Testability Modeling And Analysis Of Hierarchical System

Testability is a design characteristic which reflects whether the system internalfault could be detected and isolated accurately and timely. A high level of testabilityguarantees system a durable and steady performance. With the integration andminiaturization of the complex and sophisticated electronic systems, a significantincrease in the difficulty of testability analysis and fault diagnosis happens.However, the demand for system testing of many critical area such as aerospace andmilitary is higher and higher. It is indispensable of design for testability to improvethe level of system testability.As the key of design for testability based on the model, testability modelingand analysis can evaluate testability level of system both in qualitatively andquantitatively perspective, guide designers to make perfect testing schedule anddiagnosis strategy, thus save test time, reduce test costs, and improve test efficiency.Up to now, there is not a general method suitable for the system level, while theactual test and maintenance works are mostly aimed at the system level. Therefore,studying the method of testability modeling and analysis for system is of greatsignificance. This paper puts system hierarchical division, testability indexallocation, testability modeling and analysis together to build a testability evaluationsystem. Main work of the paper includes the following sections.At first, research in the demand for system hierarchy division of actual test,diagnosis and maintenance are done, and the principles and methods of systemhierarchy division are proposed. The general procedures and mathematical oftestability index allocation are specified. Three testability index allocation methodsare studied. And their similarities and differences are compared in terms of factorsconcerned, allocation difficulty and result.Besides, the fundamental, structure description, testability analysis methodsand procedures of FST(Fault-Signal-Test) model are studied. The shortcoming ofFST model is pointed out: it ignores probabilistic information of test and is unableto deal with the uncertain relationship between tests and faults. For this reason,probability integration FST model is proposed and corresponding testability analysismethods are provided.And then, the development of the hierarchical system testability modeling andanalysis software is completed. The each function module in the overall architectureof this software, including the hierarchical modeling platform, model informationextraction module, testability index allocation module and testability analysismodule, are designed. The comprehensive evaluation of system testability model isrealized. Finally, the hierarchical testability model of a certain electronic reconnaissancesystem is modeling respectively by the software designed in this paper and theauthoritative software TEAMS. Testability index allocation and Testability analysisof its testability model are accomplished; the results of both pieces of software arecompared to actual test engineering statistics to verify the validity and reliability ofsystem testability modeling and analysis methods proposed in this paper.