A real-time fault diagnosis and parameter tracking scheme

A method for achieving the detection, isolation, and estimation of faults is presented. The systems considered are SISO systems represented by input-output models. Assuming that the model parameters are multilinear in the underlying (physical) parameters, the influence of each physical parameter on the model parameters (called the influence vector) can be interpreted as a fault template line associated with that physical parameter. The influence matrix is assumed to have been computed off-line at the nominal (fault-free) point, and stored for later use in online fault diagnosis. After a fault is detected, as indicated by a change in the identified models, the faulty physical parameter is first isolated and then estimated using the influence matrix. To avoid the use of persistently exciting test inputs required by the identification process in this parametric-model scheme, a nonparametric-model method is also developed based on the estimates of the impulse response of the system