulations while maintaining confidence in their reliability. We managed to model our suspension in a new way which enabled us to cut down the number of steps to reach the requested measurements, from six to one! Not only did this fast forward our simulations, but we were able to use these measurements and numbers to design our car. 36

Sondre Audal (right)

Structural Suspension Outboard

Ola Flåskjer (left) Upright

Racing consists of numerous demanding dynamic load cases that push our parts to the limit. It is often quite challenging to visualize the load paths when you combine cornering, road bump, braking and acceleration load cases into one. To help us create structures that are as light as possible while being as stiff as they need to be, we use Tosca Structure to perform topology optimization. An easy to use, intuitive plug-in to Abaqus, Tosca Structure has enabled us to optimize the structure of our uprights. This powerful software gets the job done, whether they are 3D-printed or machined, made in aluminium alloys or titanium. We then use SolidWorks to model the topology result and Abaqus to verify the stresses and compliances. In short, Dassault software is a large part of why Revolve can design a competitive Formula Student car that performs among the very best in the world. Taking in new members that are completely inexperienced in CAD and FEM software, and in the span of 6 months, design parts that go on our car is a testament to the quality and ease of use of the Dassault software library.

We hope to continue this great cooperation for a long time!

DEEP DIVE

M ASTER TH ES ES Each year, several of our team members write their Bachelor or Master thesis for the team. In this issue, we delve deeper into the world of Embedded Electronics and Control Systems.

Camilla Greve Hartviksen

Marius von Hafenbrädl

Embedded Electronics Inverter Control & Software

Control Systems Adaptive Dampers

MASTER PWM Switching Schemes for Automotive SiC MOSFET Inverter

Camilla Greve Hartviksen Embedded Electronics Inverter Control & Software

I’m a 25 year old girl from a small farm in the Lofoten Islands. I have always thought Revolve NTNU was the toughest, most challenging and most awesome organization a student could join, and this year I finally had the guts to apply for a position here. It’s been the best decision I’ve made in all of my years of studying.

The inverter is the most complex electric system, and in my humble opinion, the coolest system on the car. It’s responsible for transforming the DC current coming out of our accumulator into 3-phase AC-current for our four IPMSMs (interior permanent magnet synchronous motors). The term inverter is an umbrella term that covers multiple subsystems, including four individual inverters for each motor on each wheel. Most importantly, our inverter contains our main control card that runs our motor control algorithm. It takes measurements on the phase currents and from the motor encoder as input, and uses FOC (field oriented control) to output a PWM (pulse width modulation) wave for each of the four inverters. Each individual inverter contains three half bridge MOSFETs that act like switches, and can be turned on and off and create square waves, see figure 1. When switched fast enough, the three half bridges can create sinusoidal currents that go into the PMSM, see figure 2. By controlling the PWM’s duty cycle, we can change the input voltage and speed of the motors, which can go up to 20krpm.

IN V ERT ER ? I H A RD LY K N OW H ER

Figure 1: A very simple figure illustrating three half bridges sending current through to the stator, with a corresponding rotor with one pole pair. For reference, Revolve NTNU uses a motor with four pole pairs.

Figure 2: The three phase currents shown in sinusoidal and in their respective square wave form. 40

MASTER PWM Switching Schemes for Automotive SiC MOSFET Inverter

Figure 3: A block diagram showing the feedback regulation of the speed through the inverter and the motors using the Clarke-Park transform and PI-controllers.

My project- and master thesis will consist upon improving the software side of things on the inverter. This fall, I will improve our inter-process communication on our control card. I want to implement fast and reliable communication between the cores on our MPSoC, and also run a response time and schedulability analysis to make sure the communication won’t cause any issues. Furthermore, I will boot up the cores from memory. Thus my project thesis will provide plenty of challenges revolving around real-time systems. For my master thesis this upcoming spring, my objective is to develop an improved motor control algorithm for our newest self-developed inverter. I will work on developing a motor control system and a motor model in MATLAB/ Simulink, and finally I will test and validate what I implemented on actual

hardware, and compare this to simulated results. Figure 3 shows a closed loop motor control system that will be quite similar to what I will implement. As mentioned prior, the inverter is a very complex piece of software and hardware, and it took four years for Revolve to self-develop its first inverter. The generation I will work on this year is more commonly known as the I21 here in Revolve, and it has a lot of remaining work and testing on it before it is ready to be placed on a car. For the competition in the summer of 2022, we will aim to have our last functioning generation inverter, the I19, fine tuned and on the test ready car in May. We will of course work hard to try to get the I21 on the car, but our highest priority is reliability. No matter what, the car will have an inverter designed and developed by Revolve NTNU!

