Use of the Concurrent Engineering Tool Set for Automated Diagnostics

One of the most significant innovations in test engineering is Giordano Automation's Concurrent Engineering Tool Set (CETS). CETS consists of a development tool and a run-time tool. The run-time tool, Diagnostician, provides automated diagnostics and is seamlessly integrated into any test environment. The development tool, the Diagnostic Profiler, assists the engineer in preparing the run-time diagnostic knowledge base.

The Diagnostician is an implementation of a new paradigm for diagnostics: model-based reasoning. Model-based reasoning means that a diagnostic model of a system or item, derived from design data, serves as the basis for diagnostic reasoning. The diagnostic model is independent of the test program and independent of the sequence of tests that are run.

In the new paradigm, a model-based diagnostic software object called a Diagnostician is used in lieu of programmed No-Go flow paths. In run-time, the Diagnostician provides dynamic fault isolation without complex diagnostic logic paths, by reading test results. The diagnostic logic is not "fixed" to a pre-determined, static diagnostic tree, but rather is dynamic. The overall object-oriented structure enables dynamic interpretation of test results - test results can come from any source, in any order, and with as many or as few test results at a time as the test source can provide. Static test trees, on the other hand, are based upon one test result at a time, in a pre-determined sequence, and from a fixed test source. If this rigid structure is not precisely followed, the diagnostic process basically falls apart - leaving the technician hanging, and without an alternative solution.

The Diagnostician contains a diagnostic model of the item automatically converted from design data. The model is in the form of a connectivity matrix which represents the propagation of faults (rows in the matrix) to observable measurement locations and the coverage of tests that Pass or Fail (columns in the matrix). When used in run-time, the software algorithms and knowledge base (matrix) operate to isolate faults without troubleshooting sequences and without hard-coded diagnostic test programs.

In run-time, the object or Diagnostician, interprets, in real time, test results to perform fault isolation. The concept of object-oriented programs is taken full advantage of by dealing with the diagnostic logic as an independent entity in the test program. By thus separating diagnostic logic from test, the test program becomes significantly simpler. Further, the diagnostic logic contained in the software object can be rehosted to any platform without any problem, because it is simply a binary file.

Using the Diagnostician, the fundamental culture of diagnostics has been changed. Tests perform measurements and data collection and determine if those measurement are within acceptable ranges. The interpretation of what it means if the measurement has passed or failed is done by the Diagnostician, which dynamically, on-the-fly, interprets test information based upon all information it receives in any order.

The Diagnostician makes use of Artificial Intelligence in the form of "Minimum Set Covering" algorithms that interpret the "Cones of Evidence" produced by both pass and fail test result data. These reasoning techniques provide for fast, accurate, flexible diagnostics, and can also isolate multiple faults. Static test trees, on the other hand, are limited to a "single fault assumption" and in multiple fault situation, can become very fragile.

Next

Back to Table of Contents

Send mail to webmaster@giordano.com with questions or comments about this web site.
Last modified: December 27, 2001