Robust Adaptive Contouring Control for Machine Tool Feed Drive Systems

Abstract

Contouring controller design has been widely studied thus far because of its effectiveness for machine tool control. However, plant modeling errors and disturbances such as nonlinear frictions and cutting forces are little considered in existent designs. This paper presents a new contouring controller design that is robust to these unknown factors. First, a contouring controller design based on a coordinate transformation and reference signal adjustment, which has been developed by the authors, is explained. This design enables to adjust control performance of the contour error and the other error component independently to enhance the effectiveness of the contouring control. Next, assuming that upper bounds of plant modeling error and disturbance magnitudes are known, we extend this design to have robustness with respect to plant modeling errors and disturbances. Because unnecessary large values of these magnitudes deteriorate control performance, we further design an estimator of these upper bounds in real time. Comparative experiments demonstrate the effectiveness of the proposed design.