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TINY FLYING ROBOTS IN WORKS TO AID WAR, EXPLORATION EFFORTS
By Andrew Bridges
Associated Press / Sacramento Bee
Saturday, July 27, 2002
BERKELEY, Calif. (AP) - A team of researchers at the University of
California, Berkeley, hopes its invention will create a little buzz and a
lot of flap.
Engineers, biologists and others have spent four years developing a tiny
robot called the Micromechanical Flying Insect that - they hope - will one
day fly like a fly.
The project is among a handful aiming to engineer devices that can soar,
dart and hover on gossamer wings. The paths are different but the goal is
the same: to churn out tiny, nimble devices that can spy on enemy troops,
explore the surface of Mars or safely monitor dangerous chemical spills.
The Pentagon's Defense Advanced Research Projects Agency is funding much of
In recent years, scientists at Berkeley and elsewhere have made huge strides
in understanding the unsteady aerodynamics that allow insects and the
smallest of birds to fly. The challenge is to apply that knowledge to the
design of devices that - at least at Berkeley - mimic the size, weight,
power and, above all, aerodynamic elegance of a fly.
"What we're targeting is the blowfly, how it specs out," said Tim Sands, a
professor of materials science and engineering.
Lest anyone scoff, Sands and his colleagues point out that a fly can lift
its own weight, turn more quickly than any fighter jet, zip about even on
torn wings and cap it all off by landing on the ceiling.
"Insects," said Berkeley's Ron Fearing, "have tremendous maneuverability."
In a cluttered campus lab, the professor of electrical engineering and
computer sciences uses tweezers to pick up a prototype. The robot is a
flyweight contender for the title of most ambitious among the flapping
robots, generically called ornithopters, entomopters or micro air vehicles.
It has yet to fly.
The device is being developed under a five-year, roughly $2.5 million
contract. That's pricey for something best described in pocket-change terms.
It takes about a dime's worth of raw materials, including stainless steel
that must be folded under a microscope, to build one of the robots. A single
penny weighs more than two dozen of the devices. The wingspan is about the
diameter of a quarter.
Officials envision soldiers deploying the robotic insects to snoop in
"It takes an individual and extends their sensory capabilities -- like a
periscope -- but it flies independently," said Roy Kornbluh, an engineer at
SRI International in Menlo Park. The firm is helping to fund development at
the University of Toronto of a four-winged robot called "Mentor."
In February, the one-pound device became the first ornithopter to
successfully hover, doing so with the agility of a hummingbird. Mentor is
about one foot across but researchers hope eventually to shrink it to
hummingbird size and weight.
Researchers remain enchanted by flapping flight because it would make for
miniature flying machines that don't gobble large amounts of power.
"Flapping is much more aerodynamically efficient at small sizes, rather than
conventional aerodynamics," said Michael Dickinson, a professor of
integrative biology at Berkeley and a pioneer in understanding insect
But endowing a robot with enough smarts to control the flapping for
sustained flight remains difficult, if not impossible.
Consider the fruit fly, Dickinson said. It beats its wings 200 times a
second, flapping and rotating them in a complicated orchestration that
relies on three distinct mechanisms to provide lift.
The fruit fly can make a mid0-air U-turn in just eight strokes and 40
milliseconds. Fearing estimated that to copy that level of control, the
Berkeley bug would have about a three-stroke margin of error. Mistime the
fourth stroke, and the fly goes into a death spiral, he said.
"The good news is we know what the wings need to do. The bad news is we
don't know how to do it," Fearing said.
Robert Michelson, principal research engineer at the Georgia Institute of
Technology Research Institute, said it is too difficult to build a robot
that relies solely on modulating its flapping wings for stability and
control. The Mentor uses four tail-like fins to direct the downwash of its
wings to remain aloft.
Michelson said he is developing a flapping robot, called the entomopter,
that will use bursts of gas, a byproduct of the device's chemical propulsion
system, to adjust the amount of lift provided by each of the robot's twin
sets of wings.
"Until we can do things as well as you find them in creation, you have to go
to alternate techniques," Michelson said of his device, which NASA is eyeing
for use on Mars.
Michael Goldfarb, an associate professor of mechanical engineering at
Vanderbilt University, believes that limitations in battery and artificial
muscle technology will keep the tiniest ornithopters grounded.
Goldfarb's own efforts to build a flapping robot with a 6-inch wingspan were
"Our conclusion to that study was it's not doable with state-of-the-art
technology," he said.
As it works to get its fly to take wing, the Berkeley team acknowledges it
has set its sights high.
"It's a little bit of a moonshot," Dickinson said.
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