Description of a method and artifact for estimating volumetric uncertainty of coordinate measuring machines
Abstract
Methodology that expresses the volumetric uncertainty of coordinate measuring machines (CMMs) in a single index is developed. A Latin Square Three Dimensional Ball Plate (LS3DBP) is the artifact used to obtain statistically balanced data that are analyzed using Latin square analysis of variance (AOV) to provide quantitative estimates of systematic and random error in the CMM measurement system. Estimates of systematic and random error for the nominal values assigned to the LS3DBP are obtained from analysis of calibration data using one way AOV. A single index, expressed in radial distance, is obtained by combining the systematic and random errors of the artifact and CMM measurement system with the fixed error assigned to the primary measurement system. The Latin square analysis is also used to identify 15 single sources of error in machine geometry by interpretation of the form of axis effects and by using one and two dimensional plots. The notation and methodology developed can be extended to measurement systems other than CMMs. It is currently being used to evaluate robotics machines and numerical control milling machines. The use of the LS3DBP requires 70 percent less time than some conventional techniques to estimate CMM uncertainty in volumetric spaces.
 Publication:

Final Report Bendix Corp
 Pub Date:
 November 1983
 Bibcode:
 1983bend.rept.....J
 Keywords:

 Calibrating;
 Coordinates;
 Displacement Measurement;
 Volumetric Analysis;
 Covariance;
 Milling Machines;
 Numerical Control;
 Random Errors;
 Robotics;
 Standards;
 Instrumentation and Photography