An output delay approach to fault estimation for sampled-data systems

The problem of fault estimation for a class of non-uniformly sampled-data systems is investigated from the time delay point of view in this paper. Firstly, the output delay approach is employed to model the sampled-data system as a continuous-time one with time-varying delay output. Then, based on the analysis of the inapplicability of the adaptive fault diagnosis observer in such class of time-delay systems, a novel augmented fault estimation observer design method is proposed to guarantee the exponential convergence of the estimation errors. Furthermore, an extension to the case of time varying fault estimation for the noisy sampled-data systems is studied. Finally, simulation results of a flight control system are presented to demonstrate the effectiveness of the proposed method.