Abstract:

A nonlinear unknown input observer based fault detection method for some discrete time switched nonlinear systems is studied. Two kinds of nonlinear unknown input observers with different structures are proposed. For each observer, two kinds of switching signals which include arbitrary switching signal and switching signal with average dwell time are considered. Under the condition of arbitrary switching signal, switched Lyapunov function method is used for designing parameters of nonlinear unknown input observer; while under the condition of switching signal with average dwell time, multiple Lyapunov function method is employed for designing parameters of observer. All design conditions are formulated as linear matrix inequalities. Then, the proposed nonlinear unknown input observers are used to generate residuals for fault detection. A simulation example is given to verify the efficacy of the proposed fault detection method.