Lightweight Perching Mechanisms for Flapping-wing Drones

While birds can perch with their feet and claws onto different terrains including a branch, drones can only land to a specific terrain, for example a runaway or a relatively flat clearance. To date, perching mechanisms are heavy and complex; they were mostly developed for quadcopters capable of carrying greater payloads. In comparison, flapping drones or ornithopters often belly land without perching appendages. Here, we proposed and evaluated three kinds of lightweight perching mechanisms in our laboratory, namely 1) an electro-adhesive patch, 2) dielectric elastomer fingers, and 3) a swinging hook. As the active perching mechanisms require high-voltage activation, they may not be as power efficient as they were thought. Instead, a swing hook comes in handy and consumes no power; it needs to be targeted to a branch by maneuvering the drone. Finally, we demonstrated a bat-inspired up-side down perching of a 60-gram X-winged flapping drone using a swinging hook.