Publications

The combination of digital image correlation (DIC) and new high and ultra-high speed digital imaging systems has yielded an extremely powerful tool for measuring the full-field results of explosively driven events. However, limitations in the hardware and the inherent difficulty of synchronizing camera clocks beyond a megahertz have raised questions about possible errors in the DIC results due to a lack of synchronization. This paper explores the synchronization of high-speed cameras experimentally and then uses synthetic images based on the range of experimental synchronization errors to calculate the expected 3D-DIC measurement errors. ©2009 Society for Experimental Mechanics Inc.

Sandia National Laboratories currently utilizes two laser tracking systems to provide time-space-position-information (TSPI) and high speed digital imaging of test units under flight. These laser trackers have been in operation for decades under the premise of theoretical accuracies based on system design and operator estimates. Advances in optical imaging and atmospheric tracking technology have enabled opportunities to provide more precise six degree of freedom measurements from these trackers. Applying these technologies to the laser trackers requires quantified understanding of their current errors and uncertainty. It was well understood that an assortment of variables contributed to laser tracker uncertainty but the magnitude of these contributions was not quantified and documented. A series of experiments was performed at Sandia National Laboratories large centrifuge complex to quantify TSPI uncertainties of Sandia National Laboratories laser tracker III. The centrifuge was used to provide repeatable and economical test unit trajectories of a test-unit to use for TSPI comparison and uncertainty analysis. On a centrifuge, testunits undergo a known trajectory continuously with a known angular velocity. Each revolution may represent an independent test, which may be repeated many times over for magnitudes of data practical for statistical analysis. Previously these tests were performed at Sandia's rocket sled track facility but were found to be costly with challenges in the measurement ground truth TSPI. The centrifuge along with on-board measurement equipment was used to provide known ground truth position of test units. This paper discusses the experimental design and techniques used to arrive at measures of laser tracker error and uncertainty. © 2009 Copyright SPIE - The International Society for Optical Engineering.

Abstract not provided.