An assistive wheelchair based on a concept of a passive robotics

We propose a novel assistive wheelchair based on a concept of a passive robotics. Our proposed wheelchair consists of a frame, casters, wheels and servo brakes. Our wheelchair system estimates the trajectory its user wants to go using the characteristic of the rowing motion and realizes the estimated tracks by controlling a torque of the servo brake. Our system requires no actuators, and its mechanism is simple and low cost. There is no risk by malfunction of servomotors and patients can use it intuitively because they use our wheelchair passively with their own intentional force. Our key ideas are two topics. One is the development of novel passive-type assistive wheelchair which is suitable for a practical use. The other key topic is a novel driving assistance algorithm with estimation of the user´s intention. For realizing this estimation, we use the minimum jerk trajectory model, which expresses a typical human movement. Our proposed system compares a beginning part of rowing motion by the user and this trajectory model, and estimates the whole rowing motion which will be performed. Using our proposed system, the user can drive our wheelchair with natural feeling. We test our proposed assistance system by the experiments with our prototype and verify its effectiveness.