Research On Robust Tracking Control For Linear Motor Servo System

Taking the project supported by National Natural Science Foundation of China "Research on High Precision Micro-feed Servo System Driven Permanent-Magnet Linear AC Motor" as background, this dissertation researches the permanent magnet synchronous linear motor(PMLSM) servo feeding system used in modern advanced NC machine tool. For the characteristic of direct drive and the high requirements of robustness and tracking performance for servo system in NC machine tool, three control strategies are proposed to enhance servo performances of the system in this dissertation.For the disturbances including the specially existing end effect of PMLSM servo system, a disturbance observer is utilized in the velocity loop to eliminate and attenuate the influences of the factors. A PD controller is used in the position loop to construct an asymptotically stable system. A velocity and acceleration(V & A) feedforward controller is designed in the position for the sake of the motion control of high-speed response and high accuracy positioning and tracking performance.The periodic force disturbance is generated by specially existing end effect of PMLSM, which can not be rejected effectively by the disturbance observer. For that a repetitive controller is designed in the position loop to restrain the periodic disturbances. The performance of restraining disturbance is improved.Moreover, based on Pseudo Derivative Feedback with Feedforward Gain (PDFF) control configuration, H_∞mixed sensitivity control method was adopted, The controller is better in robustness against load disturbances and parameter variations. The controller raises the responding speed of the system to input signal, and solves the conflict between interference rejection and fast t racking performance.Currently available permanent magnet linear synchronous motor is considered as the controlled object, its mathematical model is established, and it is necessary to simulate and analyze above control strategies using MATLAB software, the simulations and experiments are conducted, which verify the feasibility of the theory studies and simulation results of the proposed control methods.