A Bivalued Observer for a Class of Uncertain Reactors

In order to design an observer for a dynamical system it is usually required that the model of the process is observable, or at least detectable. However, in some cases, in particular when unknown uncertainties are present, none of these properties is available. We would be tempted to give up the possibility of constructing an observer. However, in certain situations a multivalued observer, an observer giving multiple possible values of the state can be a reasonable alternative. In this paper we will analyze a realistic reactor model for which this situation is met: the process is unobservable and undetectable but a bivalued observer can be designed that provides a very satisfactory solution to the estimation problem.