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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Fault tolerant control based on set-theoretic methods.

Stoican, Florin 06 October 2011 (has links) (PDF)
The scope of the thesis is the analysis and design of fault tolerant control (FTC) schemes through the use of set-theoretic methods. In the framework of multisensor schemes, the faults appearance and the modalities to accurately detect them are investigated as well as the design of control laws which assure the closed-loop stability. By using invariant/contractive sets to describe the residual signals, a fault detection and isolation (FDI) mechanism with reduced computational demands is implemented based on set-separation. A dual mechanism, implemented by a recovery block, which certificates previously fault-affected sensors is also studied. From a broader theoretical perspective, we point to the conditions which allow the inclusion of {FDI} objectives in the control law design. This leads to static feedback gains synthesis by means of numerically attractive optimization problems. Depending on the parameters selected for tuning, is shown that the FTC design can be completed by a reference governor or a predictive control scheme which adapts the state trajectory and the feedback control action in order to assure {FDI}. When necessary, the specific issues originated by the use of set-theoretic methods are detailed and various improvements are proposed towards: invariant set construction, mixed integer programming (MIP), stability for switched systems (dwell-time notions).
2

Fault tolerant control based on set-theoretic methods. / Commande tolérante aux défauts fondée sur des méthodes ensemblistes

Stoican, Florin 06 October 2011 (has links)
La thèse est dédiée à l'analyse et à la conception de la commande tolérante aux défauts (fault tolerant control - FTC) en se fondant sur des méthodes ensemblistes. Nous étudions l'apparition des défauts pour les systèmes multi-capteurs, et les modes de détection, ainsi que la conception de lois de commande qui assurent la stabilité en boucle fermée. L'utilisation des ensembles invariants/contractifs permet la caractérisation des signaux résiduels, qui sont utilisés par la suite dans le processus de détection et d'isolement des défauts. La décision est fondée sur le positionnement par rapport à des hyperplans de séparation avec des importantes réductions de temps de calcul. Un mécanisme dual mis en œuvre par un bloc de récupération, permet la certification de la récupération des capteurs précédemment affectés par ces défauts.Dans une perspective théorique, nous soulignons les conditions qui permettent l'inclusion du bloc FDI (fault detection and isolation) et sa raison d'être dans la conception des lois de commande. Cela conduit par exemple à la synthèse des gains de retour d'état statique, par résolution de problèmes d'optimisation efficace (linéaire/convexe).Selon les paramètres choisis pour le réglage, la conception de la FTC peut être complétée par un superviseur de référence ou d'une loi de commande prédictive, qui adapte la trajectoire d'état et l'action de commande par retour d'état, afin d'assurer l'identification et la détection des défauts. Les questions spécifiques à l'utilisation de méthodes ensemblistes sont détaillées et des améliorations diverses sont proposées, par exemple : la construction des ensembles invariants, des formulations moins complexes des problèmes de type Mixed Integer Programming (MIP), l'analyse de la stabilité des systèmes commutés (notion de ``dwell-time''). / The scope of the thesis is the analysis and design of fault tolerant control (FTC) schemes through the use of set-theoretic methods. In the framework of multisensor schemes, the faults appearance and the modalities to accurately detect them are investigated as well as the design of control laws which assure the closed-loop stability. By using invariant/contractive sets to describe the residual signals, a fault detection and isolation (FDI) mechanism with reduced computational demands is implemented based on set-separation. A dual mechanism, implemented by a recovery block, which certificates previously fault-affected sensors is also studied. From a broader theoretical perspective, we point to the conditions which allow the inclusion of {FDI} objectives in the control law design. This leads to static feedback gains synthesis by means of numerically attractive optimization problems. Depending on the parameters selected for tuning, is shown that the FTC design can be completed by a reference governor or a predictive control scheme which adapts the state trajectory and the feedback control action in order to assure {FDI}. When necessary, the specific issues originated by the use of set-theoretic methods are detailed and various improvements are proposed towards: invariant set construction, mixed integer programming (MIP), stability for switched systems (dwell-time notions).

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