Gust Energy Extraction for Mini and Micro Uninhabited Aerial Vehicles

This paper discusses energy extraction from atmospheric turbulence by small and micro uninhabited aerial vehicles. A nonlinear longitudinal dynamic model of a glider with elevators as the sole control input is used for the aircraft, and feedback control laws for energy extraction are discussed. An expression for energy change with respect to distance for flight in a spatially varying wind field is derived, and this is used with measurements of wind speed and gradient to compute the state that maximizes the instantaneous gain in total energy. A state feedback controller uses elevator input to regulate states to the optimal values. The state feedback control law is computed using linear quadratic regulator synthesis, and the state and input weight matrices that maximize energy gain are found using a search method. Simulation results of flights through sinusoidal gust fields and random thermal fields show the performance of the proposed approach.