Precision RIC Contouring Control Method for Polar Coordinate Motion Systems

For precision planar contouring control systems widely applied in industrial scenarios, additional contouring control action are usually added to two axes respectively to make the actual contour as close as possible to the reference one. In this paper, planar motion is described in polar coordinate system, based on which a novel master-slave control mode is utilized to enhance contouring performance. Compared with various existing contouring control methods, the proposed one can improve the coordination between two axes by compensating the reference trajectory of only one axis, so as to guarantee the contouring performance in a simpler way. Specifically, polar-radius error, different from traditional contouring error, is firstly defined to describe the deviation between the actual contour and the reference one. And real-time iterative compensation (RIC) scheme is designed for the radial motion axis to improve its trajectory tracking performance and to suppress contouring error indirectly. Comparative experiments with different error definition and control modes are carried out on machine tool systems to illustrate the effectiveness of the proposed method.