State estimation for a class of uncertain nonlinear systems: a finite-time observer approach

In this paper, the problem of state estimation for a class of uncertain, and possibly unbounded, nonlinear systems is tackled. In order to deal with such a problem, a nonlinear observer is proposed based on a continuous homogeneous and Levant's nth order differentiators. The proposed nonlinear observer provides finite-time convergence and the observer synthesis is formulated in terms of some linear matrix inequalities (LMIs). Moreover, contrary to what the literature shows, the finite-time observer does not require any type of Bounded-Input Bounded-State (BIBS) condition. Some simulation results illustrate the effectiveness of the proposed finite-time observer applied to an unstable nonlinear system.