In view of the characteristics of parameter perturbation and uncertainty for drive system of hydraulic press,the mathematical model of drive system was established and a hybrid multi level robust control scheme that employed inner loop pressure tracking and outer loop velocity control was proposed.The outer loop velocity output tracking controller and prefilter were designed by using the Quantitative Feedback Theory.In the inner loop level,a nonlinear disturbance observer based upon radial basic function neural network was developed to track desired pressure with system uncertainties.Also,the ability of disturbance rejection for the disturbance observer was proved based on Lyapunov stability theorem.Simulation results show that the presented control strategy can improve the dynamic performance of the driven system and restrain the system uncer tainty evidently.Furthermore,the proposed approach is able to realize the smoothness with strong robust stability during the velocity switching transient period effectively.
