A new approach to biaxial cross-coupled control

Abstract

Cross-coupled control (CCC) has been developed to improve contouring performance for biaxial contour motion systems. However, it is complicated to apply the CCC to arbitrary contour motion because additional calculations are required to obtain the variable cross-coupling gains. In this paper, a new approach to CCC is proposed to efficiently reduce the computation of cross-coupling gains for arbitrary contour commands. According to the analysis of variable gain cross-coupled control, the magnitude and direction of the contouring error can be used to determine the value and direction to be applied in contour compensation for each axis. Thus, the contouring error vector is used here to derive the new CCC approach. The estimated contouring error vector is defined as a vector from the actual position to the nearest point of the line that passes through the reference position tangentially. Thus, the implementation of CCC becomes much more direct with only one simple formulation for cross-coupling gains. Finally, the experimental results on a CNC machining center show that the proposed CCC approach efficiently reduces the contouring error during arbitrary contour motion. Moreover, the calculations required to obtain the variable gains of the CCC are significantly reduced.