Testing of Coordinate Measuring System

Coordinate measuring systems (CMSs) determine dimensional (length-based) characteristics of mechanical parts by analyzing 3-dimensional point data acquired on part surfaces. Data analysis software can contribute significantly to the total measurement error of a CMS. Factors affecting software performance include the choice of analysis method, the quality of software implementation, and characteristics of the specific measurement task. However, there are no standard mechanisms to evaluate the effects of these factors on the quality of the measurement results. NIST is developing a Special Test service to evaluate the performance of Gaussian curveand surface-fitting algorithms that are at the core of most CMS software. This service is being defined in coordination with an ASME standards committee developing a new national standard, Performance Evaluation of Coordinate Measuring System Software. The NIST service will be based on this emerging standard, an Algorithm Testing System currently being developed at NIST, and test procedures specific to coordinate measurement tasks. This paper discusses the background, design philosophy, and status of the new service.