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Commande variante dans le temps pour le contrôle d'attitude de satellites

Alexandru-Razvan Luzi 1
1 LAAS-MAC - Équipe Méthodes et Algorithmes en Commande
LAAS - Laboratoire d'analyse et d'architecture des systèmes
Abstract : This manuscript considers time varying control, with a strong emphasis on a satellite application. Three types of control structures are studied : a switch-based approach, LPV control and direct adaptive control. In this last field we introduce new theoretical results which allow structuring the gain and the adaptation law. The results are validated in simulation and are currently tested on board a satellite. The application we consider is satellite attitude control using reaction wheels. Taking into account the inherent limitations of these actuators, we first point out the need to implement control laws that vary according to the operating conditions. In particular, one seeks controllers that guarantee a fast response when the pointing error is small, whilst limiting the control effort when the satellite is far from its reference position. Starting from the preliminary results concerning the switch-based control law currently implemented on the Myriade satellites, a first part of our work is dedicated to LPV control. A synthesis method is developed, which allows obtaining new control algorithms expressed within this framework. The proposed approach is based on the specification of the control objectives through an LPV reference model, describing the ideal closed-loop behaviour. The simulations carried out with LPV algorithms obtained by using this method show that they meet the needs of our application. Nonetheless, the choice of a reference model proves to be difficult. This obstacle has been surpassed by using direct adaptive control. In this approach, specifications regarding the behaviour at small and large pointing errors can be added through constraints on the laws defining the control gains adaptation. We thus introduce a new synthesis method, based on which structured adaptive control laws are obtained. The closed loop stability proofs are based on tools of the Lyapunov theory, specific to adaptive and robust control. This combination allows us to establish stability proofs for structured adaptive laws containing, for instance, the sigma-modification. Several laws obtained in this way have been tested on a complete simulator, based on a non-linear model of a satellite in its orbital environment. The results show the interest of such adaptive algorithms, which allow in particular to modify the satellite dynamics depending on the available capacity of the actuators. Based on these positive results, a fight-test campaign on the Picard satellite is underway.
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  • HAL Id : tel-01021457, version 1

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Alexandru-Razvan Luzi. Commande variante dans le temps pour le contrôle d'attitude de satellites. Automatique / Robotique. Institut Supérieur de l'Aéronautique et de l'Espace - ISAE, 2014. Français. ⟨tel-01021457⟩

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