Constantin Wiesener

The Cybathlon RehaBike: Inertial-Sensor-Driven Functional Electrical Stimulation Cycling by Team Hasomed

Our Team Hasomed joined the functional electrical stimulation (FES) bike race at the very first Cybathlon, which was organized by the Swiss Federal Institute of Technology in Z?rich (ETH Z?rich). This article describes our technical approach regarding the tricycle, the stimulator, and the inertial-sensor-based control strategy used for training and during the race. Due to the cycling devices independence, the same setting and stimulation pattern can be used for either regular or ergometer-based cycling. Regarding the bike architecture, the focus was on using standard components as much as possible and enabling an easy and autonomous transfer between the wheelchair and the tricycle. Together with our paraplegic pilot [spinal cord injury (SCI) lesion level T5/6, American Spinal Injury Association (ASIA) Impairment Scale Grade A], we developed a training plan and an electrode setting that was continuously improved upon over the course of 18 months. Right before the Cybathlon, our pilot was able to cycle the full race distance of 750 m five times with 5-min rests in between in a gymnasium. At the Cybathlon, our athlete completed the 750-m race, taking fourth place with a new personal record of 6 min and 44 s. With our work, we showed that an inertial-sensor-based joint-angle estimation can be used for smooth and effective FES cycling.

Control of an extracorporeal heart assist device

Heart assist devices provide mechanical circulatory support for patients with end-stage heart failure. Extracorporeal blood pumps are applied to adult and pediatric patients in the case of uni- and biventricular assistance. Modern driving units provide more mobility what is an immense benefit to the quality of life of the patients. The treated heart assist device in this article is the EXCOR system (Berlin Heart GmbH, Germany), which is a pneumatically driven extracorporeal assist device. It allows uni- and biventricular heart support. The automatic control system should match the pump output to the metabolic needs by controlling the piston movement and the enclosed air mass in the pneumatic system. This paper describes the design of a control system for the extracorporeal assist device. A developed model is used for controller synthesis. This model is based on modified basic physical equations and optimized for practical applications.