Testing IR Detectors With An Expert System
Paul R. Norton, Judy Slager, John Stannard · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1989
An expert system has been developed to assist in analyzing IR detector test data. This data is taken in the production of Common Module detector-dewar assemblies. These assemblies contain on the order of 1500 internal electrical connections, and test data may consist of more than 1500 data items. Testing is done at several stages in the manufacturing sequence to determine if any rework is needed prior to the next assembly operation. Rework of a defect should be done at the earliest possible stage to minimize cost and jeopardy to the unit. Thus it is important to identify defects from their signature in the test data with consistency and accuracy. Coldfinger is the name of the expert system designed to help in this task. It was written in PROLOG and implemented on a Macintosh PC. The user friendly interface of the Macintosh made factory training easier and faster. Coldfinger's software code contains 165 facts, 348 tools and 138 rules. The facts describe the electric wiring topology and adjacency of connections, including probabilities for shorts between any two wires. The tools are used to compare test data results locally and globally. The rules have been distilled from the experience of real production personnel familiar with the product. Coldfinger operates in real time, taking about two minutes to analyze a set of test data with no defects, and only seven minutes with a hypothetical data set containing a large number of defects. Unlike real experts, Coldfinger does not eat or sleep so that assistance in decision making is available around the clock.