NONLINEAR OBSERVER FOR SWITCHED SYSTEMS: APPLICATION TO A BATCH BIOREACTOR OBSERVADOR NOLINEAL PARA SISTEMAS CONMUTADOS: APLICACI ´ ON A UN BIORREACTOR EN LOTE

The main objective of this work is to design a new state observer for a switched nonlinear system. The proposed observer contains a standard proportional term and a bounded feedback that improves the performance of the estimation process compared with other methodologies such as extended Luenberger-type observers. A theoretical analysis of the convergence of the proposed observer through an analysis of multiple Lyapunov functions is provided. The estimation strategy is applied to a bioreactor batch, where is performed a process of sulfate-reducing considering a hypothetical change in kinetic regime. The evolution of the reaction kinetics is described in three stages: the first stage is described by the Haldane-Boulton kinetic model; the second transitional stage called an interaction between the Haldane-Boulton and Moser-Boulton kinetic models; and the third stage is represented by the model Moser-Boulton. Sulfide concentration is considered as a measured variable of the bioreactor to implement the proposed observer. Numerical experiment results shown satisfactory performance of the considered methodology.