Fault diagnosis for a class of nonlinear systems by means of a polynomial observer

This paper deals about the problem of fault diagnosis of a class of nonlinear systems using the theory of state observers. In order to reconstruct the faults of the system, a polynomial observer is proposed, which includes in its structure correction terms of high order. The methodology consists of add to the original system the faults as new states, which increase the order of the observer. This scheme reconstructs simultaneously faults and state variables. In addition, as a comparative study, it has been designed an observer of reduced order. Both techniques are applied to fault diagnosis of a three-tank system.