Precise Variable-Gain Cross-Coupling Contouring Control for Linear Motor Direct-Drive Table

A novel contouring control structure including control strategies for X-Y linear motor direct-drive table is proposed in this work. The contouring control structure contains two discrete-time terminal sliding mode tracking error controllers for each axis and a PID contouring error controller for the estimated contouring error. As for the process to estimate the contouring error, a universal variable-gain cross-coupling estimator is designed. At last, the effectiveness of the contouring control structure is proved by the experiments to track the reference circular contour.