If you were designing a flying robot and you didn't want it to break every time you set it loose in an obstruction-filled environment, you could fill it with avoidance sensors to keep it from crashing.
Or you could design it with no sensors whatsoever and let it blunder its way from obstacle to obstacle.
Adrien Briod and Mariusz Kornatowski from Ecole Polytechnique Fédérale de Lausanne chose the latter tactic, taking inspiration from insects like bumblebees and carpenter beetles.
Their 'Gimball' robot contains only a gyroscopic stabilization system, a compass and an altitude sensor within a carbon-fiber ring.
You can see the result below: