Omni-Directional Mobile Wheelchair Capable of Ascending Stairs Using Only Wheels

We have developed an omni-directional mobile wheelchair that can ascend stairs using only wheels even if the stairs have different dimensions. Omni-directional movement reduces the burden of moving in tight spaces and enables intuitive operation. However, stair climbing is still an issue for powered wheelchairs in general. In this research, we focus on a dual-wheel active-caster mechanism that has a simple structure and can move in all directions using normal tires, and examine stair ascending. We investigate the conditions required for ascending stairs and show that it is possible to ascend stairs by making the wheelbase variable and installing a center of gravity movement mechanism. We verify the effectiveness of the proposed mechanism through experiments using a 1/2 scale experimental machine and simulations using MATLAB/Simulink and Simscape. The results showed that ascending stairs can be achieved by changing the wheelbase to match the stair dimensions and equalizing wheel loads during ascending stairs.