Position control of a hydraulic servo system using sliding mode with discontinuous surface

In this paper, we present a method to control the position of a hydraulic servo system rod. Our approach of control consists in using sliding mode control. First, we use a linear virtual controller using the classical sliding mode control. This controller ensures the sliding mode but do not achieve the reference output. To overcome this problem, we propose to design a sliding surface using backstepping method and variable structure controller to achieve discontinuous surface. This approach guarantees a robustness against perturbation and uncertainty. Next, we design a sliding mode observer to estimate the states of the system using only the rod position. We show that the controller issued from the estimated states also lead to reference position tracking. The efficiency of this approach is illustrated by numerical simulations.