Model-based Disturbance Attenuation for Linear Motor Servo System

This paper presents a method using model-based disturbance attenuation (MBDA) to reject external disturbances, such as frictional forces, cutting forces and load variations for a permanent magnet linear synchronous motor (PMLSM) with high precision and micro-feed for CNC machining centers. In this method, a nominal plant is designed in parallel with the plant. Through the output feedback, the error signal, which is the difference between the plant output and the nominal plant output, is achieved by means of a compensator controller in the velocity loop. Accordingly, disturbance attenuation can be attained. In addition, an integral and proportional (IP) controller is designed directed toward the velocity loop to cater the fast tracking and resist disturbance greatly. Simulation results show that this proposed method has quick-response speed and strong disturbance attenuation. Moreover, machining precision can be improved remarkably