A H∞ approach to robust fault estimation of non-linear discrete-time systems

The paper deals with the problem of robust fault estimation of non-linear discrete-time systems. In particular, it is shown how to employ the unknown input observer approach and the H
_∞
strategy to design a robust fault estimation filter. The proposed approach is designed in such a way that a prescribed disturbance attenuation level is achieved with respect to the fault estimation error while guaranteeing the convergence of the observer. The resulting design procedure is relatively simple and boils down to solving a set of linear matrix inequalities, which can be efficiently achieved with modern computational packages. The final part of the paper presents an illustrative example which exhibits the performance of the proposed approach.