PLC based variable structure control of hydraulic position servo system considering controller saturation

摘要

Due to the advantages of strong carrying capacity and fast response speed, hydraulic servo system has been widely used in industrial motion control field. The hydraulic servo system is susceptible to the nonlinearity, parameter uncertainty and unknown disturbance, which makes the high performance position control of the hydraulic servo system become a challenge. In this paper, considering the hydraulic position servo control system with input saturation, a sliding mode variable structure controller with shrinking boundary layer is designed. The proposed method is used to experimentally track three kinds of reference signals based on Programmable Logic Controller (PLC), i.e., S7-200PLC, and hydraulic control system provided by Festo company. The experiment results indicate that the proposed method is effective and achieves smaller steady state tracking error as compared with sign function robust item and the conventional PID control.