The effects of pressure variation in sliding mode controller with optimized PID sliding surface

The high demands in the control of force and position implemented in diverse applications have led to the increasing usage of Electro-Hydraulic Actuator (EHA) system. However, the EHA system is commonly exposed to the parameter variations, disturbances, and uncertainties, which are caused by the changes in the operating conditions. Hence, this paper attempts to analyses the impact of changes during the operating condition and a robust control strategy is then formulated based on the control law of the Sliding Mode Control (SMC), where the design of the sliding surface is integrated with the Proportional-Integral-Derivative (PID) controller. Then, the Particle Swarm Optimization (PSO) technique has been utilized to seek for the optimum PID sliding surface parameters. The findings indicate that the proposed robust SMC with PSO-PID sliding surface is preserved to ensure the actuator robust and stable under the variation of the system operating condition, which produce 26% improvement in terms of its robustness characteristic.