Design and calibration of an artifact for evaluating laser scanning articulating arm CMMs used for measuring complex non-concurrent surfaces

Published

October 30, 2015

Author(s)

Vincent D. Lee, Steven D. Phillips, Craig M. Shakarji, Jeffrey Hosto, Jeffrey Huber, Gillich Barbara

Abstract

Dimensional metrology is a foundational science finding applications throughout modern technology, including the testing of human-worn body armor designed to mitigate damage from kinetic projectiles fired from small arms. We describe the design and calibration of artifacts intended as in situ check standards for articulating arm CMMs equipped with laser scanners used to evaluate the effectiveness of the body armor in standardized tests. The tests involve firing a projectile into body armor supported by a soft substrate made from modeling clay, leaving an indentation in the clay that is an indication of the blunt-force trauma that would be experienced by the wearer. Assuming that the projectile didn’t fully pierce the armor, which would render it an automatic failure of the armor, the maximum depth of the indentation relative to the pre-deformed surface is measured to test if it is below their threshold for safety. The US Army initiated a collaboration with NIST to develop quantitative check standards to be used in live fire testing. We describe two different check standard designs, differing in how they address the issue that the pre-impact surface which is destroyed during the formation of the post-impact surface. The calibration of the distance between these complex freeform surfaces poses an interesting measurement uncertainty evaluation effort that we describe in detail.

Proceedings Title

30th ASPE Annual Meeting Proceedings: Precision Metrology

Conference Dates

October 31-November 5, 2015

Conference Location

Austin, TX

Conference Title

30th ASPE Annual Meeting

Pub Type

Conferences

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Keywords

Freeform metrology, dimensional metrology, laser scanning, CMM, Coordinate measuring machine

Citation

Lee, V. , Phillips, S. , Shakarji, C. , Hosto, J. , Huber, J. and Barbara, G. (2015), Design and calibration of an artifact for evaluating laser scanning articulating arm CMMs used for measuring complex non-concurrent surfaces, 30th ASPE Annual Meeting Proceedings: Precision Metrology, Austin, TX, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919256 (Accessed October 26, 2025)