This clever flying robot can fly over, ride and turn as cleverly as a fruit fly.

Flying insects such as bees, dragonflies and fruit flies can achieve impressive aerodynamic feats, especially when they are trying to escape predators or the hitting movement of the human hand. Today, Dutch scientists have built a flying robot capable of performing similar maneuvers, although much larger than average insects, which could shed light on how these creatures perform these feats. Scientists have described their work in a new paper in Science.

There was a time when scientists believed that insect wings worked a lot like the wings of a plane. The upward and downward movement of their wings would generate lift because the air flowing on the wing follows its slightly inclined surface, while the downward flow lowers air pressure overhead. the wing, lifting it just enough to keep the body in the air. (This is a simplified and therefore incomplete explanation of the complicated aerodynamics of air transport based on the Bernoulli principle, but this will suffice for the purposes of this post.) But in the 1990s, a zoologist named Charles Ellington decided to test this theory. by putting various insects in the actual wind tunnels. The conventional lift that they measured was simply not enough to explain their ability to fly.

Subsequent research by Ellington has shown that a stable vortex tip is the most likely explanation of how insects stay at altitude. Once the vortex forms, it spirals out along the wing toward the tip, drawing air outward to prevent a stall. This explains how insects generate lift in the hover, but not how they manage to perform complicated maneuvers such as fast turns. This may be due to the way an insect wing can rotate to get rid of the whirlpool slightly, which allows the insect to change direction. But there is still a lot of mystery to explore. And it's here that this new flying robot comes in.

Matej Karasek, from the Delft University of Technology in the Netherlands, has long been intrigued by the agility of flying insects, using them as inspiration for developing tailless swing robots. "The main challenge was to design a wings actuation mechanism that would independently control body rotations around the body's three axes," he explains. And this mechanism had to be light enough for the robot to transport it. The theft of fruit flies provided the key. Karasek programmed his robot to imitate their hypothetical flight biomechanics.

It worked like a charm, and the result is the DelFly Nimble flying robot prototype. The wings of the robot beat 17 times per second, which generates an uplift and makes the robot able to control the direction of the flight with slight adjustments to the movement of the wings. It can move hovering in all directions (up, down, forward, backward and sideward), turn up and turn 360 degrees, such as loops or barrels. as the insect. It also offers excellent fuel efficiency, capable of hovering for five minutes or traveling more than one kilometer on a single charge.

"Unlike animal experiments, we totally controlled what was going on in the robot's" brain ", says Karasek. "This allowed us to identify and describe a new passive aerodynamic mechanism that helps flies … direct their direction throughout these fast turns."

It is therefore not necessary to have a feedback mechanism so that fruit flies can perform their avoidance maneuvers as quickly as possible.

"The robot has opened up new possibilities for studying insect flight," says Karasek. "But it's also a new type of flying robot with unique capabilities."

Insect-inspired drones have a lot of potential because they can fly more efficiently, with better maneuverability, than standard drones currently available. The DelFly Nimble is also relatively inexpensive to manufacture because it builds on existing manufacturing processes and uses standard components.

DO I: Science, 2018. 10.1126 / science.aat0350 (About DOIs).