Compensation for position-varying 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. NC machine tools with large travel area sometimes show position-varying lost motion. Conventional step type backlash compensation applied to that lost motion, causes contouring error due to inadequate compensation. The paper presents a model of a two-body system with a position dependent spring and position dependent friction that exhibits position-varying lost motion, and a compensation method for that lost motion introduced from the model. Experimental results show the improved performance of the proposed method.