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

摘要

Laser scanners mounted to articulated arm coordinate measuring machines (LS/AACMM) have been recently adopted by the US Army to evaluate ballistic threat mitigation capabilities of human worn body armor. In brief, testing of the armor is performed by placing the article under test against a clay substrate (pre-impact surface), that has been shaped to conform to the concave surface of the body armor, and firing a projectile of a known mass, shape and velocity at it. When the projectile strikes the armor, its kinetic energy is transferred into the armor and clay, resulting in an impact crater (post-impact surface) into the clay known as a back face deformation (BFD), and is an indication of the blunt-force trauma a wearer would experience. The maximum depth of the BFD is used as part of an evaluation criterion to determine if a batch of armor would be placed into service or rejected.