Pflimlin, Jean-MichelSoueres, PhilippeHamel, TarekMahony, Robert2015-12-07September9783902661166http://hdl.handle.net/1885/22895This paper describes a control strategy to stabilize the position of a Vertical Takeoff and Landing (VTOL) Unmanned Aerial Vehicle (UAV) in crosswind. The proposed approach takes advantage of the cascade structure of the system to design a hierarchical controller involving a High Level Controller devoted to position control and a Low Level Controller devoted to attitude stabilization. Both controllers are designed by means of backstepping techniques that allow the stabilization of the vehicle's position while on-line estimation of the unknown aerodynamic forces. Simulations as well as experimental results are presented to illustrate the concept.Keywords: Aerodynamic forces; Attitude stabilization; Backstepping technique; Cascade structures; Control strategies; Ducted fan; Hierarchical controllers; High level controllers; Low-level controllers; On-line estimation; Vertical take-off and landings; VTOL UAV; Attitude control; Ducted fan; Position control; VTOL UAV20062016-02-24