As scientists in the Netherlands tried to figure out how to build a super-agile flying robot, they took inspiration from one of nature's most acrobatic flyers: The humble fruit fly.
And by building this robot, they've gained new insights into how the fly carries out one of its flashiest maneuvers.
The robot is called the DelFly Nimble. Its wingspan is about a foot wide. It has four wings that can beat at 17 times per second, which appear very delicate because they're made of the same material as space blankets.
Take a look at the DelFly Nimble in action:
Notably, it does not have a tail.
"The previous designs, they always had a tail, like a conventional airplane tail," said the robot's main designer Matěj Karásek. He's based at the Micro Air Vehicle Laboratory at Delft University of Technology in the Netherlands, and he and his colleagues released their findings on Thursday in Science.
In previous generations, he said, flapping wings propelled the robot forward while the tail helped to steer and stabilize it. The DelFly Nimble is completely controlled by the wings. "The challenge was actually integrate the control into the wing motion, and that's what we achieved," Karásek said.
The wings can each move individually or rotate around the center axis — the body of the robot — in order to maximize the machine's agility. It can either be controlled manually or the researchers can pre-program the maneuvers.
The robot can hover for about five minutes on a full battery, or fly for more than a kilometer, Karásek said.
And because the scientists built it and are controlling all the movements, they can use it to learn more about how fruit flies actually carry out their breakneck maneuvers. That caught the attention of biologists.
"When I first saw the robot flying, I was amazed at how closely its flight resembled that of insects, especially when maneuvering," experimental zoologist Florian Muijres of Wageningen University & Research said in a statement.
The researchers tried to get the robot to replicate how they think fruit flies move during what they call "high-agility escape manoeuvres, such as those used when we try to swat them."
And as they replicated what Karásek calls a "rapid banked turn," they noticed something interesting – a "new passive aerodynamic mechanism" that helps the fly steer. Basically, the fly is effectively turning around three different axes around the body as it quickly changes direction. But Karásek says they found that one of those three rotations happened passively, so they didn't actually need to program the robot to turn on that axis.
Karásek sees this type of robot carrying out all kinds of tasks in the future. They want to make them smaller, and more autonomous.
"As it is now, it can already carry a small camera that can send live video feed to the operator," he said. "Our goal is to make them aware of what is around them, able to avoid hitting obstacles or flying into humans, make them able to explore remote areas, fly through openings like windows and doors."
He said the long term vision is to have them working in a swarm to complete tasks, such as pollinating an entire greenhouse or completing a search and rescue operation.