Symmetrical compensation control of asymmetric hydraulic system based on output feedback

The current asymmetric hydraulic systems generally have the issues, like tedious algorithm of control methods due to inconsistent positive and negative characteristics, high tuning workload of controller and poor reliability of control system. So in this paper, a symmetric control method for asymmetric hydraulic system based on output feedback is presented. In this method, the asymmetric hydraulic system is transformed into a state space symmetric system through dynamic compensation control based on output feedback for asymmetric hydraulic system, then unified PID control is applied for positive and negative directions of symmetric system after transformation. And then the general algorithm from asymmetric system to symmetric system is given to adapt to all unchanged systems of the asymmetric linear. Finally, this method is applied to the valve controlled symmetrical hydraulic cylinder. Through matlab simulation and experiment, it is proved that the control method of the transformed system has been simplified, and the stability and dynamic characteristics of the system have been improved to some extent, and eliminate the oscillation of the system. This study lays a foundation for the application of symmetric control theory in asymmetric systems, and is of great help to the realization of high precision position tracking control for hydraulic servo systems. © 2018, SHPMedia Sdn Bhd. All rights reserved.