Soichi Ibaraki, Kyoto University

This paper proposes a new measurement device to measure the volumetric accuracy of machine tools, which is called "open-loop laser tracker" in this research. The conventional laser tracker automatically controls the laser direction to the target (a reltroreflector attached to the machine spindle), but this mechanism is complex, higher-cost, and its effect on the estimation uncertainty is difficult to assess. Unlike the conventional laser tracker, this device controls the laser direction by regulating the angle of rotary axes calculated from the commanded target position and the device position without observing the actual target position (in “open-loop” control manner). This eliminates the automated tracking mechanism, which may significantly reduce its manufacturing cost. This paper investigates the uncertainty of the proposed measurement method. As a case study, the volumetric accuracy of a machine tool is measured by the proposed method, and then compared with conventional measurements.

Keywords: Open-loop laser tracker, volumetric accuracy, machine tools, uncertainty.