Zero phase two-degrees of freedom H∞ robust tracking control for permanent magnet linear synchronous motor

For the direct-drive servo system of permanent magnet linear synchronous motor (PMLSM), a two-degrees of freedom (2-DOF) robust tracking control strategy based on combining zero phase error tracking control (ZPETC) with H_∞ robust control is proposed in this paper. The control scheme solves the conflict between fast tracking performance and interference rejection of the linear servo system. The zero phase error tracking controller is designed to ensure that the system has fast tracking performance and implements exactly tracking, especially when it is used for contour control, better effect is obtained, it can effectively improve positioning accuracy and the fast tracking performance. While H_∞ robust controller can overcome the influences of uncertainties of the parameters perturbation and the external load disturbances, achieve the stability and robustness of the system. The simulation results show that the control scheme not only can enhance the fast tracking performance in the linear servo system, but also has the stronger robustness to parametric variations and resistance disturbances.