A manual wheelchair assistance system which cancels a gravitational force on a slope

This paper proposes a novel driving assistance system for a manual wheelchair. On an inclination road, there is a high risk of moving the direction, which a manual wheelchair user does not intend, because of a gravitational force. Our proposed system cancels the wheel traction, which is generated according to the inclination of the road, using only servo brakes on each wheel. Our system measures the inclination of the road and estimates the wheel traction generated by a gravitational force. Then, our system cancels this traction and its user can use this wheelchair as its user drives it on no inclination flat ground. Its user can use it intuitively because its user drives this wheelchair by rowing its hand rims as usual and our assistance system works passively with their own intentional force. For realizing this idea, our system uses only servo brakes which can generate the various required brake traction. Our system does not require actuators, and its mechanism is simple and low cost. There is no risk by malfunction of servomotors. We test our proposed assistance system by the experiments with our prototype and verify its effectiveness.