Development of an assistive wheelchair caster unit for step climbing — Design and construction of a unit

The purpose of this research is to develop a mechanism which assists the wheelchair user to climb a step. We design the wheelchair caster unit which has a assistive mechanism. This unit is easily replaced with a conventional wheelchair caster, thus it has an advantage for general use. In order to assist the wheelchair user to climb a step, the caster unit has two functions. One is the assistive plates to enlarge the caster radius imaginarily. The other is a lock function of caster rotation for yaw direction, which enables easy step climbing with oblique approach. In particular, this paper proposes the system configuration of the unit. First, we discuss the required functions for assistive plates and the lock function. Next, we verified the efficiency of above functions by using simulation. For the simulation results, following things are confirmed. The assistive plates reduce the driving force of wheelchair user in case of step climbing. The lock function can assist the driving force when the wheelchair climbs a step with oblique approach. Last, we made a detailed design and constructed the actual caster units.