Research On Testability Requirement Analysis For Equipment

Design for testability (DFT) is a key technique to improve equipment test and diagnosis capability and to decrease life cycle cost (LCC). DFT can also enhance the equipment availability, combat readiness and mission success. As the basis and key stage of testability engineering, testability requirement analysis is the process of confirming testability design content and determining testability indices, according to the operation requirements and constrains. Due to the lack of theory, model and method for testability requirement analysis, there are some significant problems in DFT of complex equipments, such as testability requirements uncertainty, testability indices irrationality, testability requirements and indices empiricism, which influence the application and development of testability engineering.In this dissertation, it is deeply researched the theories and techniques of testability requirement influencing factors analysis, modeling, indices architecture and indices determination. The main contents and conclusions are as follows.1.Analysis on the influence factors of testability requirement for equipment. Firstly, the testability requirement influencing factors for whole system and life cycle are analyzed with the analysis of testability requirement essence. Then, the factors of system requirement, which influence testability requirement, are analyzed, such as mission requirement, functional requirement, reliability requirement, maintenance and support requirement, system performance requirement and usable and reachable technology. Finally, the effect of availability and mission success probability on testability requirement and indices determination is analyzed quantitatively, it establishes the foundation for testability requirement analysis and indices determination.2.Study on the construction technique for testability indices architecture.Firstly the key testability indices set is gained with testability parameters analysis and selection optimization. Secondly it is set up the three-dimensional synthetically testability indices architecture for system structure, mission pattern and project phase. Then with the analysis of the propagation process, indices architecture selection and indices determining process, the output testability indices architecture of testability requirement analysis is designated. Finally it is clarified the relationship among testability indices architecture and indices requirement for demonstration department, design department and users.3.Study on the testability requirement information modeling technology based on UML-GSPN.The testability requirement information modeling method is proposed based on combination of unified modeling language (UML) and Generalized Stochastic Petri Nets (GSPN). It proposes the UML-GSPN integration modeling method for testability requirement information, and sets up the testability requirement information description model based on UML, which can effectively unify the natural language described testability requirement influencing factors with an information model framework. Base on the previous models, the transition method from UML model to GSPN is put forward to make the testability information transform from non-formalized mode to formalized mode, which establishes the foundation of testability indices requirement.4.Study on the testability requirement modeling and indices determination method.(1) Firstly, it is proposed the normal testability requirement analysis model and indices determination method based on GSPN, which can determine system testability indices reasonable. Secondly, for system has requirement informations of its sub-level and the requirement informations between different levels are relevant, the multi-level testability requirement analysis model is built up. Then, the whole GSPN is decomposed into multi-reduced subnets. Finally, based on the equivalent transition principle, testability indices requirements of each level are analyzed and solved step by step, with combination method of qualitative analysis and quantitative computation. The results indicate that the testability indices about system level and other levels are more scientific and reasonable. This method is novel and effective for complex equipment testability analysis and indices determination.(2) Aiming at the multi-phased missions and multi-state transitions in complex equipment, it is proposed a phased-mission system (PMS) testability requirement analysis model based on deterministic and stochastic Petri net (DSPN), which can effectively describe multi-phased mission and system state information about testability requirement by phased net (PhN)and system net (SN). It is built up a transition model between phased mission state, which combines system performance requirement and phased mission requirement effectively. By analyzing the DSPN model, the system level testability indices are determined, which satisfy the system performance requirement and relative constrains. Finally, the application results demonstrate the validity of the method.5.Method validation and engineering application.The application in a missile system validates the efficiency of the presented methods. The testability requirement model based on UML-GSPN is constructed by collecting and inputting the testability requirement influencing factors. Then it is respectively determined multi-phase mission system indices architecture, system level indices architecture and sub-system level indices architecture. Finally the synthetically testability indices architecture of missile system is constructed. The results show that the testability requirement analysis and indices determination method is feasible and reasonable.In summary, testability requirement influencing factors and indices architecture are clarified in the paper, and testability requirement description model is built up based on UML-GSPN. Based on the previous research, a method of testability indices determination is set up to solve the testability requirement analysis problem effectively. These researches have some academic and practical significance.