Modeling and Compensation for the Exponential Type Lost Motion to Improve the Contouring Accuracy of NC Machine Tools

Lost motion is a major disturbance to the contouring accuracy of NC machine tools. Although NC machine tools with plain bearing guideways perform high alignment accuracy, they sometimes show the exponential type lost motion. Conventional step type backlash compensation applied to that lost motion, causes contouring error due to over-compensation. This paper presents a model of a two-body system with a nonlinear damper and a nonlinear spring that exhibits the exponential type lost motion. A compensation method for that lost motion is introduced from the model. Experimental results show the improved performance of the proposed method.