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Freezing Time: Dynamic Laser Tracker Measurements with the Pixel Probe using Temporal Aliasing

Published

Author(s)

Joshua A. Gordon, Steven S. Borenstein

Abstract

We present a non-contact technique for measuring objects in motion with a laser tracker without the laser tracker needing to follow the object. This method allows the dynamic state of an object to be measured while, to the laser tracker the object appears to be stationary. Through temporal aliasing, this technique decomposes the dynamic frame of an object into an instantaneous stationary frame of reference with respect to the laser tracker. The PixelProbe and laser tracker are used to demonstrate this method. The frame rate of the three cameras in the PixelProbe are adjusted to selectively alias the motion of an object into a stationary frame of reference. By triggering the cameras in the PixelProbe at an appropriate frequency the object in motion appears stationary to the PixelProbe and therefore to the laser tracker as well. This allows spatial metrology to be performed on a dynamic object without the need to operate the laser tracker dynamically. We present measurements of rigid optical targets under both stationary and dynamic conditions. The dimensions of the rigid targets should be the same for both the static and dynamic cases and therefore these targets provide a control experiment. These data are used to validate this technique by providing a direct comparison of accuracy between the use of aliasing with the PixelProbe to the stationary case. Measurements for a non-rigid body are also made where a mass at the end of a string is constantly rotated at several frequencies. The 3D dynamics motion of the rotating mass is measured and compared to the predictions of Newtonian mechanics. We show that through the purely spatial measurements made with this technique, the rotation frequency of the mass can be determined to
Citation
Journal of the CMSC

Citation

Gordon, J. and Borenstein, S. (2016), Freezing Time: Dynamic Laser Tracker Measurements with the Pixel Probe using Temporal Aliasing, Journal of the CMSC, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=921153 (Accessed April 22, 2024)
Created October 1, 2016, Updated March 22, 2019