A study on a mechanism of a wheelchair caster unit for step climbing — Verification of required caster unit functions

The objective of this research is a development of the mechanism which assists the wheelchair user to climb a step. We designed the wheelchair caster unit which has a assistive mechanism. This unit is easily replaced with the conventional wheelchair caster. The proposed caster unit has two functions for assisting a step climbing. One is the assistive plates for enlarging radius of the caster imaginarily. The other is a lock-function of caster rotation for yaw axis, which enables easy climbing with oblique approach. This paper confirms the efficiency of these two 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.