Stability analysis for unknown delayed systems controlled by model-free control

International audienceUnknown delayed systems are present in many domains and control this kind of systems remains a difficult problem. Indeed, we can find theses systems in physics, chemistry, aeronautics, etc. The main problem is that the delay is unknown, and so the model is not exactly well-known. By the way, the use of model-free control (MFC) remains a suitable solution to tackle this problem. This paper deals with a stability analysis to show the influence of a parameter on the stability of the systems regarding to the delay

Model-free control for unknown delayed systems

International audienceThe use of model-free control (MFC) spreads now more and more in industry. Nevertheless, control unknown delayed systems with this method remains an open problem. In this contribution, we present the use of model-free control in this context and we propose a solution to improve the effectiveness of this approach using a parameter estimation

Case Study - France, Sustainable Agriculture and Soil Conservation (SoCo Project)

This Technical Note 'Case Study ¿ France' is part of a series of case studies within the ¿Sustainable Agriculture and Soil Conservation¿ (SoCo) project. Ten case studies were carried out in Belgium, Bulgaria, the Czech Republic, Denmark, France, Germany, Greece, Italy, Spain and the United Kingdom between spring and summer 2008. The selection of case study areas was designed to capture differences in soil degradation processes, soil types, climatic conditions, farm structures and farming practices, institutional settings and policy priorities. A harmonised methodological approach was pursued in order to gather insights from a range of contrasting conditions over a geographically diverse area. The case studies were carried out by local experts to reflect the specificities of the selected case studies.JRC.DDG.J.5-Agriculture and Life Sciences in the Econom

Commande tolérante aux défauts et diagnostic des systèmes à retard inconnu par une approche sans modèle

In this thesis, the model-free control was applied and adapted to delayed systems whose delay is either known or unknown. This method of control does not require the specific knowledge of a model of the system, it finds all its effectiveness in the apprehension of the unknown delays. Different adaptations of the classical approach, based on the minimization of frequency and temporal criteria, have been proposed in the context of a known, bounded or unknown delay. They allowed us to extend the range of systems considered and to improve the intrinsic performance of the model-free control. The delayed systems, which are the main target of this thesis, were able to benefit from these improvements. The problem of the fault-diagnosis of delayed systems was then addressed. A new method of model-free diagnosis has been proposed, based on model-free control principles. Our proposal only uses the temporal evolution of the system's input and output signals. Due to the generation of residual signals, the detection and localization of actuator/system faults were permitted under certain assumptions. Finally, we have studied the fault-tolerance properties of model-free control and its efficacy has been proven. Compared with more conventional methods, such as the PI Controller for example, a notable difference is to be mentioned. Indeed, unlike a PI controller, the model-free control is robust not only to low-frequency input disturbance signals, but it also allows for the rejection of other signal types by estimating summary parameters. Throughout this report, the effectiveness of the proposed approaches was illustrated in terms of control or diagnosis by multiple academic examplesDans ce travail de thèse, la commande sans modèle a tout d'abord été appliquée et adaptée au cas des systèmes présentant un retard connu ou inconnu. Cette méthode de commande ne nécessitant pas la connaissance précise d'un modèle du système, elle trouve toute son efficacité dans l'appréhension de retards inconnus. Différentes adaptations de l'approche classique, reposant sur la minimisation de critères temporels et fréquentiels, ont été proposées suivant le contexte d'un retard connu, borné ou inconnu. Elles nous ont permis d'élargir le spectre des systèmes considérés et d'améliorer les performances intrinsèques de la commande sans modèle. Les systèmes retardés, qui sont la cible privilégiée de ce travail, ont pu bénéficier de ces améliorations. Le problème du diagnostic des systèmes à retard a ensuite été abordé. Une nouvelle méthode de diagnostic sans modèle a été proposée, fondée sur les principes mêmes de la commande sans modèle. Cette proposition s'appuie sur la seule évolution temporelle des signaux entrée/sortie du système. Par la génération de signaux résiduels, la détection et la localisation de défauts d'actionneurs et du système est assurée sous certaines hypothèses. Finalement, nous avons montré en quoi la commande sans modèle s'apparente à une commande tolérante aux défauts et son efficacité en tant que telle a été prouvée. Une différence importante est à souligner par comparaison à d'autres commandes plus classiques, de type PI par exemple. En effet, la commande sans modèle est non seulement robuste à des signaux perturbateurs basses fréquences en entrée, à l'identique d'une structure PI classique, mais elle permet également de rejeter d’autres types de signaux révélateurs de défauts via l’estimation de certains paramètres de synthèse. Tout au long du mémoire, l'efficacité des approches proposées en commande et en diagnostic est perçue au travers d'exemples académique

Fault tolerant control and diagnosis of unknown delayed systems by a model-free approach.

