Design of precise multi-axis motion control systems

In this study, to achieve the multi-axis cross-coupled control (CCC) to render contouring accuracy for arbitrary contour commands, the estimated contouring error vector which is constructed by the tracking error vector and the normalized tangential vector of the trajectory is proposed. Furthermore, this paper introduces the integrated motion systems which combine the feedback loops, the feedforward loops, and the multi-axis CCC to achieve both tracking and contouring performances. The complete system analysis and the novel formulation of the contouring error transfer function (CETF) for multi-axis systems are also provided to efficiently design the integrated controller. Both motion performance of the resultant tracking and contouring accuracy, and the robustness of desirable stability margins can be thus directly achieved. Experimental results on a 3-axis CNC machine are also provided to prove the validity of the present control design.