Power steering and force display controls for a cycling wheelchair using servo brakes

In this study, we present a new type of wheelchair called the cycling wheelchair, in which the user moves the wheelchair by pedaling with his/her legs and changes direction using a steering handle. This wheelchair has great potential not only as an effective rehabilitation device but also as a mobility assistive device. However, the commercially available model has several hardware limitations that affect the steering operation. In this paper, we discuss these hardware limitations before presenting methods for improving steering maneuverability. Furthermore, we propose power steering and force display controls based on environmental information. From the perspective of safety, we employ servo brakes to control the cycling wheelchair, and the assistive functions are realized based on the feasible braking control region. The proposed control methods are experimentally applied to a newly developed cycling wheelchair with servo brakes, and the results illustrate the validity of the control methods.