Discrete Sliding Mode Control for a Non-minimum Phase Electro-hydraulic Actuator System

The main objective of this paper is to perform a robust controller design using discrete-time sliding mode control (DSMC). In the control scheme, two-degree-of-freedom (2-DOF) control strategy turns the DSMC, which generally utilized state feedback into output feedback controller. The designed control scheme is considered with feedback and feedforward combination by implementing the zero phase error tracking control (ZPETC), which particularly intended for the nonminimum phase electro-hydraulic actuator (EHA) system application. In the experimental works, a sinusoidal trajectory with different frequencies is employed to assess the DSMC performance under nonlinear and uncertain condition. Experimental results show the DMSC with perfect tracking control approach is capable to reduce the phase lag occurred due to nonlinear phenomenon. The proposed controller also is highly robust under various points of trajectories and significantly shows enhancement in tracking control performance as compared to the conventional controllers.