Novel regenerative braking control of electric power assisted wheelchair for optimal velocity driving on downhill road

This paper describes a novel regenerative braking control scheme of electric power assisted wheelchairs for optimal velocity driving on downhill roads. "Electric power assisted wheelchair" which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, it has no braking system to suppress the wheelchair's velocity and brings the dangerous and fearful driving especially on downhill roads. Therefore this paper proposes a novel safety and efficient driving control scheme based on the regenerative braking system. This study applies the regenerative braking system with the step-up chopper circuit serially connecting two motors and realizes the velocity feedback control with the variable duty ratio so that it tracks the optimal velocity based on minimum jerk model. In addition, the dynamic braking system is also applied at the low speed range instead of the regenerative brake in order to suppress the acceleration. Some driving experiments on the practical downhill roads show the effectiveness of the proposed control system.