March 26, 2023

Flow-surface interactions offer unique opportunities to enhance the capabilities and efficiency of micro aerial vehicles (MAVs). The proximity of surfaces modifies the flow around the vehicle, which in turn alters the forces and moments acting on it. These so-called “proximity effects” include the well-known ground effect that benefits fixed-wing aircraft during takeoff and landing. For MAVs, additional opportunities arise from flying near walls and ceilings.

Our recent studies explore proximity effects for rotorcraft MAVs. In [1,2], we investigate “ceiling effects” for perching a small quadrotor on an overhang. The spinning propellers of a rotorcraft generate higher thrust near a ceiling, reducing power consumption. The study models and verifies this phenomenon for different propeller configurations, showing up to 3x power savings. A conceptual prototype demonstrates how to exploit ceiling effects for efficient perching maneuvers, highlighting potential for bimodal aerial-surface locomotion.

Like ceiling effects, wall effects offer opportunities for proximity-based enhancements of MAVs. Another study proposes “wall effects” for passive wall following of a ducted tilt-rotor MAV [3]. The aerodynamic interaction between the rotor wake and a vertical wall generates forces that stabilize the vehicle a fixed distance from the wall. By adjusting attitude and control gains, the stable distance can be tuned without position sensing. Flight experiments validate the ability to manipulate and eliminate the need for explicit wall sensing. The outcomes could enable vision-free navigation of corridors via human control.

Overall, these studies show how understanding flow-surface interactions offers new possibilities for MAVs. Proximity effects around ceilings, walls, and the ground could variously enable energy saving behaviors, simplified navigation, and expanded functional capabilities. Further work is needed to fully harness these opportunities, but early results highlight their promise for enhancing MAV performance through clever yet simple flow-surface coupling.

[1] Y. H. Hsiao and P. Chirarattananon, “Ceiling effects for surface locomotion of small rotorcraft,” in Intelligent Robots and Systems (IROS), 2018 IEEE/RSJ International Conference on, 2018, pp. 6214-6219.

[2] Y. H. Hsiao and P. Chirarattananon, “Ceiling effects for hybrid aerial-surface locomotion of small rotorcraft,” IEEE/ASME Transactions on Mechatronics, vol. 24, iss. 5, 2019.

[3] R. Ding, Y. H. Hsiao, H. Jia, S. Bai, and P. Chirarattananon, “Passive Wall Tracking for a Rotorcraft with Tilted and Ducted Propellers using Proximity Effects,” IEEE Robotics and Automation Letters, vol. 7, iss. 2, pp. 1581-1588, 2022.