Maneuverability Improvement of Front-Drive-Type Electric Wheelchair STAVi

Electric-powered wheelchairs have been used as a convenient transport device for the elderly and disabled. The riding capability of a wheelchair is one of the most important functionality for wheelchair users. Therefore, the authors developed a new front-drive-type electric wheelchair “STAVi” to achieve a comfortable ride for wheelchair users. It is easy for a disabled person to climb into this wheelchair from a bed because they can do so by piggybacking from a bed or chair. Moreover, the base plane of STAVi is very low compared with traditional rear-drive-type wheelchairs because the motors and all electric devices are placed in the front. Such functions are very useful not only for the disabled but also for care personnel, because the riding task is very difficult with rear-drive-type wheelchairs. However, front-drive-type wheelchairs are hard to run straight and difficult to operate because their sensitivity to disturbances is higher than that of rear-drive-type wheelchairs. In particular, the dynamics on a slope are complex to allow for easy driving because the gravitational force acts as a disturbance. This paper analyzes the dynamics of front-drive-type wheelchairs and propose a wheelchair control method that compensates for the difference between the dynamics of the actual wheelchair and that of a desired wheelchair model by using yaw rate and velocity feedback. It is expected that the user can easily operate STAVi on a slope easily via appropriate compensation. The effectiveness of the proposed method is confirmed by driving simulations and experiments.