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 exponential-type lost motion. Conventional step-type backlash compensation applied to that lost motion, causes contouring error due to overcompensation. This paper presents a model of a two-body system with a damper and a nonlinear spring that exhibits the exponential-type lost motion, and a compensation method for that lost motion introduced from the model. Experimental results show the improved performance of the proposed method