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Mathematical Problems in Engineering
Volume 2015, Article ID 890704, 9 pages
Research Article

Variable Structure Compensation PID Control of Asymmetrical Hydraulic Cylinder Trajectory Tracking

School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China

Received 14 July 2014; Revised 5 October 2014; Accepted 15 October 2014

Academic Editor: Yuqiang Wu

Copyright © 2015 Difei Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A novel variable structure compensation PID control, VSCPID in short, is proposed for trajectory tracking of asymmetrical hydraulic cylinder systems. This new control method improves the system robustness by adding a variable structure compensation term to the conventional PID control. The variable structure term is designed according to sliding mode control method and therefore could compensate the disturbance and uncertainty. Meanwhile, the proposed control method avoids the requirements for exact knowledge of the systems associated with equivalent control value in SMC that means the controller is simple and easy to design. The stability analysis of this approach is conducted with Lyapunov function, and the global stability condition applied to choose control parameters is provided. Simulation results show the VSCPID control can achieve good tracking performances and high robustness compared with the other control methods under the uncertainties and varying load conditions.