MASTER A performance comparison of control strategies for a semi-active suspension

Marius von Hafenbrädl Control Systems Adaptive Dampers

I am 23 years old and come from a place called Asker, 20 minutes of driving outside Oslo. This is my third year at Revolve NTNU. After two years in management positions, first as a leader for the “Mechatronics” group in 2020 and then as the chief electrical engineer in 2021, I am very excited about doing my master thesis as a technical member in Revolve NTNU. What I believe is special about doing a master thesis here, is that you are fully responsible for defining your own project, get to experience the full product development cycle, and implement, test and validate your solution in the real world.

T H E PU RS U I T O SE M I -AC T I V E SU S PENS I O N

What are semi-active dampers? The use of springs to permit vertical movement and improve the ride of a vehicle goes back to the days where people were using horse-drawn carriages and was adopted early in the history of the automobile. The function of the dampers, or shock absorbers in which they are also called, is to suppress the oscillations introduced by the springs and control the vehicle’s motion due to longitudinal and lateral acceleration. There are multiple ways to design a damper, and the world has since its introduction in 1902 seen a lot of brilliant and straight awful variations. What they have in common is that they, in some way, dissipate heat energy from the mechanical energy imposed on the damper. The most common way of doing this is called viscous damping and is achieved by traversing a piston through a fluid with viscosity. Figure 1 shows the movement of the piston (blue arrow) and the damper fluid (red arrow) in compression and extension. As the dampers in the automotive

and high-speed corners inducing vehicle movement. As for most tunable parameters in racing, improving the performance in one scenario will lower the performance in another, making the tuning process about finding the right compromise. Here is where semi-active (adaptive) dampers come in handy. The basic principle is that they can adjust the damper characteristics while driving and thus open the possibility of not having to make a compromise. Figure 1: When the damper is compressed, the piston will be pushed downward and forces the fluid underneath to move upwards through the slot in the piston. The resulting viscous damping force is proportional to the velocity of the piston. The same happens in extension, often called rebound, but with opposite directions.

industry evolved, it became possible to adjust the desired damper response for different driving scenarios. Most of these driving scenarios are usually represented along a standard race track, such as low- and high-speed bumps, vibrations covering a large spectrum

MR dampers Adaptive dampers can be realised in multiple ways. We chose to make Magnetorheological(MR) dampers because of their low energy requirements, substantial operating range and low weight. An MR damper uses a magnetorheological fluid(MRF) to adjust the damper characteristics with electromagnetism. As figure 2 shows the MRF rearranges the structure of magnetic particles within the fluid when affected by a magnetic field and thus changes the apparent fluid viscosity.

MASTER A performance comparison of control strategies for a semi-active suspension

OF A Figure 4

Figure 3: A quarter-car model is pretty much, as the name suggests, a representation of a quarter vehicle and is one of the simplest and most widely used models in vehicle and suspension analyses.

Figure 2

This change directly affects the damper characteristics. Hence, by adjusting the magnetic field strength we can adjust how stiff or soft we want the damping response to be.

The history of adaptive dampers (AD) in Revolve NTNU The development of the MR-damper in Revolve NTNU was started in 2018. During the first year, a prototype damper, a quarter-car (figure 3) test rig and the first revision of the damper control unit was made. The second year of development resulted in a new revision of the MR-damper and the damper control unit. In addition, modelling and control strategies were

looked more into. The previous project year, the third year in the life of our MR-damper project, was mostly about the modelling of a damper and control systems to obtain the desired current thus desired damper force. There was also made huge improvements to the damper control unit. Machining the dampers proved to be a big challenge and resulted in further use of the prototype from 2018/2019. How I am building on the previous work As I hope the reader understands, previous members in Revolve NTNU have put in a fantastic effort to make the fundament on which I have the pleasure of continuing building upon. What I will do this fall, and base my project thesis on, is investigating differences in laptime for multiple control strategies in simulation. Briefly, this involves choosing and implementing different control systems in MATLAB/Simulink and integrating

