Design of trajectory tracking controller for precision positioning table driven by linear motor

In order to achieve the high precision trajectory tracking control of a positioning table driven by Permanent Magnetic Synchronous Linear Motor (PMSLM), This paper designs a hybrid trajectory tracking controller. The controller combines Model State Feedback (MSF) and Velocity/Acceleration Feedforward controls (VFC/AFC) to ensure the precision of a positioning table. Based on the principles of Internal Model Control (IMC) and the identified model of the positioning table, a MSF controller is proposed and the parameter calculation methods of the MSF controller are presented. Using the MSF model, a cascade PID/MSF controller is designed. The PID/MSF cascade controller is incorporated with the VFC/AFC control to construct a hybrid PID/MSF+VFC/AFC trajectory tracking controller. The VFC in the trajectory tracking controller is used to improve the velocity command response and the AFC is used to remove the overshoot induced by VFC without lowering the position loop gains. The hybrid trajectory tracking controller is implemented in the MATLAB/dSPACE real time control platform. Simulation and experimental results show that the controller can meet the requirements of precision tracking control and can achieve the tracking accuracy of ±0.028 mm and the positioning accuracy of ±4 μm for a precision positioning table driven by PMSLM.