Robust Switching Control of the Direct-Drive Servo Control Systems Based on Disturbance Observer for Switching Gain Reduction

Due to the existence of external disturbance which affects the systems' robustness and stability, a robust sliding mode switching controller with disturbance observer method has been developed for the switching systems of the direct-drive servo control systems, which can eliminate the chatter and reduce the switching gain of the switching systems completely or alleviate it greatly. According to the Lyapunov stability method and the periodically switching law, the resulting closed-loop switched system is robustly stable such that all the signals in the resulting closed-loop switched system of the direct-drive servo control systems keep bounded and the sliding surface of the switching system can be well reached. Finally, the presented switching control scheme is easy to implement and simulation results illustrate the good control performance.

I. Introduction

The Direct-Drive Valve systems are one of the main components which affect the system output performance of the aerospace servo system significantly, which have wide applications in many control fields [1]–[4]. An electrical servo motor of direct drive valve (DDV) is employed to eliminate the disadvantages of the system high sensitivity to oil-contamination and complicated structure, which provides good control output performance. Thus, a host of advanced control strategies have been captured more attention in recent years. As we know, the PID control schemes are by far the most widely employed in industrial control applications, due to its popularity stems from its easy operation, simple system structure and applicability in a wide variety of operating [5], [6], [14], [21], [22]. When the system exists complex, time-varying and some large disturbances, traditional PID control scheme cannot realize the consistent control performance [5], [6].