Aerial drones made a name for themselves dropping bombs in Afghanistan, but there’s hope they’ll soon serve a more benign purpose, providing same-hour delivery of toothpaste to impatient urban customers. In order for drones to safely navigate crowded city environments, though, technology will have to improve considerably and an engineer at Stanford has found inspiration for those advances in an unlikely place: the head movements of lovebirds.
Researchers in mechanical engineer David Lentink’s lab actually set out to study something else — the stunning ability of lovebirds to turn, quite literally, on a dime. But as they watched high-speed video footage of the birds in-flight, they noticed something even more striking, that while performing turns, the birds rotated their heads in amazingly fast bursts.
When a bird turns its head quickly, its vision becomes blurred, which leaves it vulnerable to collision. To minimize this disorientation without compromising agility, birds make what are called “saccades,” in which they turn their heads rapidly, hold steady just long enough to refocus their gaze, then turn their heads again. Each saccade occurs through about 60 degrees of rotation and birds can perform multiple saccades in a single second — a rate so fast that they never really experience the blurred interludes.
“Because the period in which their eyes shift is so short, the brain can actually ignore it,” says Lentink.
Even more impressively, the lovebirds — which hail from scrublands in Africa — are able to coordinate their saccades with other flight behaviors in a way that optimizes performance. The birds beat their wings 20 times per second; in the forward position, their wings very briefly cover their eyes. It’s in those precise moments, when their vision is obstructed by their wings anyway, that the birds perform the saccades.
“They overlay two things that impair vision,” says Lentink. “It makes sense to time a head saccade right then.”
As for drones, saccades could come in handy when making quick turns between apartment buildings. They would allow a drone camera to minimize the time when it’s out of focus, and could be timed to coincide with other moments when a drone’s vision is impaired — like right after it flies through the line of laundry you’ve hung out to dry.
Kevin Hartnett is a writer in South Carolina. He can be reached at firstname.lastname@example.org.