Abstract: The problem of the finite time functional observer design is investigated for a class of nonlinear systems, and the related results in literature are developed. First, an approach to design the asymptotic convergent functional observer is proposed for the nonlinear system. Second, based on the asymptotic convergent functional observer design, and combined with the theory of finite time observer, a new approach to design the finite time functional observer for the nonlinear systems is presented. It has been shown that, within any given time interval, the designed finite time functional observer realizes the accurate reconstruction of the function of the nonlinear system states. A simulation example is given to illustrate the correctness of the theoretical results.

Key words: finite time, functional observer, asymptotic convergence , nonlinear systems