An assistive wheelchair caster unit for step climbing

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 the conventional wheelchair caster, thus it has a advantage for general use. In order to assist the wheelchair users 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 climbing a step with oblique approach. In this paper, first, we discuss the required functions which are 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 users in case of climbing a step. The lock function can assist the driving force when the wheelchair climbs a step in case of oblique approach. Last, we constructed the actual caster unit and evaluated it by conducting some experiments. From the experimental results, it is turned out that proposed caster unit enables to ease step-climbing including oblique angle.