HP Labs Technical Reports

Derivative Estimation for Diagnosis

Barford, Lee; Manders, Eric; Biswas, Gautam; Mosterman, Pieter; Ram, Vishnu; Barnett, Joel

HPL-1999-18

Keyword(s): signal processing; signal interpretation; signal classification

Abstract: In engineering systems, diagnosis is the process of detecting anomalous system behavior and then isolating the cause for this behavior. This report is concerned with the detection and isolation of abrupt faults through analysis of the transients that occur after the fault. We have developed a comprehensive framework for monitoring and diagnosis of dynamical systems that attempts to overcome the difficulties associated with quantitative techniques. A key step in our monitoring and diagnosis framework is the transformation of measurements into symbols that encode the trends in the measurements. That is, the symbols are the signs of the first and second time derivatives of the measurements. This report outlines how these symbols are used in diagnosis, considers several methods for estimating the symbols from measured data, and shows the behavior of the method we have chosen to use on measurements taken with our cooling system diagnosis testbed.

7 Pages

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