Contouring control of smooth paths for multiaxis motion systems based on equivalent errors

This study is concerned with the contouring control for multiaxis (n-axis) motion system. The equivalent errors, consisting of n - 1 equivalent contour errors and 1 tangential error, are proposed to simplify the design of contouring controller. Instead of the actual contour error, which is, in general, a complicated function of axial positions, the equivalent errors are taken as the new control objective. The contouring control problem becomes the stabilization of the equivalent errors. To this aim, the method of integral sliding mode control is employed. The proposed method can be applied to both linear and nonlinear plants following arbitrary smooth paths. Numerical and experimental results on an XY table driven by linear motors clearly verify the theoretical analysis. An experimental comparison of the proposed method with conventional methods is also provided for an XY table driven by conventional motors. The results show that the proposed method is especially useful for high-speed contouring applications.