Research Of Circuit Fault Diagnosis Based On Fault Dictionary

The complexity of the intensity of the circuitry is higher and higher, which also provides a great convenience for people’s production and life,therefore, fault diagnosis and proper treatment for the circuit system is getting more and more import,personnel maintenance which is rely on simple fault diagnosis equipment for diagnosis and repair has become increasingly difficult to adapt to modern electronic equipment products.With the development of modern computer technology, digital circuit fault diagnosis is relatively mature, analog circuit fault diagnosis although start earlier, but develop slowly,mixed-signal circuit which include both digital and analog circuits, therefore is more difficult to do fault diagnosis, with the wide application of mixed-signal circuit, the study of mixed-signal circuit fault diagnosis has important significance.In this paper, based on the existing fault diagnosis technology, study the fault dictionary method and the characteristics of the mixed-signal circuit, using transient simulation analysis method which need not to separate digital and analog circuits or add other components,based on circuit functional angle processing the signal extraction and parametric work to complete the complex waveforms circuit fuzzy sets division.Focuses on the traditional optimal test point selection method, the comprising and exclusion method, which are combined based on the total number of fuzzy sets, fault variance, measuring point entropy, and put forward a selection algorithm based on the measured points estimated optimal test point, select the optimal complete set of test points, lower fault dictionary complexity when measured, Realize the mixed-signal circuit fault diagnosis software based on fault dictionary, achieve the purpose of fault diagnosis. The main contents are as follows.At first fault diagnosis technology is introduces, which includes digital circuits,analog circuits and mixed-signal circuit and fault dictionary methods was studied.Then the key technologies and the improvement the of fault dictionary method is introduced,based on the study of related technologies of the traditional fault injection and simulation method, division of fuzzy sets method, the optimal choice of test points method, according to the characteristics of mixed-signal circuit. Fulfill the automatic fault injection and transient simulation method, division fuzzy sets method based on semaphore features, Optimal test point selection algorithm based on estimated measuredpoints.Finally fulfill the fault diagnosis test for a mixed-signal circuit, build the fault dictionary by the fault diagnose software based on fault dictionary method, which achieve a good fault isolation effect, and achieve fault component positioning work,which has a certain practicality.