Contour error analysis and gain tuning for CNC machining center

One of the most important performance criteria in tuning the gain of position loop controller for CNC machining center is the contour error. We derive error formulae for the linear and circular interpolation which can be applied to the axis-matched and mismatched cases. For the axis-matched case, the derived formula can be easily interpreted in the frequency domain. Based on this interpretation, we propose a gain tuning method for the P and PD controller. The effectiveness of the method is demonstrated in a series of experiments.