Exerted-torque estimation of a power-assisted wheelchair

A power-assisted wheelchair with user torque observer is presented in this work. The wheelchair wheels´ velocities are measured by the rotary encoders. The torque observer designed based on Lyapunov theorem is proposed to estimate the wheelchair wheels´ velocities. Based on the difference between the physical and estimated velocities, the user torque exerted on the push rims of wheelchair is estimated. Four-users torque-estimation experiments are illustrated with the wheelchair rests initially or moves, respectively. The experiment results indicate that the user exerted torques could be estimated correctly no matter wheelchair rests initially or moves. Therefore, using the proposed observer to estimate the user torques is feasible.