FLIFO: A Passively Morphing Drone for Small Gap Traversal

Drones that can morph their shape are used to sidestep a design trade-off when the traversal of small gaps is required. Typically, small drones that are able to fit through small gaps are less efficient than larger drones that can't fit through the same gaps. Morphing drones combine both advantages by being big and efficient in their normal configuration, and by temporarily becoming small and inefficient in their morphed configuration. The here presented FLIFO (flip + fold) morphing drone manages to shrink to half its width, while maintaining full controllability. It does so purely passively, without requiring any additional actuators beside the ones needed for flight. This is an unprecedented accomplishment in morphing drones. Concretely, FLIFO's design consists of four simple hinges placed in a particular orientation on each arm, that cause the morphing once the drone flips up-side-down. Test flights of a prototype have successfully shown that this design can transition robustly between configurations while remaining in a tightly confined space, barely larger than the drone itself.