Synthèse d'observateurs pour les systèmes non linéaires - Application à la commande et au diagnostic des bioréacteurs

摘要

In this thesis, we first present a pilot process of a bioreactor where one is interested in the regulation ofdissolved oxygen levels consumed by biomass. This reactor is used for the validation of observers and controllaws proposed.In the context of observer synthesis, we consider a class of observable systems for any input. Firstly, we wereinterested in the case of system with discret measurements. A continuous-discret time observer is proposed and itis shown that the observation error exponentially converges to zero since the maximum sampling period remainsin a ball where the diameter is lower than a certain threshold. Secondly, we treated the case of system with anarbitrarily large output delay and we proposed a cascade observer to estimate the current state of the system.Exponential convergence of the error is guaranteed if the number of subsystems in the cascade is selected withsatisfaction to a certain condition. Two nonlinear control law particularly a high gain type and a backsteppingone have been proposed to control the dissolved oxygen levels in the bioreactor. As the control laws requireknowledge of the reaction rate which is not measurable, this variable was provided by the continuous-discrettime observer. Simulation results show the good performances of those control laws using the proposed observer.Those laws have been implemented on the pilot process allowing then a experimental validation of obtainedresults.