Nonlinear speed estimation of a GPS-free UAV |
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Authors: | Giovanni L Santosuosso Khadidja Benzemrane |
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Affiliation: | 1. Dipartimento di Ingegneria Elettronica , Universitá di Roma Tor Vergata , Via del Politecnico 1, 00133 Rome, Italy;2. Laboratoire IBISC – CNRS/Université d'Evry Val d'Essonne , 40 rue du Pelvoux, 91020 Evry Cedex, France |
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Abstract: | In this article, the problem of robust state observer design for a class of unmanned aerial vehicles (UAVs) is addressed. A prototype four-rotors helicopter robot for indoors and outdoors applications is considered: the drone is not equipped with GPS related devices, so we describe a strategy to estimate its translational velocity vector based on acceleration, angles and angular speeds measurements only. Since the linearised system is non-observable at the equilibrium point, a nonlinear observability verification is performed for persistently exciting trajectories. A global exponential solution to this open problem is provided in the framework of adaptive observation theory when exact measurements are available. A modified observer is presented to enhance velocity estimation robustness in the realistic case of noisy measurements. The results are compared with a classical estimation strategy based on the extended Kalman filter to test the algorithm's performance. |
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Keywords: | nonlinear observability nonlinear observers adaptive observers |
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