Design of exponential observers for nonlinear systems by embedding

For nonlinear systems in ?ⁿ which are observable but not uniformly, we study how to design explicitly exponential observers, after having the system immersed in ?^m with m>n. The central issue concerns the determination of a lipschitzian extension in ?^m of the dynamics, which is defined exclusively on a subset of empty interior. We propose some constructive tools and illustrate their utility on a biological example. Copyright © 2004 John Wiley & Sons, Ltd.