Robust Control Design for a Flexible Unmanned Aerial Vehicle

This paper aims to derive a comprehensive dynamical model and analysis of a High-Altitude-Long-Endurance (HALE) Unmanned Aerial Vehicles (UAVs). Structure of such an aircraft needs to be lightweight and capable of carrying a substantial payload. For low drag, the aircraft must have high aspect ratio. Moreover, safety factors for these aircraft are not as high as those for manned aircraft. These imply that HALE UAVs are considerably more flexible than manned aircraft. Hence, in the dynamical analysis of such aircraft, a formulation unifying the elastic and rigid body motions of the aircraft must be used. A newly developed theory for the dynamics of maneuvering flexible aircraft is ideally suited for the analysis of such aircraft. The uniqueness of this paper lies in its nonlinear structural model. The equations of motion are obtained by means of the Lagrangian equations in quasicoordinates. A perturbation approach separates the problem into nominal dynamics and perturbation dynamics. The nominal dynamics are used to design desired maneuvers and to determine the corresponding structural deformations. The perturbation dynamics are used to address stability of the aircraft.