Synchronized control of multiple electrohydraulic systems with terminal sliding mode observer under parametric uncertainty and external load.

The leader-following synchronization control strategy is proposed for multiple electro-hydraulic systems (MEHS) to realize all the follower outputs of electrohydraulic systems synchronized to a virtual leader demand. Due to existed lumped uncertainties generated by some uncertain errors of hydraulic parameters and unascertainable external load disturbance, the synchronization control performance of MEHS will be degraded by using many common controllers. In this study, a terminal sliding mode observer (TSMO) is adopted in the MEHS to estimate the lumped uncertainties such that guarantees uncertainty estimated errors convergence to zero in a finite time. Then a synchronized controller of MEHS is designed by backstepping iteration and Lyapunov technique to guarantee the output cylinder position of every EHS tracking the virtual leader demand. Finally, the feasibility and effectiveness of the designed TSMO and the proposed synchronized control strategy are verified via simulation and experiment.