Unknown Input and Measurement Noise Estimations for Switched Nonlinear Systems

The problem of unknown input and measurement noise estimations for a class of switched Lipschitz nonlinear systems is investigated in this paper. An augmented state is used to construct a new descriptor system to deal with the measurement noise in output vector, and then the descriptor system does not contain measurement noise in form. The main results are for the constructed descriptor system, a new Lyapunov-type precondition is developed in detail to present a sliding mode observer, which can estimate both the original system states and unknown inputs simultaneously. And the sliding model term is introduced to deal with the system nonlinearity and the unknown input. Finally, a simulation example of an electric circuit system is considered to show the effectiveness of the proposed methods.