Robust Impedance Control of a Lower-Limb Rehabilitation Robot Using Fuzzy Parameters

This paper presents a novel design for the robust impedance control of a lower-limb rehabilitation robot by using fuzzy parameters and voltage control strategy. Selecting the impedance parameters has been a challenging problem, thus they are given by fuzzy systems in the proposed design. Compared with the previous designs, the novel impedance control approach is not dependent on the mechanical model of robot. Designing the controller is based on the voltage control strategy which differs from the common torque control strategy. Compared with the designs based on the torque control strategy, it is simpler, less computational and more effective. In addition, the controller considers the actuators. The proposed approach is robust adaptive against uncertainties by using a gradient decent algorithm. The stability of control system is proven and the efficiency and superiority of the robust impedance control with fuzzy parameters over the robust impedance control with constant parameters are shown by simulation results.