APR 23, 2015 1:56 PM PDT

Bird Obstacle Avoidance Technique Could Help Drone Navigation

WRITTEN BY: Will Hector
Navigating a cluttered environment at high speed is among the greatest challenges in biology. Yet it's one virtually all birds achieve with ease.

It's a feat that David Williams is working to understand. A former postdoctoral fellow in the Harvard lab of Charles P. Lyman Professor of Biology Andrew Biewener, and now a postdoc at the University of Washington, Williams is the lead author of a study that shows birds use two highly stereotyped postures to avoid obstacles in flight.
A new study shows birds use two highly stereotyped postures to avoid obstacles in flight. The study could open the door to new ways to program drones and other unmanned aerial vehicles to avoid similar obstacles.
The study could open the door to new ways to program drones and other unmanned aerial vehicles to avoid similar obstacles. The study is described in a paper recently published in the Proceedings of the National Academy of Sciences.

"This was somewhat surprising to us," Williams said of the results. "In lower-order animals like insects, we think of these very stereotyped motor programs where you stimulate your muscle, and the passive dynamics of your exoskeleton or the tendons attached to that muscle control most of the motion.

"But when you look at higher-order animals, it's common to expect that those motor programs are going to be more complex, and there's going to be more subtle gradations in those programs. So it was surprising to see a very high-order animal like a bird using very simple motor programs. Biology is optimized to be just good enough to work, so what that indicates is those are very effective motor programs."

While most other research into bird flight has focused on what scientists call "clear-sky" flying, Williams' study was focused on understanding how, once birds identify gaps between obstacles -- whether those are buildings, cars, or trees -- they adjust their in-flight posture to squeeze through those spaces.

"A big part of biological motion is energy minimization and robustness," he explained. "You want to be able to get around without exhausting yourself, and if you do hit something, you don't want it to be something that's unrecoverable. You don't want to fall to the ground, or to break a wing."

The expectation, Williams said, was that birds would adopt a myriad of postures to allow them to fit between obstacles of varying sizes. The reality, however, was more interesting.

"What we actually found was there are two very distinct, stereotyped postures that are adopted," he said. "We thought there would be body rotation. We thought there might be intermediate stages where they would pull their wings in a little bit. We thought there would be stages where they might have one wing up and one down. We thought it would be catch-as-catch-can, and it's not."

In the first posture, what Williams calls "wings paused," the birds' wings are held wide out, at the top of the upswing of their flapping. In the second, the birds tuck their wings back against their bodies, almost as if they were perched on a branch.

"The paused posture ... interrupts their wing beat cycle for shorter periods of time, so they tend to lose less height, and their wings are ready to hit the air running, so to speak," Williams said. "We thought maybe they were using the ballistic posture in cases where they want to get smaller, but it doesn't actually make them much smaller from a forward angle. What it does do is reduce the amount they're going to rotate or be disrupted if they do collide with anything."

To understand the birds' in-flight postures, Williams and colleagues built a 20-meter-long flight corridor -- essentially an obstacle course consisting of a number of vertical poles -- for birds to fly through.

Researchers then fitted pigeons with small backpacks that powered a series of tiny, infrared LEDs, which were placed along the birds' backs, at their wingtips, near their wing joints, and on their heads. As the birds flew through the corridor, the LEDs were tracked by an array of five high-speed cameras, allowing researchers to determine their postures precisely.

Going forward, Williams said, researchers hope to expand the study to include horizontal obstacles similar to tree limbs. The findings in the current study may offer insight into how unmanned aerial vehicles could be programmed to avoid obstacles.

"When most people think about drones, they think about quad-copters ... people are getting better at controlling them through very narrow and complex obstacle courses, but there are experimental flight devices that feature adjustable wing-aspect ratios," Williams said. "This suggests that if we can build the brains into the material structure of an object, rather than into the computation controlling the object ... we can change the stability through that mechanism."

Follow Will Hector: @WriteCompassion

(Sources: Harvard; Science Daily)
About the Author
  • Will Hector practices psychotherapy at Heart in Balance Counseling Center in Oakland, California. He has substantial training in Attachment Theory, Hakomi Body-Centered Psychotherapy, Psycho-Physical Therapy, and Formative Psychology. To learn more about his practice, click here: http://www.heartinbalancetherapy.com/will-hector.html
You May Also Like
JAN 12, 2021
Technology
Artificial Intelligence Identifies Superspeed Insects
JAN 12, 2021
Artificial Intelligence Identifies Superspeed Insects
Artificial Intelligence (AI) are now being used by researchers to help identify insects with supernatural speed. Such te ...
FEB 02, 2021
Plants & Animals
The Vocal Dialects of Naked Mole Rats
FEB 02, 2021
The Vocal Dialects of Naked Mole Rats
Humans aren't the only creatures with dialects that are specific to certain regions. It seems that colonies of naked mol ...
MAR 07, 2021
Plants & Animals
What's Terroir and Does Whiskey Have It?
MAR 07, 2021
What's Terroir and Does Whiskey Have It?
Terroir is a term usually associated with wine; it describes the environmental characteristics like climate and soil tha ...
MAR 09, 2021
Microbiology
Dogs' Paws Are Cleaner Than Their Owners' Shoes
MAR 09, 2021
Dogs' Paws Are Cleaner Than Their Owners' Shoes
Assistance dogs are vital to many people who need them to perform daily tasks, but are sometimes denied entry to places ...
MAR 22, 2021
Clinical & Molecular DX
Good Dog! Man's Best Friend Sniffs Out Prostate Cancer.
MAR 22, 2021
Good Dog! Man's Best Friend Sniffs Out Prostate Cancer.
Trained dogs can spot aggressive prostate cancers by detecting trace amounts of chemical biomarkers in urine samples, sa ...
APR 07, 2021
Plants & Animals
Scientists Discover a Crab-Dissolving Parasite
APR 07, 2021
Scientists Discover a Crab-Dissolving Parasite
Parasites abound throughout the natural world. While not all of them cause the host's death, this newly discovered p ...
Loading Comments...