We have developed a new, highly agile flapping-wing robot, called the DelFly Nimble. It can mimic high-speed insect escape maneuvers so accurately, that it exhibited very similar motion as fruitflies when performing these same maneuvers.
Interestingly, the robot turned around an axis that was not controlled during the escape maneuver. In particular, it would turn towards the flight direction. A fruit fly does the same, but it was not clear if it did this on purpose or not. Namely, it is not possible to look inside such an insect’s brain during flight. For the robot, however, we know exactly what happens inside its brain. We completely determine its control system and can log all its senses and motor actions during flight.
We found that the turn is due to an aerodynamic mechanism. When flying faster, the moments around the roll and pitch axis of the robot start to become coupled with the yaw axis. We modeled this effect, and the predictions of the model nicely capture the robot and fruitfly data.
The article can be found here: A tailless aerial robotic flapper reveals that flies use torque coupling in rapid banked turns, by Matěj Karásek, Florian T. Muijres, Christophe De Wagter, Bart D. W. Remes, and Guido C. H. E. de Croon, in Science, 14 Sep 2018, Vol. 361, Issue 6407, pp. 1089-1094.
Applications
We think that this new robot is an important step towards real-world applications of flapping wing robots. The previous DelFly versions were very sensitive to wind gusts or even strong drafts, such as from a zealous air conditioning system. These older designs had airplane-like tails for steering, which was not sufficient in such situations. Steering with the wings is a solution to this problem.
Given the light weight of flapping wing robots as the DelFly Nimble (weighing 29 grams), they are very safe for flight in indoor spaces and around humans. Applications may include having them fly in greenhouses for monitoring crop or in warehouses for checking stock.
See our press release here.