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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

Modélisation et contrôle d’un robot spatial flexible pour la capture d’un débris en rotation / Modeling and Control of a Flexible Space Robot to Capture a Tumbling Debris

Dubanchet, Vincent 14 October 2016 (has links)
Les débris en orbite sont actuellement une source de préoccupation majeure pour les acteurs du spatial et pour le reste de la population, comme en témoignent les articles de presse et les œuvres cinématographiques sur le sujet. En effet, la présence de ces objets menace directement les astronautes en mission et les satellites en opération. Parmi les nombreuses options déjà envisagées pour les traiter, cette thèse se concentre sur l’approche robotique, en proposant des outils et des méthodes de modélisation et de contrôle pour un satellite chasseur équipé d’un bras manipulateur. Des modèles dynamiques et des schémas de simulation optimisés sont ainsi développés pour tout système multi-corps constitué d’une base mobile supportant un nombre quelconque d’appendices rigides ou flexibles. Par la suite, les trajectoires de capture sont générées en conservant la continuité en accélération avec le mouvement naturel du point cible, dans le but de saisir aussi délicatement que possible le débris en rotation. Le suivi de cette trajectoire par l’effecteur du robot chasseur est alors assuré par une loi de contrôle à deux niveaux, dont le réglage repose sur la synthèse H1 structurée. Une étude de robustesse est également mise en place pour assurer la stabilité et les performances du système en boucle fermée, malgré les changements de configuration du bras. Enfin, la validation des travaux de thèse est réalisée par voie numérique avec un simulateur haute-fidélité, et par voie pratique avec un banc d’essais robotique incluant des composants physiques en temps réel. / On-orbit debris are currently causing deep concern for space agencies, related companies, and also among the population. ¿is is evidenced by the numerous scientific articles and recent movies on the matter. Indeed, these objects pose a serious threat for the astronauts on mission and for operational satellites. Among the various technical concepts already designed to address these threats, this thesis focuses on space robotics. Tools and methods are thus introduced for the modeling and control of a chaser satellite equipped with a manipulator. Dynamic models and optimized simulation schemes are developed to handle any multi-body system made up of amoving base embedding various appendages, either rigid or flexible. ¿en, a trajectory planner is designed to ensure acceleration continuity with the natural motion of the debris in order to perform a soft capture. ¿is reference trajectory is tracked by the end-effector of the chaser using a two-level control law, which is tuned by the structured H1 synthesis. A robustness analysis is also presented to assess the stability and the performances of the closed-loop system with respect to the motion of the robotic arm. Finally, the outcome of the thesis is validated by a twofold approach: by numerical means with a highfidelity simulator, and by practical ones with a robotic test bench including physical components in real time.
2

Webová aplikace pro výuku simulací v ns2 / Web Application for NS2 Training

Pavlosek, Václav January 2009 (has links)
There is information to my master's thesis which is called “Web application for NS2 training”. This application works after installation and its source codes are saved on applied CD. It is said about implement Network Simulator 2. It helps to realize simulation of nets and then author inserts information about them into web application. Registered web's visitor has possibility to insert project into application. The project contents information about simulation created in NS2. Web application can also visible detail of possible project which is approved of administrator. Then the visitor can sort projects, search entered expression or connect his contribution to discussion forum. Administrator can approve users projects in his part of application. It makes available for the others. He can also delete them from database. Theory about technologies which are used for implementation of this application. It is talked about web Apache server, database MySQL server and programmable PHP language. There is also mentioned information about security of web application included possible attacks on applications and their database. It is presented proposal of database which creates core of application. This proposal is depended on application requirements. Next chapters give to reader whole image about functionality of application. There are mentioned samples of final graphical image of application. This document also provides the shows of source codes for creating database tables.

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