A fault detection methodology for discrete nonlinear polynomial systems

This paper proposes a fault detection observer for classes of nonlinear models which consist of bilinear and polynomial nonlinearities up to degree three and are structured in discrete state space form. The observer is designed such that the error dynamics are time-varying and independent of unknown distubances. Sufficient conditions are given, in an efficient compact form, for a robust fault detection observer to exist, to be robust with respect to unknown disturbances and to detect a certain class of faults. An illustrative example is given.