How lasers and goggle-wearing parrots are helping flying robot designs

The Obi parrot wears goggles. Eric Gutierrez

A nearly invisible fog hangs in the air at a California laboratory, illuminated by lasers. A parrot flew through it, wearing a pair of small red goggles to protect its eyes.

When birds flap through water particles, their wings create destructive waves, and tracking patterns helps scientists understand how the animals fly.

In a new study, a team of scientists measured and analyzed particle trajectories produced by goggle-wearing parrots during test flights, showing that previous computer models of wing motion did not As precise as they imagined. The study's authors believe this new perspective on flight dynamics could inform future wing design for autonomous flying robots. [Bionics: 7 Clever Technologies Inspired by Nature]

When animals fly, they create an invisible "footprint" in the air, similar to the wake a swimmer leaves in the water. Computer models can account for these air disturbances and calculate the forces needed to keep the craft aloft and propel it forward.

A team of scientists recently developed a new system that tracks the airflow created by flight in unprecedented detail. They wanted to compare their improved observations with several commonly used computer models that use wake measurements to estimate the lift of flying animals to see if their predictions were on track, and the researchers turned to a Obi's Pacific parrot - a small parrot. Obi was trained to fly between two perches about 3 feet (1 meter) apart, through a mist of very fine water droplets illuminated by a laser sheet. Study author David Lentink, an assistant professor of mechanical engineering at Stanford University in California, said the airborne water particles are very small, "only 1 micron in diameter." (For comparison, the average length of human hair is about 100 microns thick.)

Obi’s eyes are protected from the laser by custom-made goggles: a 3D-printed frame that holds Lenses cut from human safety glasses - the same type of glasses that Longk and his team wear.

As the laser flashes - at a rate of 1,000 times per second - water droplets scatter the laser, and a high-speed camera captures 1,000 frames per second of Obi as he flies from one height to another. trajectories of disturbing particles. Patterns tracked in air particles allow scientists to track the wing's precise movements during flight. (Lentin Kabu, Stanford University)

The tests revealed something unexpected. Computer models predict that once the rotating air patterns, also known as vortices, are created by a bird's wings, they will remain relatively stable in the air. But the pattern Obi was tracking began to break down after the bird flapped its wings a few times.

"We were surprised to find that the swirls usually drawn in newspapers and textbooks, like beautiful donuts, suddenly burst after flapping two or three times," Lanting said in an email. told LiveScience. This means, he explains, that models widely used in animal flight studies that calculate lift based on the wake an animal generates may not be accurate.

"Thanks to the high-speed recording, we were able to capture it and play it back at slow speed, so we could see with our eyes how the vortex breaks up, making it difficult for models to predict lift well.

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The researchers used a device developed by Lentin's team in 2015 to make their own calculations of the Obi lift generated by the beating of its wings - A closed box containing a force sensor with high sensitivity capable of detecting vibration