Abstract
A wheelchair with an assistive power unit employing a differential gear is now under development. The wheelchair is specially aimed to those who have a little residual power to drive a hand driven wheelchair, but often use a powered wheelchair. People who have C5 or C6 level spinal cord injury or the aged who have lower limb impairment are initially considered. The purpose is to encourage them to keep their residual ability or even to improve it by adjusting the assistive ower. A prototype has been developed and tested on experimental basis. The prototype has one DC servo motor(120W)and the output torque is transmitted to rear wheels through a differential gear, Oldam's shaft couplings and electromagnetic clutches. Applying voltage to the clutches turns the land-driven wheelchair into a powered wheelchair. The control system is utilizing an 8 bit single chip microcomputer and rotation angle sensors. Velocity feedback control is installed in the oftware. In addition to performance tests following the JIS test procedures, 11subjects, hand-driven wheelchair users tried the prototype and found its operation easy and that it is helpful when ascending or descending a slope.
