Society today is more mobile than ever. People use cars, bicycles, trains, and airplanes to travel without thinking about the challenges that exist for those with physical disabilities. For them, basic mobility needs pose obstacles in everyday life that can be insurmountable. Expensive installations such as ramps, elevators, and chairlifts have been used to attempt to solve these problems, but wheelchair users say these approaches can be slow and make them feel quite exposed. Our team wanted to make a difference.
The Scalevo Team
The Scalevo team combines many different talents, including eight students from the Swiss Federal Institute of Technology (ETH) in Zurich (seven mechanical engineering students and one electrical engineering student) and two design students from the Zurich University of Arts (ZHdK). The Autonomous Systems Lab (ASL) supervises the project.
ETH Zurich Students: Carlos Gomes, Roman Käslin, Jonas Kühne, Dario Mariani, Milan Schilling, Ian Stähli, Miro Voellmy, Bernhard Winter
ZHdK Students: Thomas Gemperle, Naomi Stieger
Faculty Advisers: Péter Fankhauser, Lehmann Daniel, Lennon Rodgers
The ETH Zurich students could participate in Project Scalevo as part of a yearly focus project. Students use these year-long projects to acquire more practical experience than can be gained during the course of a lecture.
An Ambitious Goal
As mentioned, we had just one year to build a functional prototype. An electric wheelchair is a complex and sizable vehicle, so we needed to manage all tasks very efficiently.
After completing the mechanical tasks, we needed to choose a programming language that could help us write code in the most time efficient and understandable way. After researching many different options, we decided LabVIEW would be the best choice for our project. The graphical interface helped the mechanical engineers, many of whom had little programming experience, get accustomed to the language. It also empowered us to achieve feats that would not have been possible in the same time period with a different software environment.
A Multifunctional Device
Our wheelchair combines two well-known systems into one spectacular device. Rubber tracks offer optimal grip on difficult terrain, and sturdy wheels grant mobility and freedom on flat ground.
On stairs, the two tracks fold out to adjust to the angle of the stairs. The track material was specifically built for stairs and delivers excellent grip for safety. Once the wheelchair reaches the top of the stairs, two small wheels extend in the back to prevent the chair from falling over.
On flat ground, the wheelchair balances on two large wheels. These allow the chair to turn on the spot and move through tight spaces. The data measured by the IMU and the motor encoders is fed to the myRIO device. myRIO uses this information to control the inverted pendulum, which the wheelchair embodies, and allows the user to drive securely on only two wheels. Once the user reaches the destination, he can lower the tracks and the wheels to the floor and get off safely. We programmed this difficult transition phase with LabVIEW.
Why LabVIEW and myRIO?
From the beginning, we knew time was critical. Using LabVIEW, we could swiftly create programs for functions such as controlling the motors. The graphical interface helped everyone get accustomed to the language, so programming soon became a team activity. We could easily share functions and make changes. Furthermore, the highlight function improved debugging significantly, which saved even more time. Using shared variables facilitated the use of inputs received through the touch screen.
The myRIO device proved to be very useful because of its compact size. We could securely mount it to the frame of the wheelchair because of its casing. It also included all the necessary interfaces for the electronic components. Furthermore, its onboard WLAN was instrumental for early stage development, for example during the testing of smaller prototypes.
Using LabVIEW and myRIO, we created a wheelchair that can improve the lives of disabled people and give them the mobility everyone deserves. With these tools, we managed the control of a vast system and took a step into the future. We hope to accomplish even more in the next year.
ETH Zürich, Project Scalevo
Tel: +41 78 742 20 51