Research On Optimization Technology Of Hierarchical Diagnostic Strategy For Complex Systems

The performance of equipments has been greatly improved with the widely application of high technology. On the other hand, the complexity of technology and structure of equipments significantly raise challenges in equipment testing, diagnosis and maintenance. The problems include poor testing and diagnosis, low accuracy, low efficiency and high consumption on time and cost. Extensive researches and practices show that Design for Testability (DFT) must be carried out concurrently with functional design of equipments in order to fundamentally solve these problems.Diagnostic strategy design, as an important aspect in DFT, is crucial for reducing test cost and improving diagnostic accuracy and efficiency. Recently, great researches about this problem have been carried out all over the world, and a series of findings have been achieved. But, further study is still needed in diagnostic strategy optimization for hierarchical complex systems. Supported by the advanced project, this dissertation mainly aims at the diagnostic strategy optimization for hierarchical complex systems. The main contents are shown as follows.1. A hierarchical dependency modeling is studied.The existing model ignores the hierarchy of failure modes, so they can not support hierarchical diagnosis. Aiming at the defects, at first, the transmission between hierarchies of failure modes is studied. Then, the hierarchy of failure modes is considered and a hierarchical dependency modeling is studied. To get the hierarchical dependency matrix, a dependency analysis algorithm is improved. At Last, several experiments are given to verify the model. The results show that hierarchical modeling is suitable for hierarchical diagnosis.2. The optimization design technology of diagnostic strategy based on hierarchical model is studied.A mathematical description of this problem is firstly constructed. Then, an existing quasi-depth search algorithm is improved, and an optimization technology of diagnostic strategy for hierarchical complex systems is studied. This diagnostic strategy ensures fault isolation to any desired module at desired level, which meets the need of maintenance system.3. Based on theory achievements, a software platform is developed.A CAD tool for dependency modeling and diagnostic strategy designing is developed in C++ language. And a certain type of inertial navigation system is employed as an object to validate the method and the tool. The results show that the proposed diagnostic strategies can accurately and quickly diagnose the hierarchical system with low cost, which satisfy the testability requirements.