Real-time optimal techniques for unmanned air vehicles fuel saving

Dynamic soaring can save fuel by the extraction of low-altitude wind shear energy. The problem of generating energy-saving trajectories in real time for an unmanned powered sailplane is considered. A method called 'inverse dynamics in the virtual domain' is investigated. The method results in rapid solution generation and is suitable for real-time applications. Three-dimensional unmanned aerial vehicle equations of motion and a non-linear wind gradient-model are used. Trajectories are generated to minimize the total power used per horizontal distance travelled for cross-wind travelling and in the total power used per total time in air for loitering mode. Trajectory following issues are addressed and an architecture for the control system is briefly described. A method for the estimation of wind shear gradient parameters is proposed. Validation is performed using a full six-degree-of-freedom model of a powered sailplane to verify the trajectory generation method.