Asymptotic output tracking control of electro‐hydraulic systems with unmatched disturbances

Abstract

In this study, an introduced auxiliary error signal‐based robust control method and an adaptive control strategy are synthesised through backstepping method for high precise motion tracking control of double‐rod hydraulic servo systems. The controller takes the non‐linear behaviour in flow, unmatched disturbances in inertia load dynamics, and matched uncertainties in pressure dynamics into consideration. In addition, the developed controller does not require a priori knowledge on the bounds of the lumped disturbances and the gain of the devised robust control law can be tuned itself. As a result, the obtained control strategy can achieve an exact tracking performance for the whole closed‐loop hydraulic system in the presence of matched and unmatched uncertainties simultaneously. Extensive experiments are carried out for the trajectory tracking control of a double‐rod hydraulic servo system and the results reveal the high‐performance of the presented controller.