Grey prediction based adaptive sliding mode control for electro-hydraulic actuator system

In this study, an adaptive sliding mode controller with PID tuning method based on the grey predictor (SMCGP) is proposed to control an EHA system. The simple test rig using the EHA and MR fluid damper was setup for the investigation. In the SMCGP, the PID controller is employed to approximate the sliding-mode equivalent control along the direction that makes the sliding-mode asymptotically stable. Due to the system nonlinearity of the EHA system the PID control gain parameters are computed according to the adaptive law. Furthermore, the fuzzy grey predictor (FGP) takes part in estimating the system output in the near future to optimize the controller parameters in advance. The proposed controller was evaluated with the conventional PID controller in controlling the damping force of the EHA system with respect to the different desired force and supply current levels applied to the MR damper. Experimental results are carried out to investigate the effectiveness of the proposed controller.