Curvature-Induced Buckling for Flapping-Wing Vehicles

This article explores a technique to leverage curved surfaces for producing preferential buckling that can be used to create forward thrust in flapping-wing devices. We present a novel concept for using anisotropically buckling beams in robot locomotion, facilitated via an analytical and finite-element-based analyses. We demonstrate that with symmetric flapping inputs from a motor, buckling beams can be used to generate forward thrust, power, and work while reducing the drag associated with the recovery phase of the flapping gait. Our analysis includes experimental data that measures the forces produced by wings flapping in air and water. The results show a clear difference in the work produced between buckling and nonbuckling curved beams and shows that the average force and work produced by buckling wings over a number of cycles with symmetric flapping is nonzero. This has been demonstrated on a new, two-fin swimming robot that, through the use of this phenomenon, is capable of reaching an average speed of 0.1 m/s. This article makes it possible for simple motor inputs to produce complex swimming gaits through careful consideration during the mechanical design phase for swimming robots.