The Research On Screen Theory And Information Fusion Approaches For Fault Diagnosis Of Analog Circuits With Tolerance

With the rapid development of microelectronics, the need for automatic tests and fault diagnosis of analog systems is becoming an increasingly critical requirement in circuit fabrication and maintenance. Unfortunately, the progress of analog circuit fault diagnosis from the fundamental theory to sophisticated technology has been hampered by the presence of component tolerance and other factors. Up to now, neither efficient methodology nor software applied widely to actual circuit diagnosis has emerged in the world. Thanks to the increasing mature of intelligent information processing technology and application. It provides great possibility to overcome the difficulties in analog fault diagnosis.In this dissertation, the research is focused on seeking after fault diagnosis theory and approaches for analog circuits with tolerance effort. The application of fault screen based diagnosis methods to tolerance circuits and the information fusion based fault diagnosis technique for tolerance circuits are dealt with in detail. Under consideration of component tolerance, the strategy and algorithm of K fault screen diagnosis, the establishment of fuzzy fault screen dictionary and its application, the fault diagnosis principle based on a multilayer information fusion model, the diagnosis strategy and algorithm based on decision fusion of different diagnosis methods, the diagnosis strategy and algorithm based on intelligent information fusion are proposed. Both theoretical analysis and simulation results show that they are more efficient and practical than traditional methods.Equal input / equal output K fault screen method has excellent practicality, but it is invalid for tolerance-circuit diagnosis because of the difficulties in obtaining screen excitation and locating faults. Therefore, the single-objective optimization based K fault screen method applied to tolerance circuits is proposed by means of optimization technology, probability theory and statistics, fuzzy theory, numerical analysis and matrix theory. It has small computational work and low fuzziness between faults and tolerance. Based on this, the tolerance-circuit fault screen theory and method based on multi-objective genetic optimization algorithm is developed, which establishes the mathematics model of fault screen by multi-objective optimization and searches for the optimal excitation by genetic algorithm. As a result, the accuracy and applicability...