Modelling and control of an buoyancy driven airship
Modélisation et Commande d’un Dirigeable Propulsé par la Force de Flottabilité
Résumé
A new concept of airship without thrust, elevator or rudder is considered in this thesis. It is actuated
by a moving mass and a mass-adjustable internal air bladder. This results into the motion of
the center of gravity and the change of the net lift. The development of this concept of airship is
motivated by energy saving. An eight degrees-of-freedom complete nonlinear mathematical model of
this airship is derived through the Newton-Euler approach. The interconnection between the airship’s
rigid body and the moveable mass is clearly presented. The dynamics in the longitudinal plane is analyzed
and controlled through a LQR method, an input-output feedback linearization, and the maximal
feedback linearization with internal stability. Thanks to maximal feedback linearization, an efficient
nonlinear control is derived. In this process, modelling, analysis, and control are solved for special
cases of the airship, which become gradually closer to the most general model. The most constrained
special case reduces to a two degree-of-freedom system. It is shown that the basic properties of this
two DOF mechanical system remain instrumental for the analysis and synthesis of advanced airship
models. These properties are far from being obvious from the most complex model. Through a singular
perturbation approach, the superposition of the two control actions in the longitudinal plane and
in the lateral plane is shown to achieve the control of the dynamics in three dimension.
Un nouveau concept de dirigeable est considéré dans cette thèse. Une commande non linéaire est mise en oeuvre, fondée sur la linéarisation maximale de la dynamique.
Domaines
Automatique
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