Meeting Abstract
Sustained hovering is a special behavior that separates the aerodynamic flight techniques of hummingbirds from other birds. This remarkable behavior is aided by the relatively large supracoracoideus muscle allowing the upstroke to produce lift. The ratio of the upstroke versus downstroke lift force defines the symmetry of the wingbeat cycle. Some insects have the ability to invert the chamber of their wings during the upstroke to equally distribute the weight support throughout the wingbeat cycle. While hummingbirds do have stiff wings, they cannot invert the chamber of their wings to maximize their wingbeat symmetry. Previous works have inferred these forces indirectly through kinematics or flow measurements that ignored accelerations and volumetric gradients. To understand the varying weight support, we resolved the instantaneous force generated by a freely hovering hummingbird in vivo within a wingbeat directly. Our method is noninvasive and has been validated using independent force measurements on a quadcopter with pulsating thrust. The method is scalable for birds and robots across taxa.
