Supplementary material from "An insect-inspired collapsible wing hinge dampens collision-induced body rotation rates in a microrobot"

Some flying insects frequently collide their wingtips with obstacles, and the next generation of insect-inspired micro air vehicles will inevitably face similar wing collision risks when they are deployed in real-world environments. Wasp wings feature a flexible resilin joint called a ‘costal break’ that allows the wingtip to reversibly collapse upon collision, helping to mitigate wing damage over repeated collisions. However, the costal break may provide additional benefits beyond reducing wing wear. We tested the hypothesis that a collapsible wing tip can also dampen sudden and unpredictable body rotations caused by collisions. We designed a wing buckle hinge for an insect-scale microrobot, inspired by the costal break in wasp wings, and performed wing collision tests in a yaw-based magnetic tether system. We found that a collapsible wing tip reduced collision-induced airframe yaw rates by approximately 40% compared to a stiff wing, and that the effect was most pronounced for collisions that occurred early in the wing stroke. Our results suggest that a collapsible wingtip may simplify flight control requirements in both insects and insect-scale microrobots. We also introduce a scalable hinge design for engineering applications that recreates the nonlinear strain-weakening behaviour of a costal break.