The Study On Ultra Precision Position Servo System Based On Linear Motor

The ultra-precision feed system is one of the key components for ultra precision machining facility. But it is difficulty for conventional feed systems to achieve the submicron rank. Linear motor direct drive feed system cancel all intermediate transport segments, it greatly improve the working accuracy and servo performance of the machine tool, at the same time it adds the difficulties in the aspect of the electrical control.In this paper, the research object is the position controller of a permanent magnet linear motor direct drive feed servo system. Firstly, it describes linear motor basic structure, sets forth its working principle and related control strategy. According to the performance requirement of the ultra-precision machine feed drive servo system and the characteristic of"direct drive", the control structure is designed, and the mathematical model of linear motor direct drive feed system is established.On the basis of these studies, the position controller is designed. In order to improve the control accuracy, some control strategies are adopted: (1) P-PI position controller and IP position controller are designed by engineering design plan; (2) In order to reduce the tracing error, the compound controller with a speed and acceleration feed-forward is designed; (3) In machine tool servo system, there exit some disturbance force, which affects the tracing accuracy of the system immensely. In order to conquer its effects, a disturbance force observation model is founded in this paper. And a feed-forward controller in real time compensates for the disturbance force. Thus the control accuracy of the system is increased phenomenally.Theoretical analysis and simulation results show that the designed system is propitious to the ultra precision machine feed system.Finally, using the PMAC as the movement controller of the servo system, experimentation validates the position servo system controller designed in this thesis. The result validates that linear motor direct drive feed system using as the ultra-precision machine feed drive servo system is feasible.