Birds display remarkable adaptability in harnessing their surroundings for efficient flight, exemplified by the ingenious behavior observed in Kestrels. These birds employ a unique technique known as wind-hovering or orographic soaring, where they skillfully maintain a stable position in the air without flapping their wings. This is achieved by exploiting orographic updrafts, created when the wind flows over obstacles. Kestrels significantly conserve energy by wind-hovering.
Inspired by the wind-hovering, researchers at MAVLab have been focusing on studying the autonomous orographic soaring of Micro Air Vehicles (MAVs). Our exploration and findings on this subject have been presented in papers at both ICRA 2023 and IROS 2023.
Autonomous Control for Orographic Soaring of Fixed-Wing UAVs
At ICRA 2023 in London, UK, MAVLab presented ‘Autonomous Control for Orographic Soaring of Fixed-Wing UAVs’. In this paper, we introduced zero excess updraft contour: the line in the wind field where the expected local updraft equates to the sink rate, and the target gradient line: a path in the wind field that has a gradient in available updraft.
A closed-loop pitch controller is devised to maintain the MAV’s position on the target gradient line using its single degree of control freedom.
The soaring location can be determined on the zero excess updraft contour by adjusting the target gradient line, specifically at the intersection of the target gradient line and zero excess updraft contour. Using the proposed method, autonomous soaring flight was demonstrated with a glider MAV in the wind tunnel.
AOSoar: Autonomous Orographic Soaring of a Micro Air Vehicle
At IROS 2023 in Detroit, USA, MABLab presented “AOSoar: Autonomous Orographic Soaring of a Micro Air Vehicle”. We demonstrated the autonomous orographic soaring of an MAV. A simulated-annealing-based search method was proposed to find soaring positions, and an Incremental Nonlinear Dynamic Inversion controller was devised for the soaring flight. In the wind tunnel test, we achieved successful wind-hovering flights without any priori knowledge of the wind field. Additionally, our verification process confirmed the MAV’s capability to adapt and find new soaring positions in response to changing updraft conditions using the proposed methods.
Autonomous Control for Orographic Soaring of Fixed-Wing UAVs Proceedings Article
In: Proceedings - ICRA 2023, pp. 5338–5344, Institute of Electrical and Electronics Engineers (IEEE), United States, 2023, (Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. ; 2023 IEEE International Conference on Robotics and Automation, ICRA 2023 ; Conference date: 29-05-2023 Through 02-06-2023).
AOSoar: Autonomous Orographic Soaring of a Micro Air Vehicle Proceedings Article