Analog system-level fault diagnosis based on a symbolic method in the frequency domain

Concurrently, a symbolic approach for analog system-level fault diagnosis and a systematic approach to maximize the fault location capability are proposed. This unified approach is realized as a result of combining the simulation before test (SBT) fault dictionary diagnosis method with a symbolic approach. The traditional SBT fault dictionary method is often costly and inefficient because of a high number of simulations, but it can become very efficient when a symbolic approach is employed. This symbolic approach only requires one analysis for circuit topology to generate the network transfer function and a parameter substitution to obtain the frequency response (or time response) of the system. An efficient program is developed to deal with the frequency responses of the system to provide the optimum testing point set, and to automatidy generate the fault dictionary. The “distance” between the measurement data and the frequency responses from the fault dictionary is evaluated to determine the diagnosis results. A practical example is presented in order to illustrate the main features of this proposed analog system fault diagnosis approach.