Two-legged stair-climbing wheelchair and its stair dimension measurement using distance sensors

This paper presents a stair-climbing wheelchair mechanism and its stair dimension measurement method using distance sensors. The wheelchair climbs stairs using two legs having 7 degrees of freedom. The size of the proposed wheelchair is equal to or smaller than that of other commercially available wheelchairs. The proposed wheelchair can climb steep stairs (more than 30° slope), while the seat trajectory is smoothly controlled. Distance sensors are used for measuring the heights and widths of the stairs and the wheelchair direction error. Experiments were performed to test the stair-climbing mechanism and the sensing algorithm for the stair feature estimation.