Natural local approximation based contouring control for free-form contours

In this paper, a novel contouring control method based on natural local approximation of desired contour in task frame is proposed for multi-axis control systems. Based on local geometry properties, natural local approximation can achieve more accurate contouring error estimation compared with other local approximation methods for both planar and spatial contouring tasks. The contouring controller, integrated with a PD controller cooperated with the feedback linearization technique and a feedforward compensation, is designed to realize the decoupling control of estimated errors in the task frame. Contouring performance can then be improved directly by increasing corresponding controller parameters. Simulations of 3-axis system and experiments on biaxial XY-stage verified that our proposed method can reduce the contouring errors dramatically in high speed and large curvature cases compared with first-order based method.