3,430 research outputs found

    Identification par Modèle Non Entier pour la Poursuite Robuste de Trajectoire par Platitude

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    The general theme of the work enables to handle a system, from identification to robust control. Flatness principles tackle path planning unless knowing the system model, hence the system parameter identification necessity. The principal contribution of this thesis deals with system identification by non integer models and with robust path tracking by the use of flatness principles for fractional models.Chapter 1 recalls the definitions and properties of a fractional operator and also the various representation methods of a fractional system. The stability theorem is also brought to mind. Fractional polynomial and fractional polynomial matrix algebras are introduced for the extension of flatness principles for fractional systems.Chapter 2 is about non integer model identification. After a state of the art on system identification by non integer model, two contexts are considered: in presence of white noise and of colored noise. In each situation, two optimal (in variance and bias sense) estimators are put forward: one, when considering a known model structure with fixed differentiating orders, and another one by combining nonlinear programming technics for the optimization of coefficients and differentiating orders.Chapter 3 establishes the extension of flatness principles to fractional systems. Flatness of linear fractional systems are studied while considering different approaches such as transfer functions or pseudo-state-space representations with polynomial matrices. Path tracking robustness is ensured with CRONE control. Simulation examples display theoretical developments on flatness through thermal diffusion on a metallic rod.Finally, Chapter 4 is devoted to validate the contributions to system identification, to trajectory planning and to robust path tracking on a real fractional system: a metallic rod submitted to a heat flux.Les études menées permettent de prendre en main un système depuis l'identification jusqu'à la commande robuste des systèmes non entiers. Les principes de la platitude permettent de parvenir à la planification de trajectoire à condition de connaître le modèle du système, d'où l'intérêt de l'identification des paramètres du système.Les principaux travaux de cette thèse concernent l'identification de système par modèles non entiers, la génération et la poursuite robuste de trajectoire par l'application des principes de la platitude aux systèmes non entiers.Le chapitre 1 rappelle les définitions et propriétés de l'opérateur non entier ainsi que les diverses méthodes de représentation d'un système non entier. Le théorème de stabilité est également remémoré. Les algèbres sur les polynômes non entiers et sur les matrices polynômiales non entières sont introduites pour l'extension de la platitude aux systèmes non entiers.Le chapitre 2 porte sur l'identification par modèle non entier.Après un état de l'art sur les méthodes d'identification par modèle non entier, deux contextes sont étudiés : en présence de bruit blanc et en présence de bruit coloré. Dans chaque cas, deux estimateurs optimaux (sur la variance et le biais) sont proposés : l'un, en supposant une structure du modèle connue et d'ordres de dérivation fixés, et l'autre en combinant des techniques de programmation non linéaire qui optimise à la fois les coefficients et les ordres de dérivation.Le chapitre 3 établit l'extension des principes de la platitude aux systèmes non entiers.La platitude des systèmes non entiers linéaires en proposant différentes approches telles que les fonctions de transfert et la pseudo-représentation d'état par matrices polynômiales est étudiée. La robustesse du suivi de trajectoire est abordée par la commande CRONE. Des exemples de simulations illustrent les développements théoriques de la platitude au travers de la diffusion thermique sur un barreau métallique.Enfin, le chapitre 3 est consacré à la validation des contributions en identification, en planification de trajectoire et en poursuite robuste sur un système non entier réel : un barreau métallique est soumis à un flux de chaleur

    INFACT technology watch report

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    This research has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement nº 776487. Furthermore, some of the authors (B.J. and V.H.-S.) were supported by the Spanish Ministry of Science Innovation and Universities under the framework of the R&D project RTI2018-098966-B-I00.Summary: This report presents a bibliometric study on patents and scientific publications related to the following technologies involved in INFACT: airborne electromagnetic methods, airborne gravity gradiometry, airborne magnetometry and drone-borne hyperspectral imaging. A statistical analysis of the documents reveals the main players, technology trends and collaboration patterns via bibliometric techniques

    Open Home Networks: the TEAHA Approach

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    The current trend for home appliances is networking. Although more and more of these appliances are networked, there is not a standard way of interaction, which restrains the development of services for in-home networks. The lack of standardisation is partly due to a legacy of business interests; white goods, audio video equipment, security, and personal digital appliances all have a different background and have different business models. Rather than profound standardisation we propose secure seamless interworking of technologies, applications, and business interests. In this paper we present an architecture which is embedded in legacy technology. Our approach combines known design patterns, augments existing technology, and facilitates so-called business clusters. Further, we discuss a prototype implementation that integrates as an example OSGI, ZIGBEE, and UPNP technology with CECED (white goods) business interests. The work reported in this paper has been executed in an international industrial project: TEAHA

    Évitement d'obstacle dans un environnement 3D dynamique

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    Fractional modeling of wind speed turbulence

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    This paper proposes a method to design a wind turbulence model based on real wind spectral characteristics. It uses models based on Cole-Cole fractional functions to approximate the wind turbulence power spectral density. Von Kármán model is the most commonly used model but originally designed for aircraft in high altitude. Therefore, it is not suitable for systems operating at low altitude, hence the need for more accurate models in these specific conditions. Shaping filters issued from the fractional models are employed to generate realistic random wind speed turbulence from a random white noise input. Then, a grey box model is proposed from physical parameters such as the classic von Kármán ones (mean speed, turbulence intensity and length scale)

    considerações sobre a intervenção estatal no regime neoliberal

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    O presente trabalho tem por objetivo apresentar breves considerações sobre a intervenção estatal na cena contemporânea do modo de produção capitalista sob a égide do neoliberalismo, sendo o Estado, portanto, elemento indispensável e complementar ao modo de produção capitalista. O Estado no neoliberalismo assume um papel essencial na salvaguarda dos interesses do capital, por meio de um conjunto de medidas de austeridade, contrarreformas e de amplo ataque aos direitos conquistados historicamente por meio das lutas travadas pela classe trabalhadora. Acirrando e tensionando as expressões da “questão social”, portanto, as condições de pobreza e miséria da classe trabalhadora, bem como impondo duras derrotas e novos desafios para a cena atual das lutas de classes. O método utilizado nesta pesquisa fundamenta-se no materialismo histórico-dialético à luz da pesquisa de revisão bibliográfica. Assim, o trabalho se debruça, sem a pretensão de esgotar a discussão, sobre os desdobramentos impostos pela agenda neoliberal na contemporaneidade

    Sustainability in mineral exploration : exploring less invasive technologies via patent analysis

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    This paper presents a bibliometric study on patents and scientific publications related to airborne electromagnetic methods used as less invasive technologies in mineral exploration. A statistical analysis of the documents reveals the main players, technology trends, and collaboration patterns via bibliometric techniques. The article aims to analyse the gap between the model of sustainable less invasive innovations and the concrete implementation of the technology pull. Special attention is paid to the enablers of sustainable development and their presence in the technology landscape for less invasive exploration technologies.European Union's Horizon 2020 Programm

    Truncation of fractional derivative for online system identification

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    Fractional derivatives are non local operators that has compacity property in terms of parameter number for modeling diffusive phenomenon with very few parameters. One of its main properties is its non-local behavior, as it can be exploited to model long-memory phenomena such as heat transfers. However, such non-locality implies a constant knowledge of the full past of the function to be differentiated. In the context of real-time system identification, this may limit the experiences as calculations become slower as time progresses. This study deals with the relationship between frequency content of a signal and its truncation error in order to obtain real-time exploitable algorithms
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