Extended Kalman filter-based disturbance feed-forward compensation considering varying mass in high-speed permanent magnet linear synchronous motor

A disturbance feed-forward compensation method based on 7th-order extended Kalman filter (EKF) is proposed for permanent magnet linear synchronous motor (PMLSM) servo system which is vulnerable to the influence of external disturbances, such as friction force, force ripple and so on. Firstly, a disturbance model which consists of position-dependent functions was developed and utilized as a disturbance feed-forward compensator. Then, the initial position and the varying mass information of plant were estimated by the 7th-order EKF and reflected to the disturbance feed-forward compensator. In addition, the coefficients of the disturbance model were adjusted adaptively to create synchronization between the model and real disturbance and achieve the purpose of varying mass estimation and disturbance compensation. Finally, the system simulation and experiment results confirm that the proposed method is effective and feasible. The PMLSM servo system based on 7th-order EKF has superior performance in disturbance compensation, and it is not affected by the varying mass of PMLSM.