Power-assisted wheelchair with gravity compensation

To overcome disadvantages of conventional manual or motorized wheelchairs, the push-rim activated power assisted wheelchair (PAPAW) has been developed. Though with the help of PAPAW the rider can climb slopes without much exertion, PAPAW cannot be finely position-controlled on the slopes, and the rider´s hands are not free while pausing on the slopes. In order to solve these problems, the gravitation-compensating power-assisted wheelchair (GCPAW) is suggested in this paper. When the wheelchair is manually moved, the wheel and the driving mechanism (motor and reduction gears) should be disconnected to avoid generating a friction force. For this purpose, an electromagnetic clutch is used in the driving mechanism. In addition, friction compensation during the power-assistive mode is suggested. As a preliminary work, experiments for gravity and friction compensation were performed. The rider could feel like riding an ordinary manual wheelchair on the flatland, even on slopes.