Identification of quantifiers related to circadian rhythm variations

International audienceThe aim of this study is to propose quantifiers allowing to characterize the adaptation speed of the circadian rhythm of a living being based on temperature measurements. While the most commonly used model to represent circadian rhythm is the COSINOR model, it is not adapted to analyze changes. An extended COSINOR model is then proposed here in order to take into account temperature disturbances related to the activity of the studied living being. The quantifiers are obtained in a two step process. First, the extended COSINOR parameters are determined with a modified recursive least square algorithm, which is modified in order to compensate for the lack of persistent excitation. The estimates of these parameters are further filtered in order to provide several quantifiers which provide useful information on the adaptation speed of the studied living being. The proposed methodology is evaluated on rats temperature measurements obtained from a laboratory experiment

Synthèse dépendant de paramètres par optimisation LMI de dimension finie (application à la synthèse de correcteurs reréglables)

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Observability for any input: a canonical form for MIMO systems

International audienceA canonical form characterizing systems that are observable for any input is firstly proposed. Then, the synthesis of a high gain observer for these systems is detailed. The proposed class of systems is particularly composed by cascade subsystems where each subsystem is associated to a subset of the output variables and assumes a triangular dependence on its own state variables and may depend on the state variables of all other subsystems. The main contribution consists in extending the available results to allow more interconnections between the subsystems. Of fundamental interest, it is shown that he underlying observation error exponentially converges to zero in the absence of uncertainties. Moreover, the observation error can be made as small as desired by properly specifying the observer design parameter in the case where uncertainties are considered

Synthèse dépendant de paramètres par optimisation LMI de dimension finie (application à la synthèse de correcteurs reréglables)

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Identification of continuous-time linear systems with time-delay

International audienceThis paper addresses the identification problem of time-delay linear continuous-time systems. More specifically, the involved parameters and time-delay are jointly estimated using a suitable adaptive observer. The latter heavily borrows from the high gain observer design that has been widely investigated throughout the last decade. Global exponential convergence of the parameters and time delay estimates to their trues values is established under an appropriate persistent excitation property. The performance of the proposed identification approach is demonstrated by a simulation study involving an academic example

On output feedback control of non linear systems

International audienc

Sur la conduite de réacteurs chimiques

Les réacteurs chimiques sont considérablement utilisés dans les industries chimiques et pharmaceutiques. Le problème d asservissement de température associé est crucial aussi bien du point de vue de la qualité des produits que du point de vue de la reproductibilité des opérations. Cette thèse présente une approche de synthèse des asservissements de température pour les réacteurs chimiques exothermiques opérant en mode batch. Deux aspects de ce travail méritent d être mentionnés. Le premier consiste en un contexte de synthèse ingénieux. La synthèse est basée sur plusieurs techniques de commande issues des concepts de prédiction, de linéarisation par rétroaction, de modes glissants, de backstepping et de grand gain. Une action intégrale filtrée est incorporée dans la synthèse pour des considérations de précision et d insensibilité par rapport aux bruits de mesure. Le second aspect consiste en un observateur du type grand gain qui permet de réaliser une estimation précise de la chaleur de réaction en vue d affiner les performances des systèmes de commandes. Une illustration des performances de l approche de conduite proposé a été faite dans un environnement de simulation réaliste par rapport à la problématique considérée.Chemical reactors are extensively used in chemical and pharmaceutical industries. The underlying temperature control has shown to be of fundamental importance from product quality and process reproductibility points of view. This thesis presents a control approach to deal with the temperature servo problem in exothermic stirred tank batch reactors. Two features of this research work are worth to be emphasized. The first one consists in an engineering design framework for the control. The underlying design can be performed using various control techniques that heavily borrows from the concepts of prediction, state feedback linearization, sliding mode, backstepping and the high gain. A filtered integral action is incorporated into the design for free offset performance and noise measurements insensitivity considerations. The second one consists in likely high gain observer to perform an accurate estimation of the reaction heat to alleviate the control system performances. The performances the proposed approach are illustrated in a realistic simulation framework with respect to the problem under consideration.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Continuous-discrete time observers for a class of MIMO nonlinear systems

International audienceThe observer design problem for nonlineardynamical systems has received a remarkable attention over thelast four decades. A considerable effort has been devoted to theobserver design for systems that are observable for any inputusing the high gain concept for exponential convergence purposes.It is however worth mentioning that the available results aremainly devoted to the continuous-time measurements case in spiteof some nice contributions concerning the sampled measurementscase. The motivation of this talk consists in addressing theproblem of redesigning a high gain continuous-time observer for aclass of MIMO nonlinear systems that are observable for any inputin the case of non uniformly sampled measurements. This provides ahigh gain continuous-discrete time observer witch is more suitablefrom an engineering practice point of view. Two design features ofthe proposed continuous-discrete time observer are worth to bepointed out. Firstly, the observer is particularly described by aset of differential equations with instantaneous state impulsescorresponding to the measured samples and their estimates and ishence an impulsive system in nature. Secondly, the involvedobserver gain is time-varying and its calibration is achievedthroughout the tuning of two design parameters. A particularemphasis in put on the exponential convergence of the observerprovided that the sampling process is not too fast in a welldefined sense. Moreover, a suitable interpretation of the proposedcontinuous-discrete time observer is given, namely it is shownthat the underlying impulsive system can be put under the form ofa hybrid system witch is synthesized using a continuous-timedesign with an inter sample output predictor. The effectiveness ofthe proposed continuous-discrete time observer is emphasizedthroughout simulation results involving useful observer designproblems