Friday, January 20, 2012

One Per Cent - Speed limit for birds could mean better UAVs

Jacob Aron, technology reporter
(Image: Mark Hamblin/Oxford Scientific/Getty)

Fast-moving birds like goshawks can zip through dense forests by intuitively avoiding the trees, but researchers at MIT have discovered a theoretical speed limit over which they are guaranteed to crash. The findings could help build more efficient unmanned aerial vehicles (UAVs) by designing them to mimic bird flight paths.
UAVs are currently designed to fly at relatively slow speeds, allowing them to come to a halt before reaching the edge of their field of view. You might think that adding more sensors would allow them to fly faster, but MIT aerospace engineer Emilio Frazzoli says otherwise.
Frazzoli and colleagues created a mathematical model that shows a bird or drone flying through a built-up environment of a given density will always crash once it reaches a certain speed, no matter how much it knows about its surroundings.
The team believe that birds avoid this fate by gauging the density of their environment and adjusting their speed accordingly, knowing that they can always find a gap to fly through. This allows a bird to fly much faster than if it just relied on the limits of its vision. Frazzoli says that skiers use a similar strategy.
"When you go skiing off the path, you don't ski in a way that you can always stop before the first tree you see," he says. "You ski and you see an opening, and then you trust that once you go there, you'll be able to see another opening and keep going."
Frazzoli is now working with biologists at Harvard University to confirm whether his model matches the behaviour of real birds. His team is also designing a flying video game to test how well humans can navigate a simulated forest at high speeds, to see how close players can get to the theoretical limit predicted by the model.

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