A diagnosability analysis by means of fault distance

A new concept of fault distance is introduced in a failure-diagnosis model. Diagnosability measures such as t-fault diagnosability and t/s-diagnosability are expressed in terms of the fault distance. A new diagnosability measure of partial t-fault diagnosability characterized in terms of fault distance is proposed. In addition, the fault distance of various types of self-diagnosis models are expressed in graph theoretical terms. Applying the fault distance to various types of self-diagnosis models, conditions for diagnosabilities of these models, which have been studied separately, are obtained in a unified manner. Conditions for t-fault diagnosability and sufficient conditions for t/s-diagnosability are obtained with this fault distance.