Research on the Nonlinear Computer Torque control of the MR Damper Based Above-knee Prosthesis

Abstract

Aiming at the motion track controlling of the semi-active magnetorheological damper based above-knee prosthesis (MRAKP), according to the LaSalle’s invariant set theorem, a kind of nonlinear compute torque (NCT) control law for the track controlling of the AKMR, is proposed to promote the robustness and performance of the intelligent above-knee prosthesis. The proposed NCT controller includes the feedforward control and the feedback control. The former one is used to compensate the nonlinear terms in the dynamic model of the MRAKP, such as the Coriolis force, the centripetal force, and the gravity. The feedback control, utilizing a nonlinear PD controller, adaptively adjusts the control gain coefficients and reduces the system error. On these bases, numerical simulations on the MRAKPare carried out to analyze the performance of the proposed NCT controller in ADAMS and simulink. For comparing, the track controlling performance of the PD controller and the CT+PD controller are also presented in the paper. Simulation results indicate that the proposed NCT controller for the MRAKP is able to adaptively adjust the control gain coefficients with lower track error and higher robustness than the conventional PD controller and the CT+PD controller.