Robust Position Control of an Electro-Hydraulic Servo Motor System with Friction Compensation

抄録

Hydraulic motor systems are widely used in a variety of applications, including power control systems of wind turbines, construction equipment, automotive systems, aerospace components, etc., because they have advantages such as a high power-to-weight ratio, high stiffness, and quick response. However, hydraulic motor systems are known to be highly nonlinear and challenging for modeling because of valve characteristics and friction in the hydraulic motor. Therefore, precise tracking control of the motor's rotation position is often a difficult task. In this study, a multi-sliding mode control method combined with a friction observer is proposed for precise control of the rotation angle position of a hydraulic motor. The multi-sliding mode controller is applied to address the nonlinear characteristics of the system, while the friction observer is used to compensate for the friction torque in the hydraulic motor. First, an electro-hydraulic servo motor system is proposed, and the mathematical model of the system is then constructed. Next, the multi-sliding mode controller and the friction observer are synthesized. The LuGre dynamic friction model is used in the design of the friction observer. The system stability is then analyzed based on the Lyapunov stability criterion. Finally, the angle position tracking of the motor is validated by simulations, and the results indicate the effectiveness of the proposed controller compared to conventional multi-sliding mode controller and PID controller.