水平多関節型位置決め機構の精度特性に関する研究（第２報）―任意３点法によるリンク長の単純校正と広領域の位置決め精度向上の検証―

Abstract

A Calibration method is discussed to improve the positioning accuracy with a planer multi-joint positioning system. A measurement system, which was constructed in the previous report to realize a measurement resolution of 1.2μm over the global range of 350×150mm, is used for the calibration. At first, the effect of the link length error on the positioning accuracy is considered analytically. It is clarified that the positioning error obtained in the previous report is caused mainly by the link length errors. Next, a method of calibrating the link length is discussed to improve the positioning accuracy. The equations are formulated to derive the link length from the positioning errors on arbitrarily selected three points. Because 32 points are given on the reference board for the measurement, 32C3=4960 different pairs of link lengths are obtained from the measured results. A method is proposed to determine statistically the optimum value of the link length from the 4960 pairs. The positioning experiment is performed again by using the calibrated link lengths. It is verified that the RMS value of the positioning bias errors decreases to 24μm that is equivalent to the positioning resolution of the system.