Finite memory observer based method for failure detection in dynamic systems
Résumé
In the past decade, interest has been focused on the use of analytic redundancy for the Fault Detection and Isolation (FDI) (Frank, 1990; Gertler, 1991). Many applications in the FDI area use the state estimation technique to generate the accentuated fault functions, so-called residuals. Subsequent analysis of residuals may provide an information about a faulty component localisation. It is well known that infinite observer memory leads to the so-called divergence phenomenon caused by the model errors that observer tends to accumulate during its performance [Toda et al., 1978]. Moreover, the infinite memory inflicts observer insensitivity to recent measurements. This shortcoming brings us to the conclusion that an observer structure with finite memory would be more appropriate for the FDI. This paper presents extensions and improvements on the finite memory observer. The main contribution is to incorporate the parity relation design and observer into a diagnosis scheme and how to choose optimal length of the memory. The application of the finite memory observer to the sensor fault detection problem is illustrated by a numerical example. Simulation results show that the method is very effective for robust fault detection.