New bird study has implications for robots & drones: researchers say

New bird study has implications for robots & drones: researchers say

At the time of lift off, birds’ wings generate tiny, circular currents of air known as wingtip vortices. A new study allowed a group of researchers to visualize and examine these wingtip vortices, and they discovered that found that the actual way the air moves is different from what is commonly thought based on theoretical calculations.

A team of researchers at Stanford University used four cameras to record a small parrotlet named Obi flying through laser. Stanford mechanical engineer David Lentink and graduate student Eric Gutierrez trained Obi in order to measure the vortices the bird creates during flight.

The study suggested that theoretical models commonly used to describe how birds lift off are not accurate.

Study co-author Diana Chin, a graduate student in the university’s Lentink lab, said, “The goal of our study was to compare very commonly used models in the literature to figure out how much lift a bird, or other flying animal, generates based off its wake.What we found was that all three models we tried out were very inaccurate because they make assumptions that aren't necessarily true.”

The study helped explain the way birds generate enough lift to fly. It also has implications for how flying next-generation robots and drones will be designed.

The researchers published their findings in the most recent edition (Dec. 6th) of the journal Bioinformatics & Biomimetics.

A report published by Wired added, "Understanding vortices - the air patterns created by a bird’s wings as it generates lift - is key to understanding flight and building better drones. There are already well-established models explaining flight and how bird’s support their weight, and a team from Standord wanted to test these by flying a bird called Obi through a laser sheet seeded with particles."

The research paper from Stanford University research team further informed....

For this experiment, Gutierrez, the study’s lead author and former graduate student in the Lentink lab, made parrotlet-sized goggles using lenses from human laser safety goggles, 3D-printed sockets and veterinary tape. The goggles also had reflective markers on the side so the researchers could track the bird’s velocity. Then he trained Obi to wear the goggles and to fly from perch to perch.

Once trained, the bird flew through a laser sheet that illuminated nontoxic, micron-sized aerosol particles. As the bird flew through the seeded laser sheet, its wing motion disturbed the particles to generate a detailed record of the vortices created by the flight.

Those particles swirling off Obi’s wingtips created the clearest picture to date of the wake left by a flying animal. Past measurements had been taken a few wingbeats behind the animal, and predicted that the animal-generated vortices remain relatively frozen over time, like airplane contrails before they dissipate. But the measurements in this work revealed that the bird’s tip vortices break up in a sudden dramatic fashion.

Gutierrez added, "Many people look at the results in the animal flight literature for understanding how robotic wings could be designed better. Now, we've shown that the equations that people have used are not as reliable as the community hoped they were. We need new studies, new methods to really inform this design process much more reliably."

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