Bidirectional synchronization control for an electrohydraulic servo loading system

Synchronism is one of the most important factors for electrohydraulic servo loading systems with multi-axis. As electrohydraulic servo loading systems have a large output force/torque, the coupling between each axis can cause great nonlinearities and uncertainties, which seriously deteriorates the performance of the systems. In this paper, an electrohydraulic servo loading system is used for studying its bidirectional synchronization control. The mechanism of the coupling between two cylinders from two directions is discussed and the experiment results of coupling are obtained. A bidirectional synchronization iterative learning control (BSILC) method is designed to improve the tracking performance, robustness and compensate the synchronization error. The simulation and the experiment have been conducted. The results indicate that the control strategy proposed in this paper is valid. The tracking performance, robustness and synchronism of the electrohydraulic servo loading system have been remarkably improved.