Robust control algorithms for a hydraulic actuator with variable displacement vane pump

In this paper a robust tracking controller is designed for a hydraulic actuator controlled by a variable displacement vane pump. The nonlinear model of the actuator is linearized around equilibrium points and a robust tracking controller is designed for the linear model covering step and ramp reference and disturbance signals. The proposed robust controller is applied to the nonlinear model. The robust stability of the closed loop linear model and the local stability of the nonlinear model are guaranteed under sufficient conditions. The robust controller is derived using a finite step algorithm based on a Hurwitz invariability technique. Simulation results for various uncertain model parameters are presented indicating the satisfactory performance of the robust controller for the nonlinear model of the hydraulic actuator.