Uncertainty analysis of workpiece orientation: a mathematical decision support system for circular geometry measurements

Abstract

The article aims at quantifying and controlling the measurement uncertainties contributed by the workpiece orientation during the automated inspection of a circular geometry by using Coordinate Measuring Machines. The paper proposes a mathematical model to compute angular error and circular variance to quantify and minimize the measurement uncertainty associated with the workpiece orientation. The proposed methodology involves part programming, acquisition of the raw coordinate data points through experiments, identification of the potential factors influencing measurement results, development of the mathematical model to estimate and correct measurement uncertainties, and finally supports the user to minimize the variations in the measurement results. It was found that diameter, circularity and centroid measurements are affected by the workpiece orientation and probe start position has a significant effect on the measurement results. The proposed model reduced uncertainties as the data tends to spread uniformly along the geometric feature. The overall measurement results improved by 12 %.