Optimum test point selection method for analog fault dictionary techniques

Abstract

Fault dictionary has two types of online and offline calculation. Online calculation is simple, but offline is excessive and time-consuming. In order to reduce the computation time and dimension of fault dictionary, optimal test points selection is very essential. So, the main purpose, fault isolation, is achieved in a short time. In this paper a new efficient method to select an optimum set of test points for fault diagnosis is proposed. At the first, a fault-isolated table is constructed to pick out the special test points from the candidates. Then, the isolation ability of special test points has been considered. If they can’t isolate all of faults, the fault dictionary is rearranged. Therefore, the special test points and isolated faults are eliminated from the table of fault dictionary. In this step, the test point with more single fault is added to special test points. This step is repeated to isolate all of faults. The proposed method is applied on two-stage operational amplifier. By this method, all of faults for this structure are isolated. The computation requirements are very simple than the other methods. In this circuit, the 0.045 s is needed to isolate all of circuit faults. According to the results, it’s clear that the method is a good solution to minimize the size of the test points set. Also, it can be a practical method for medium and large scale systems.