H∞ Robust Adaptive Control for High-Precision and Micro-Feed Permanent Magnet Linear Synchronous Servo System

In the high-precision macro-feed machine processes, a rapid, sensitive, high-speed and lightweight system is required. Permanent magnet linear synchronous motor (PMLSM) becomes the best acting mechanism by removing the middle mechanical driving chains. But various disturbances such as variation in load directly act on the servo motor without any buffering. So performance index of system is decreased and which even leads to the instability of system. The system is expected to design the robust controller on line to remove the influences of inner parameter perturbation and external disturbance. In this paper, the H _infinrobust control law has been combined with the robust parameters estimator. The global stability can be guaranteed and the disturbances are suppressed when parameter uncertainties, bounded disturbance and unmodelled dynamics are existed. H_infin robust adaptive control is proposed to overcome the influences to the system caused by the uncertain factors such as external disturbance and model error and so on, to improve the performance and guarantee the robust stabilization of the system automatically. The demands on precise control for PMLSM with multifold uncertainties are satisfied in the proposed scheme. The simulation results indicate the proposed method has strong robustness and the control effects are excellent