them with our vehicle model within the simulation environment. After implementing the control strategies, I will make the simulation run the events of the Formula Student competition and compare and analyse the resulting vehicle performance. In parallel with the simulations, I am also getting the latest revision of the MR-damper prototype machined, assembled and ready to start testing in early January 2022. The control unit has proved itself reliable, well-performing and will stay the same. Having all I need to start testing the dampers in our quarter-car test rig, the beginning of the new year will be dedicated to system testing and identification. For my master thesis this upcoming spring, the goal is to make a solid model of the damper through the system identification, and design a control system able to maximize the road holding capabilities while still having the vehicle motion restrained. What I would like to accomplish this year is to get the semi-active dampers finalised enough to be used on our new racecar and show what 6 man-years of effort can result in.

SAY HEL LO TO T H I S YEAR’ S T E A M !

THE BOARD

Project Manager

Deputy Project Manager

Head of Marketing & Finance

Head of Production

Chief Electrical Engineer

Chief Mechanical Engineer

Sigurd Werner-Torgersen

Anders Oust

Kaja Erfjord

Håkon Liverud

Aida Angell

Asbjørn Verlo

MARKET ING

Head of Marketing & Finance

Financial Accountant

Key Account Manager

Event Manager

Graphic Designer

Video- & Photographer

Aida Angell

Vårild Engmark Øyulvstad

Social Media Manager Trond He

Ingerid Risvik

Mia Elisenberg

Web Developer

Sivaranjith Sivarasa

Sindre Nygaard Engen

Vegard Strand

EMBEDDED ELECTRONICS

Group Leader

Niklas Strømsnes

Dashboard, Processing Unit & LIDAR William Moriggi

Vehicle Control Unit & Autonomous Control Unit Andreas Larsen

Sensors

Accumulator Management System

Inverter Control & Software

Inverter Hardware & Software

Jostein Brovold

Camilla Hartviksen

Safety Systems Njål Rundereim

Henrik Grytten

Per Gundersen Lund

POWER SYSTEMS

Group Leader

Elias Helle Kalland

Motor Validation CAD Endre Stedje

Accumulator Responsible

Accumulator CAD

Cooling

Wire Harness CAD

Joakim Saugen

Maria Schubring

Caleb Wilson Sy

Tom-Are Eidal

AERODYNAMICS

Group Leader

Fasteners & Fibersim

Composite Production

Aerodynamic Designer

Børge Nyland

Herman Fjellestad

Inge Eliassen

Kris Gabriel

CHASSIS

Group Leader

Christina Austestad Hardeland

SES

Adithya Arun

Chassis Design

Hemund Engmark Øyulvstad

Simulation & IA

Martin Bechmann-Hansen 49

Henrik Grønlund

Aksel Kvamme Aase

SUSPENSION & POWERTRAIN

Group Leader

Upright

Carl Oscar Rokkones

Ola Flåskjer

Structural Suspension Inboard

Structural Suspension Outboard

Petter Vang

Sondre Audal

Brake System Henrik Døsvik

Vehicle Dynamics Audun Olsen

Hub & Gearbox

Marius Dørmenen

DRIVER INTERFACE

Group Leader Simen Tufte

Pedal Box

Cedrick Syvertsen

Steering System

Eirik Olsen Tjøstheim

Ergonomics

Gjermund Ø. Pedersen

CONTROL SYSTEMS

Group Leader

Torque Vectoring

Modelling & Simulation

Eskil Mogstad

Andreas Rodahl

Adam Kosinski

Viljar Femoen 51

Adaptive Dampers

Marius von Hafenbrädl

SOFTWARE DEVELOPMENT

Group Leader

Miakel Steenbuch

Software Engineer

Juni Sæther Skarpaas

Software Engineer Inge Grelland

AUTONOMOUS SYSTEMS

Group Leader

Autonomous Engineer

Detection Engineer

Autonomous Engineer

Gina Fasseland

Haakon Paaske

Aksel Næsby

Lars Breirem 52

Brage Imset

Sindre Havn

DRIVERS

Driver Coach Kaja Erfjord

Driver

Mia Elisenberg

Driver

Asbjørn Verlo

Driver

Endre Stedje

Driver

Jostein Brovold

embotech 54