Study On The Equivalent Fault Injection Technique And Its Application In Testability Test

Testability is one of the essential quality characteristics in modern equipment.In order to verify the testability design and evaluate the testability level,the testability test needs to be implemented.In the testability test,there are many faults that cannot be injected due to the fault location and bad influences.How to implement the testability test without breaking the integrities of products? It is a pending problem in the testability test.Aiming at the problem of fault injection in the testability test,the principle and types of the equivalent fault are analyzed in the dissertation with the purpose of testability test.A fault behavior analysis model was established based on extended dependency model.The method of equivalent fault selection is proposed and applied to the testability test of radar system.The major contents of the dissertation are as follows.1.The principle of equivalent fault and range of application.The reason of fault that cannot be injected was analyzed according to the content of the testability test.The equivalent fault in the dissertation is defined.Equivalent fault is classified according to the equivalent degree between different faults.The influences of different equivalent types were analyzed,and the range of application with each equivalent fault type is defined.2.Fault behavior model based on dependency modelDealing with the problem of fault injection,the principal idea of equivalent fault injection is proposed.In order to obtain the equivalent fault samples,the fault behaviors need to be analyzed.With the fault transfer characteristics and principle of fault equivalent,a fault behavior model is pointed out.The characteristics of internal fault behavior are presented by the internal output function parameter of module.By adding the fault behavior model of the module and a logic switch,the fault behavior of the module,the relationship between modules and the test points can be described.3.The method of equivalent fault selectionIn order to obtain the equivalent fault sample,a method of equivalent fault selection is proposed,the fault-test and fault-signal-test dependency matrix are presented based on the fault behavior model and reachability algorithm.The test set and test point set of each fault were calculated and compared with the original fault,the optimal equivalent fault sample was obtained according to the relationship between the test point set and the test set.4.Application and verification in a radar systemThe fault behavior of each module was analyzed with a radar frequency source system.The fault behavior model was established,and dependency matrix was obtained based on the fault behavior model,and the test set and test point set of different faults were calculated.Fault injection was carried out with the equivalent fault samples.The equivalent of the fault is verified by comparing the results of fault injection.