Modeling and Position Tracking Control of a Novel Circular Hydraulic Actuator With Uncertain Parameters

Abstract

In order to realize precise position tracking of a novel circular hydraulic actuator with parameter uncertainties and bounded disturbances, an adaptive sliding mode controller (ASMC) that incorporates a fuzzy tuning technique is proposed in this paper. The mechanical structure and basic principle of the actuator are first introduced, and the mathematical model of its corresponding valve-controlled hydraulic servo system is constructed. Based on Lyapunov stability theory, online parameter estimation and sliding mode controller design are effectively integrated to approximate the equivalent control of sliding mode. To mitigate the undesired chattering phenomenon and further improve system performance, a fuzzy tuning scheme is employed to regulate the proportional gain of the approaching control term. In addition, a real-time control platform is established, and the controllers parameter identification and position tracking are verified by preliminary experiments. Finally, the traditional PID controller and the exponent approaching sliding controller are also conduced to further evaluate the control performances of the designed controller, and the comparative results demonstrate that the proposed control scheme has better control performance in reducing errors for trajectory tracking.

Keywords

• Position tracking
• circular hydraulic actuator
• parameter uncertainties
• adaptive sliding mode control
• fuzzy tuning scheme