In this paper, we consider two kinds of sampled-data observer design for a class of nonlinear systems. The system output is sampled and transmitted under two kinds of truncations. Firstly, we present definitions of the truncations and the globally uniformly ultimately bounded observer, respectively. Then, two kinds of observers are proposed by using the delayed measurements with these two truncations, respectively. The observers are hybrid in essence. For the first kind of observers, by constructing a Lyapunov-Krasovskii functional, sufficient conditions of globally uniformly ultimately bounded of the estimation errors are derived, and the maximum allowable sampling period and the maximum delay are also given. For the second ones, sufficient conditions are also given to ensure that the estimation errors are globally uniformly ultimately bounded. Finally, an example is provided to illustrate the design methods.
nonlinear systems, continuous observers, sampled output, delayed measurements