Re-engineering the test development process

Traditional development of the diagnostic portion of test programs required a highly labor-intensive process of going through pages of schematics and circuit diagrams, hypothesizing all potential failure modes, and developing discrete test paths to ensure fault propagation. In the re-engineered test process, model-based diagnostic software is separated from test software. In run-time, the diagnostic software provides dynamic fault isolation without complex diagnostic test programs. In the re-engineered test process, the fundamental nature and structure of the test process has been changed. The interpretation of the tests is done by dynamic interaction of the product or process knowledge base with an Al Inference Engine that on-the-fly interprets test information based upon all information it receives-in any order. In this type of test program structure, no code is duplicated. The fist of faults is clearly identified and diagnostic data for each fault is kept in one location. Model-based reasoning makes diagnostics affordable for limited production testing and effective for complex system test. The re-engineered test process also supports design of embedded fault management systems, trade-offs between on-line and off-line test, as well as automatic production and field service diagnostics