Insect-Inspired Drones: Adjusting the Flapping Kinetics of Insect-Inspired Wings Improves Aerodynamic Performance

Abstract

Insects flap their wings through a highly specialized musculoskeletal system that allows the wings to rotate about three degrees of freedom. Consequently, the wingtip trajectory is adjustable in 3D, and accompanied with appropriate wing feathering (wing pitch). Remarkably, the complex flapping motion is achieved by thoracic muscles acting on the wing hinge. The wings themselves do not possess muscles but adjust their shape and orientation by elastically deforming due to the loads applied on them during flapping. Previous attempts to develop insect-inspired flapping drones have mostly focused on simplified linear flapping mechanisms, which do not utilize the interaction between the wing flexibility and flapping kinematics to its full potential. Here, the aim is to improve flapping drones’ performance by introducing mechanisms that mimic insects’ flight. The first is an elastic beam mechanism, allowing the wing root to swing during flapping, and the second is a passive wing pitch mechanism that allows the wing to rotate at stroke reversals. The two mechanisms are tested using high-fidelity insect-inspired 3D-printed wings and show a sixfold improvement of aerodynamic performance compared to linear flapping kinetics of the same flexible wings. This underscores the necessity of bioinspired flapping mechanisms in future flapping drones.