Optimisation des phases de vol pour un drone capable de vol stationnaire et de vol en translation rapide

Les travaux présentés dans ce papier reprennent l'ensemble des aspects abordés lors de l'automatisation d'un système qui se veut être autonome : la modélisation, la linéarisation, la synthèse de loi de commande, la simulation, le pilotage, le guidage et l'optimisation. Le support expérimental est un micro-drone dont le domaine de vol est élargi(de la capacité de vol stationnaire "comme un hélicoptère" au vol d’avancement rapide "comme un avion"). Les points abordés ici sont plus particulièrement, la modélisation, la linéarisation, le pilote pour le vol stationnaire et le pilote longitudinal pour les transitions de phases de vol autonomes effectuées par séquencement de gains. Nous indiquerons également la structure du simulateur complet non linéaire qui permet de tester les lois réalisées avant de les embarquer. A la fin de l'article, les perspectives et la suite des travaux seront présentées

Development of a VTOL mini UAV for multi-tasking missions

Recent developments in the field of Mini-UAVs lead to successful designs in both hovering rotorcraft and fixed wing aircraft. However, a polyvalent MAV capable of stable hovering and fast forward flight is still expected. A promising candidate for such versatile missions consists of a tilt-body tail-sitter configuration. That concept is studied in this paper both from the flight mechanics and control points of view. Developments are based on an existing prototype called Vertigo. It consists of a tail sitter fixed-wing mini-UAV equipped with a contra-rotating pair of propellers in tractor configuration. A wind-tunnel campaign was carried out to extract experimental results from the Vertigo aerodynamic characteristics. A 6-component sting balance was fitted in the powered model enabling excursion in angles of attack and sideslip angles up to 90°. Thus, a detailed understanding of the transition mechanism could be obtained. An analytical model including propwash effects was derived from experimental results. The analytical model was used to compute stability modes for specific flight conditions. This allowed an appropriate design of the autopilot capable of stabilisation and control over the whole flight envelope. A gain sequencing technique was chosen to ensure stability while minimising control loop execution time. A MATLAB-based flight simulator including an analytical model for the propeller slipstream has been developed in order to test the validity of airborne control loops. Simulation results are presented in the paper including hover flight, forward flight and transitions. Flight tests lead to successful inbound and outbound transitions of the Vertigo

A robust multi-objective synthesis applied to launcher attitude control

We present in this paper an application of a multi-objective to the control of launcher during the atmospheric flight and at the maximal aerodynamic pressure point. This approach is based on the Cross Standard Form. The goal of this new method is to design control laws with high performances and robustness and to handle various kind of specification. Two principal methods encountered in the literature to solve this problem are either the LQG or H2 control and the Hinfinty method. The interest of our approach is that a non conventional LQG/LTR approach, required to satisfy the performance specification, can be integrated in a more general standard problem