Offline fast modification of position loop gains for five-axis machining

Abstract

Servo matching (SM) controls the contour error (CE) by coordinating the tracking error (TE) of each axis, which is a basic strategy of CE control. However, the SM, especially the five-axis SM approach, has not been widely used in engineering due to the long time taken to compute the modification of the position loop gain (PLG). This paper establishes the functional relationship between the five-axis PLG and part CE based on the Jacobian matrix. An offline PLG fast modification approach for part CE in five-axis machining was proposed based on the above criteria. Through this method, the five-axis machine tool could modify the PLG of each axis for specific parts and improve the contour accuracy of the parts. Compared to the traditional approach, the servo control model prediction, forward kinematics transformation (FKT), and tool contour pose are omitted based on the proposed approach. Consequently, the computational burden is greatly reduced, the computing time is reduced by more than 98%, and the average contour accuracy can be improved by more than 54%.