Sampled-data observer design for nonlinear autonomous systems

Sampled-data observers are designed for nonlinear autonomous systems. The design is decomposed into two steps. First, a feedback term, which measures the state estimation error, is designed based on the Euler approximations of the systems. Second, a more accurate system model is used to estimate state with the obtained feedback term. Sufficient conditions are provided to guarantee the proposed observers are semi-globally practically stable. Compared with earlier results, these conditions relax the assumption in the literature that a globally Lipschitz Lyapunov function is given.