Position Control of an Electrohydraulic Servo System Based on Sliding Mode Adaptive Fuzzy Controller

Electro-hydraulic servo systems are one of the most important control systems used in many fields such as industrial automation, numerical control machines, the oil and gas industry. Due to the non-linear behavior of hydraulic system components and the presence of various uncertainties in their operation, the modeling and control of these systems face problems. In this paper, a fuzzy adaptive controller based on sliding mode control is proposed to control the position of an electrohydraulic servo system and overcome the uncertainties. The proposed robust controller results in minimal dependence on the system model. The system's stability in the presence of uncertainties has been proved by applying the Lyapunov theory and considering the time-varying nature of the uncertainties. Besides, to approximate the maximum band and the range of uncertainties, an adaptation law has been proposed for its estimation. The simulation results show the reasonable and stable performance of the proposed adaptive fuzzy controller compared to other control methods.