Wednesday, April 12, 2006
Tiny Flyer Navigates Like Fly
April 11, 2006— An ultralight autonomous aircraft that mimics the navigational abilities of a fly could one day become a real fly on the wall.
The 10-gram microflyer, being developed by a team of researchers lead by Dario Floreano at the Swiss Federal Institute of Technology in Lausanne, has a 36-centimeter (14-inch) wingspan.
But it could one day be shrunk to insect size and used for search and rescue.
"A lot of groups are taking inspiration from insects but none of them have been able to reach that with an indoor flying system," said research scientist and project leader, Jean-Christophe Zufferey.
Autonomous indoor flight presents scientists with particular technological challenges that nature has already overcome.
"Indoor environments are really tough," said Erik Steltz, a PhD candidate in electrical engineering at the University of California, Berkeley. "There are so many things to bang off of I believe this is the best approach out there to do indoor guidance for aircraft."
For example, in order to zip around indoor obstacles — walls, corners, bookcases, furniture, ceilings, etc. — a flyer needs to see the objects and have the brain power to steer away.
On a more conventional robot, this typically requires powerful computing resources, high-resolution cameras, or some kind of distance sensor such as a laser range finder system.
But these components take up precious weight and the heavier an aircraft, the faster it must fly to stay aloft, making indoor navigation all the more challenging.
A fly navigates using its large, compound eyes, which let it see almost an entire field of view at once. Their optic lobes contain motion-sensitive neurons that respond to images moving across the retinas.
Those moving images, the so-called optic flow, combine data that the insect perceives as it flies straight, and data it senses from other motions such as turning, bobbing, or tilting side to side.
The visual data that comes as the insect is flying straight — for example, that a bookcase in its field of view is getting bigger — automatically contains information about the distance to that object.
In fact, flies tend to navigate in relatively straight lines until they get too close to an obstacle. Then they make a quick 90° turn away from the obstruction and continue flying straight again.
Flies also possess two organs, called halteres, which help them fly without flipping over.
Zufferey and his colleagues incorporated technology into their robot that mimics all of these things.
To mimic the fly's vision, the researchers installed two tiny, low-resolution cameras, one over each wing. A microchip-sized gyroscope keeps the microflyer stable.
Onboard signal processing and control software give the autonomous vehicle its insect-like behavior.
In their most recent experiment, the researchers tested the aircraft in a 7 x 7-meter (23 x 23-foot) room with walls painted in vertical strips of black and white.
The microflyer navigated on its own for nearly five minutes.
Zufferey and his colleagues are currently working to reduce the size of the aircraft to the size of a housefly and to give it the ability to adjust its altitude.
source:http://dsc.discovery.com/news/briefs/20060410/flybot_tec.html
