Autonomous Exploration of a Wind Field with a Gliding Aircraft

Soaring is the process of exploiting favorable wind conditions to extend flight duration. This paper presents an approach for simultaneously mapping and using a wind field for soaring with an unpowered aircraft. Previous research by the authors and others has addressed soaring in known wind fields. However, an adequate estimate of the wind field is required in order to generate energy-gain paths. Conversely, the exploration required to generate a useful map estimate requires energy. This work aims to address these problems simultaneously by attempting to maintain and improve a model-free wind map based on observations collected during the flight and to use the currently available map to generate energy-gain paths. Wind estimation is performed using Gaussian process regression. A path planner generates and selects paths based on energy efficiency and field exploration. The method is tested in simulation with wind fields consisting of single and multiple stationary thermal bubbles. The use of soaring flight with consistent improvement in map quality and accuracy is demonstrated in a number of scenarios.