Nostrum: Constraint Directed Diagnosis

Nuttall, Simon (1990). Nostrum: Constraint Directed Diagnosis. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000fc56

Abstract

This thesis describes the design, implementation and use of NOSTRUM, a computer program that diagnoses faults in electrical and mechanical devices. The diagnosis is driven from a model of the components of the device. The model itself represents the operating principles of the component parts of the device. By choosing to model the operating principles on a constraint based system it is easy to predict the consequences of infringement of those operating principles, and also to back propagate from an observed symptom to a hypothesized fault.

NOSTRUM interacts with the user, proposing tests to perform on the device and asking if the predicted consequences of a hypothesis are observed. NOSTRUM allows experiential knowledge in the form of fault models to be added to modify and speed up its search strategy.

At a general level NOSTRUM can perform diagnosis in novel situations, pinpointing a break in the structure of the device whilst not necessarily being able to describe the nature of that break.