Method of testability evaluation using hierarchical testability model

The layered and modularized design is always used in complex electronic equipment,where the maintenance level and test requirement are both characterized by hierarchy configuration. Therefore,a novel evaluation approach was presented based on hierarchical testability model. The multi-signal flow graph model has ability to present multi-fault factors,according to the hierarchical classification based on maintenance level and physical structure of equipment,the multi-signal flow graph model could be established for each level respectively. For any part which can't be tested or maintained,the multi-signal flow graph model would be established on lower level; thereby the hierarchical testability model was built up. The hierarchical dependence matrix was obtained based on above model,and then the testing level of equipment on each maintenance level was obtained by using the mathematical model of testability evaluation. The analysis results of example prove that this method could effectively evaluate the testability levels of equipments in different situations,at the same time this method could provide available guidance and assistance for the design of testability and maintenance.