Design Of The Two-Degree-Of-Freedom Robust Controller For Motion Servo System

Design of controller, dealing with uncertainties existing in motion servo systems is discussed in this thesis. A two-degree-of-freedom (2-DOF) robust controller design method is studied in the framework of H_infinity control theory. The 2-DOF robust controller is obtained, and the simulation result validates the method proposed.Firstly, the scheme of the simulation turntable is introduced. The plant model is derived based on the first-principle model of the brushless direct current motor (BDCM). The main possible uncertainties of the system, which impact on the performance of the close loop, are analyzed and described.Secondly, a 2 step design procedure is determined considering the features of the 2-DOF method. The specific control problems of the feedback and feedforward controller design are discussed. And the performance requirements are assigned respectively.Thirdly, the procedure for the robust feedback controller design is introduced using the robust control theory and the constructive singular value theory. A sufficient condition for guaranteed improvement in output-tracking performance with the use of the feedforward is discussed. Then the procedure for the robust feedforward controller is derived based on the framework of H_infinity control theory. The method of the feedback and feedforward controllers'parameterization is given.Finally, the above theoretical results are applied to a practical electronic simulation turntable. The simulation results show the effectiveness and feasibility of these methods.