Backstepping sliding mode control for electro-hydraulic servo system with input saturation via an extended state observer

The position tracking control scheme is investigated in this paper for electro-hydraulic servo system with parameter uncertainties and external disturbances. First, the total uncertainty is estimated via an extended state observer, and backstepping sliding mode control law based on the extended state is designed to ensure the system output track the reference signal. Then the control strategy for electro-hydraulic servo system subjected to input saturation is further considered. The extended state observer technique is applied to compensate the effects of the compound uncertainty, which contains not only the parameter uncertainties and external disturbances, but also the unknown input saturation. With the proposed method, the stability of the resulting closed-loop system is proven and the tracking errors converge to a small neighborhood of zero. Finally, simulation results are presented to verify the effectiveness of the proposed tracking control strategies. © 2014 Binary Information Press.