Lovebirds’ aerial antics could inform flying bot design
Image credit: Dreamstime
Stanford University researchers have studied how birds navigate in environments with limited visibility, with implications for the design of autonomous aerial vehicles.
Birds are capable of navigating through difficult conditions – such as in the dark and in stormy weather – which pilots require sophisticated technology in order to cope with. In order to understand how birds can handle these conditions, a group of mechanical engineers at Stanford analysed the flight of birds under different conditions in the first study of its kind.
The researchers, led by Professor David Lentink, watched as lovebirds flew through a crosswind tunnel with customisable wind and light settings. Lovebirds are small parrots native to Africa and popular as companion parrots and known for their affectionate behaviour.
The study found that the birds can navigate all windy environments equally well, whether in bright conditions or cave-like environments where the only visual beacon is a faint point of light. This contradicts the decades-long theory that birds require rich visual information in order to navigate.
“It’s amazing that lovebirds navigated 45-degree crosswinds even in our cave environment, because in their natural environment they fly in open habitats during the day,” said Professor Daniel Quinn, who is now a researcher at the University of Virginia. “Even well-trained pilots rely on runway lighting, radio beacons and guidance from air traffic controllers to land safely on windy nights.
“The conditions we studied can cause spatial disorientation in pilots, yet the lovebirds aced their manoeuvres in the dark as if there was no challenge. This was a big surprise to the entire team because we studied ‘naïve’ lovebirds; they were bred and kept in an indoor cage and had no experience with flying in the wind. Their ability may thus well be innate.”
The lovebirds were able to navigate by stabilising and fixing their gaze on their destination while yawing (twisting) their bodies into the powerful crosswind, contorting their necks by 30 degrees or more in order to stay on course. Based on these observations, the researchers built a computer simulation which suggested that the birds twist their bodies passively and their necks actively. A test using a simple mechanical bird model in the wind tunnel confirmed these findings.
According to Lentink, while aeroplanes have vertical tails to stabilise when travelling through wind, birds stabilise by passively orienting into the wind “like a weathervane” as their wings flap. Meanwhile, they actively twist their necks in order to direct their flight towards their destination.
The researchers hope that their findings could inspire more robust and computationally efficient visual control algorithms, which could prove useful for autonomous aerial robots: “The way lovebirds glean wind orientation may thus inform minimal control algorithms that enable aerial robots to manoeuvre in similar windy and dark environments.”
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