An iterative contouring error compensation scheme for five-axis precision motion systems

Contouring error is one of the most important performance indexes for multi-axis motion systems, especially for five-axis ones. The contouring control performance of five-axis motion systems is difficult to improve mainly due to the following two factors. Firstly, the dynamic coupling between the translational and the rotary axes is strong. Secondly, the contouring error in five-axis systems includes tool tip error and tool orientation one, which are difficult to suppress simultaneously. In this paper, a novel contouring error iterative compensation scheme is proposed to realize the coordination control of spatial contouring error with multi-degree-of-freedom. Accurate contouring error estimation is firstly achieved through a numerical calculation method. And then the estimated contouring error is compensated to the reference trajectory by means of the proposed model-free compensation law. By iteratively implementing the above process, the convergence of which has been theoretically proved, the contouring performance can be further improved. A series of experiments have been conducted on a five-axis motion system. The experimental results consistently illustrate that, in comparison with existing contouring control methods, the proposed scheme can achieve excellent promotion of contouring accuracy, especially in extreme contours with large curvature and sharp corners.