High-Gain-Observer-Based Integral Sliding Mode Control for Position Tracking of Electrohydraulic Servo Systems

Although previous control methods improve control performance in electrohydraulic servo system (EHSS), they require full-state feedback information and/or the derivative of the measured signals so that noise may be amplified. In this paper, we propose a high-gain-observer-based integral sliding mode control to improve the position tracking performance of the EHSSs while solving the previous problems. The proposed method consists of a high-gain observer and an integral sliding mode controller. The high-gain observer is designed to estimate the velocity and load pressure using the position feedback. The stability is proven without the approximation of the model in EHSS. The integral sliding mode controller is proposed to improve the position tracking performance using the flatness property of the system. In the controller, the required derivatives of the state variables are obtained using the flatness property without employing the derivative of the measured signal.