The role of extrinsic factors in industrial task-specific uncertainty

The measurement of large components using portable measuring equipment is important to many industries, including ship-building and aerospace. Portable measuring instruments - such as laser trackers, laser radar, indoor GPS, and other systems - are used to obtain measurement data for process control, assembly alignment, or geometric conformance decisions. Traditional uncertainty estimations often focus on the measuring instrument and its performance as a primary contributor to the overall uncertainty for specific measurands. The research reported here focuses on the uncertainty contributors that are due to extrinsic effects such as part deformation due to gravitational loads and thermal distortion of the workpiece, where the uncertainty contribution from the instrument is considered insignificant in comparison.