Study on the development of a three dimensional linear encoder system for in-process motion error calibration and compensation of machine tool axes

In-process measurement of volumetric accuracy is an effective method to enhance the machine tool motion accuracy for quality machining operations. This paper describes a new three dimensional linear encoder system for measuring the on-axis volumetric accuracy of machine motion. The proposed system consists of three cross-grid grated scales with three sensor-heads, each of which includes six opto-electronic sensing elements. The system uses a noncontact scanning principle to detect six degree-of-freedom motion errors. These represent three linear and three angular displacements along a moving axis. The evaluation tests on the prototype system have successfully demonstrated the feasibility of the proposed technology