Fault Isolation with Estimated Frequency Response

A.P. Loh, J. Lu, and K.F. Fong (Singapore)


fault isolation, frequency response, generalized likelihood


In this paper, a frequency domain fault isolation method for linear time-invariant system is proposed. A fault is as sumed to cause a change in one of the parameters of the transfer function of the plant, leading to a change in the frequency response. Based on this changed frequency re sponse, a fault isolator is designed to determine which pa rameter has changed. This is achieved without any estima tion of the parameter value. The proposed method captures the changes in the frequency response by an observation vector involving estimates of the frequency response. The decision on which parameter has changed is based on the generalized likelihood ratio test. The performance of this isolator is defined to be the probability of correct isolation and it can be calculated easily using the idea of 'correct' spaces. Simulations are given to illustrate the results.

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