抄録
Flapping-wing small flying robots inspired from natural flyers have a potential for high maneuverability and high aerodynamic performance in low-Reynolds-number flow regime. To generate sufficient aerodynamic force in hovering flight, the wings should not only flap but also feather (rotate around the spanwise direction) in order to maintain appropriate angle of attack. The feathering motion is typically realized by passive torsion of the wing film in conventional flapping-wing robots. Here we propose a new wing structure which utilizes the passive feathering more actively. A hinge part was inserted at the wingbase of the wing, allowing an overall feathering rotation rather than the torsion of the wing surface. We compared four types of hinges with different maximum feathering angle using a tethered single-wing flapping mechanism driven by an electric DC motor. The wing shape and flapping motion were similar to those of hummingbirds. As a result, both generated vertical force and power consumption decreased with the maximum feathering angle of the hinge. Efficiency represented as vertical force per power consumption, however, was maximized by choosing the hinge with small feathering angle, in this case, 10 degrees. These results suggest that aerodynamic efficiency can be optimized by utilizing passive feathering rotation at the wingbase, resulting in reduction of mass proportion of a battery.
