Fault diagnosis in nonlinear systems: An application to a three-tank system

The fault diagnosis problem for nonlinear systems is treated, some results based on a differential algebraic approach are used in order to determine fault diagnosability with the minimum number of measurements from the system. Two schemes of nonlinear observers are used for reconstructing the fault signals for comparison purposes, one of them being a reduced order observer and the other a sliding mode observer. The methodology was tested in a real time implementation of the three-tank system for which a previous identification of uncertain parameters is realized in order to improve fault estimations.