Dans ce travail de thèse, la commande sans modèle a tout d'abord été appliquée et adaptée au cas des systèmes présentant un retard connu ou inconnu. Cette méthode de commande ne nécessitant pas la connaissance précise d'un modèle du système, elle trouve toute son efficacité dans l'appréhension de retards inconnus. Différentes adaptations de l'approche classique, reposant sur la minimisation de critères temporels et fréquentiels, ont été proposées suivant le contexte d'un retard connu, borné ou inconnu. Elles nous ont permis d'élargir le spectre des systèmes considérés et d'améliorer les performances intrinsèques de la commande sans modèle. Les systèmes retardés, qui sont la cible privilégiée de ce travail, ont pu bénéficier de ces améliorations. Le problème du diagnostic des systèmes à retard a ensuite été abordé. Une nouvelle méthode de diagnostic sans modèle a été proposée, fondée sur les principes mêmes de la commande sans modèle. Cette proposition s'appuie sur la seule évolution temporelle des signaux entrée/sortie du système. Par la génération de signaux résiduels, la détection et la localisation de défauts d'actionneurs et du système est assurée sous certaines hypothèses. Finalement, nous avons montré en quoi la commande sans modèle s'apparente à une commande tolérante aux défauts et son efficacité en tant que telle a été prouvée. Une différence importante est à souligner par comparaison à d'autres commandes plus classiques, de type PI par exemple. En effet, la commande sans modèle est non seulement robuste à des signaux perturbateurs basses fréquences en entrée, à l'identique d'une structure PI classique, mais elle permet également de rejeter d’autres types de signaux révélateurs de défauts via l’estimation de certains paramètres de synthèse. Tout au long du mémoire, l'efficacité des approches proposées en commande et en diagnostic est perçue au travers d'exemples académiquesIn this thesis, the model-free control was applied and adapted to delayed systems whose delay is either known or unknown. This method of control does not require the specific knowledge of a model of the system, it finds all its effectiveness in the apprehension of the unknown delays. Different adaptations of the classical approach, based on the minimization of frequency and temporal criteria, have been proposed in the context of a known, bounded or unknown delay. They allowed us to extend the range of systems considered and to improve the intrinsic performance of the model-free control. The delayed systems, which are the main target of this thesis, were able to benefit from these improvements. The problem of the fault-diagnosis of delayed systems was then addressed. A new method of model-free diagnosis has been proposed, based on model-free control principles. Our proposal only uses the temporal evolution of the system's input and output signals. Due to the generation of residual signals, the detection and localization of actuator/system faults were permitted under certain assumptions. Finally, we have studied the fault-tolerance properties of model-free control and its efficacy has been proven. Compared with more conventional methods, such as the PI Controller for example, a notable difference is to be mentioned. Indeed, unlike a PI controller, the model-free control is robust not only to low-frequency input disturbance signals, but it also allows for the rejection of other signal types by estimating summary parameters. Throughout this report, the effectiveness of the proposed approaches was illustrated in terms of control or diagnosis by multiple academic example

Stability analysis for unknown delayed systems controlled by model-free control

International audienceUnknown delayed systems are present in many domains and control this kind of systems remains a difficult problem. Indeed, we can find theses systems in physics, chemistry, aeronautics, etc. The main problem is that the delay is unknown, and so the model is not exactly well-known. By the way, the use of model-free control (MFC) remains a suitable solution to tackle this problem. This paper deals with a stability analysis to show the influence of a parameter on the stability of the systems regarding to the delay

Stability analysis for unknown delayed systems controlled by model-free control

International audienceUnknown delayed systems are present in many domains and control this kind of systems remains a difficult problem. Indeed, we can find theses systems in physics, chemistry, aeronautics, etc. The main problem is that the delay is unknown, and so the model is not exactly well-known. By the way, the use of model-free control (MFC) remains a suitable solution to tackle this problem. This paper deals with a stability analysis to show the influence of a parameter on the stability of the systems regarding to the delay

Model-free control for unknown delayed systems

International audienceThe use of model-free control (MFC) spreads now more and more in industry. Nevertheless, control unknown delayed systems with this method remains an open problem. In this contribution, we present the use of model-free control in this context and we propose a solution to improve the effectiveness of this approach using a parameter estimation

Therapeutic approach and outcome of children with Philadelphia chromosome-positive acute lymphoblastic leukemia at first relapse in the era of tyrosine kinase inhibitors: An SFCE retrospective study

International audienceBackground Since the introduction of tyrosine kinase inhibitors (TKIs), the profile of pediatric relapse of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) has changed. However, the management of pediatric Ph+ ALL relapses is not currently standardized. Procedure We retrospectively analyzed the therapeutic strategies and outcomes of pediatric Ph+ ALL patients in first relapse who were initially treated with a TKI-containing regimen in one of the French pediatric hematology centers from 2004 to 2019. Results Twenty-seven children experienced a Ph+ ALL relapse: 24 (89%) had an overt relapse and three a molecular relapse. Eight involved the central nervous system. A second complete remission (CR2) was obtained for 26 patients (96%). Induction consisted of nonintensive chemotherapy for 13 patients (48%) and intensive chemotherapy for 14 (52%). Thirteen patients (48%) received consolidation. Allogenic hematopoietic stem cell transplantation (alloHSCT) was performed for 21 patients (78%). The TKI was changed for 23 patients (88%), mainly with dasatinib (n = 15). T315I was the most common mutation at relapse (4/7). The 4-year event-free survival and survival rates were 60.9% and 76.1%, respectively. Survival was positively associated with alloHSCT in CR2. Conclusion We show that pediatric first-relapse Ph+ ALL reinduces well with a second course of TKI exposure, despite the use of different therapeutic approaches. The main prognostic factor for survival was alloHSCT in CR2. Because of the small size of the cohort, we could not draw any conclusions about the respective impact of TKIs, but the predominance of the T315I mutation should encourage careful consideration of the TKI choice