ISS Interval Observers for Nonlinear Systems Transformed Into Triangular Systems

International audienceDesigning an interval observer with stability properties for nonlinear systems, which are not cooperative and not globally Lipschitz, is an open problem. This paper studies a general canonical structure for which interval observers with input to state stability (ISS) properties can be derived. This canonical block triangular nonlinear structure is rather general and may result from a change of coordinates or an output injection. We provide a general method for explicitly constructing framers for systems for which can be given such a structure. We also construct ISS interval observers when additional properties are satisfied. The systems we consider are in general not cooperative and not globally Lipschitz. We illustrate the constructions by designing a framer and an ISS interval observer for two models of bioreactors. Copyright © 2012 John Wiley & Sons, Ltd