High-tech wheelchair with FAULHABER motors

Silvia Rohner as team leader of the MedTech Lab and the Enhanced Teams combine know-how and a developer spirit in the interests of accessibility. They draw on years of experience, work in an interdisciplinary manner and have great vision. This is the case with “ZED evolution”, the wheelchair 4.0. The idea for this was born in 2015 - a long period of tinkering and testing was carried out to develop a robust vehicle that can easily overcome obstacles in everyday life. They worked together with a patient, paraplegic Florian Schoch. He was also the one who successfully maneuvered the robotic wheelchair through the course at the first Cybathlon and won the Wheelchair Race.

During a visit to the OST University of Applied Sciences, the scientists and engineers provide an insight behind the scenes and into the project procedures. Based on the problem at hand, Silvia Rohner's team always works in close collaboration with those affected and various groups. These can be paraplegics, orthopaedic technicians or relatives of those affected. She describes how the projects are developed and collaborated on: “We first try to clarify: ‘What is the actual problem?’ What problems arise in everyday life that we can then [...] tackle? In the next phase, we develop ideas on how we could solve this technically. [...] And then we go back to the users [...] and ask: “Hey, is that a good idea?”

Modifications are then made based on this exchange and the findings. An iterative process that reveals possibilities and demands a wealth of ideas. There is no such thing as a typical working day, as every day is different and is usually roughly planned in the morning. The team's TechLead, Benjamin Eggimann, explains how the team members work: “First, maybe a bit on the computer, then we go to the hardware and try to make sure it works properly. And then we start testing that we really have a good device that works so that we can also put people in it."

A total of seven FAULHABER motors are installed in the wheelchair for functionality and maneuverability. A DC micromotors from the 3890...CR series is located in the seat adjustment, for example. This allows the seat to be moved effortlessly forwards and backwards in order to adopt different positions or shift the center of gravity as required. When the seat is at the front, the user can comfortably approach a table. When the seat is in the rear position, the legs can be stretched out at the top for longer, level journeys. The wheels are also driven by powerful FAULHABER motors. Brushless flat motors from the BXT series allow the wheelchair to move off in all directions and maneuver in the smallest of spaces.

Benjamin Eggimann summarizes how the drives have to be designed: “As small as possible, as power-dense as possible, because you really push them to the limits.” While components, functions and features are discussed in the laboratory, the reality check takes place on the in-house test track. Is it easy to negotiate the bumps? Can you manage the stairs? Does the robot arm operate the door handles without any problems? Feedback from the user is essential during these test runs, as they can tell directly whether everything is working or needs to be readjusted.

Once the practical test has been passed, nothing stands in the way of everyday use or competition. Successful implementation and results generate enthusiasm and pride among the entire team. And this also reinforces their hopes for the upcoming Cybathlon: “Of course, we want to be among the front runners again. We are currently the defending champions [...], so expectations are high!” says Benjamin Eggimann.