Objective

Field testing of the EM-63 sensor (left) and the GEM-3 senson (right).

Successful discrimination between unexploded ordnance (UXO) and clutter depends on the existence of characteristic attributes associated with UXO that are consistent across all examples of an ordnance type and that distinguish them from clutter. However, real UXO are often dented, bent, broken, or otherwise damaged. This produces variability in their electromagnetic induction (EMI) response and complicates the problem of UXO/clutter discrimination. The degree of consistency from one item to the next within a given class or sub-class of UXO is related to the peak theoretical performance of any discrimination scheme used to classify targets, and this represents a fundamental limit to the performance of all discrimination schemes. This project was aimed at quantifying UXO variability by measuring a large number of real UXO and expressing variability in physically meaningful terms. Similar to navigation errors, modeling errors, and sensor noise, inherent UXO variability degrades discrimination performance, but unlike these other sources of error, it cannot be reduced through better engineering or better processing tools.

The overall objective of this project was to promote improvement of discrimination algorithms by quantifying the inherent variability of UXO themselves. This information is useful for transitioning research results, which are often obtained under controlled test environments utilizing small numbers of representative samples, to complex and diverse real-world settings.