Robust Performance Control For AC Servo System

Almost everyone of physical systems due to various reason of the inner part and exterior, which is still influenced by the plant parameter variations and external disturbances. Because these uncertainties existence, in fact, optimum control which obtained according to the ideal model not only can't guarantee optimum, but also cause the control quality to descend seriously. In this paper, Aim at the influence of parameter variations and external disturbances to the high speed and high accuracy systems, robust control theoretical method is adopted, two kinds of control strategies were put forward, in order to resolve the problem above-mentioned.First is the study of robust controller according to the foundation of control theories, when the parameter perturbation occurred in the plant, state feedback controller which Cause the system quadratic stabilization is need to be designed. In this paper, the design problem of quadratic stable controller is changed into H_∞ standard design problem based on state feedback. Then on the base of H_∞ standard design, robust progressive stabilization condition of the system is given with the LMI form, the feedback controller is obtained by feasible solution of LMI. When the system is influenced by the parameter variations and external disturbances, the controller make system stable. The feasible solution can be obtained through the LMI tool box.An H_∞ adaptive controller with a pre-specified H_∞ property is proposed for the tracking control of permanent magnet synchronous motors, introduction of a feed-forward compensation and a parameter tuner to reduce the influence of uncertainties and external disturbances. In face of uncertainties and external disturbances, once H_∞ property is satisfied, the capability to track input is achieved, the robust performance control problem is formulated as a nonlinear H_∞ problem. In order to solve a problem of nonlinear H_∞, a parameter tuner and a H_∞ feed-backward controller and compensation control is integrated, the synthesis is achieved bychoosing a quadratic storage function. The result to track step command are provided demonstrate the effectiveness of the proposed adaptive Hm controller.In this paper, Riccati inequality is changed into LMI according to schur complement theorem, the solution of controller is obtained through LMI, and the process to solve is simplified. Simulation results are given to demonstrate the effectiveness of the proposed control scheme, which have not only good robustness but also Quick-response.