Photo: NMEM/Science & Society
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Lucien
Bull demonstrates the high-speed
camera he invented in 1903, the first to record
insect flight.
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Despite the fact that we’d likely drown in our own
waste if it weren’t for their enormous fondness for
eating our garbage and excrement, flies don’t get any
respect. Not from most of us anyway, who see only pests
and disease vectors as we swat with abandon whenever
they’re around.
But there are a few good scientists and engineers who
reach for their notebooks and video cameras instead,
amazed and astounded by flies’ aeronautic wizardry. With
a brain that’s home to several hundred thousand
neurons—we each house 100 billion in ours—a fly can
duck, dive, hover, rotate, and fly with easy accuracy
and endurance, despite having a lousy field of vision
and a carb-based Dumpster diet for fuel.
One of the fly-enamored among us is Harvard
University’s Robert Wood, author of this issue’s “Fly,
Robot Fly,” in which he recounts efforts to build tiny
flying robots based on the fly’s native wing-flapping
skills. His own robotic fly, at 60 milligrams about the
size of a chubby real fly, is the first of this robot
class to become airborne.
The scientific study of insect flight has its roots in
the second half of the 19th century. Queen Victoria was
on the throne, technological innovation was in high
gear, and the Industrial Revolution careered along with
it. Natural history and flora and fauna worship were all
the rage—although they would soon give way to more
empirical disciplines like physics and science-based
medicine—and museums and societies sprang up to serve
this public interest.
Photography had also permeated the 19th-century
zeitgeist. British-born Eadweard J. Muybridge became the
first to isolate locomotion in his famous stop-action
studies of humans and animals. Meanwhile, in France,
physiologist, inventor, and chronophotographer
Étienne-Jules Marey, who discovered that insect wings
carve figure eights during movement, was inventing
cameras and devising experiments to tease out the
details of bird and insect flight. Some years later, his
assistant and successor Lucien Bull invented the
stereoscopic spark-drum camera, which took pictures at
up to 2000 frames per second. Bull used his invention to
make the first-ever movies of insect flight (go to
http://www.expo-marey.com/indexFR.htm
to see examples of their work).
Fast-forward to the late 20th century: the world went
digital and cameras and experimental methods improved
significantly, but questions about how flapping-wing
flight works at fly scales remained essentially wide open.
Then in the 1980s and ’90s, an eclectic and far-flung
cohort of researchers, among them Charles Ellington from
Cambridge University, Michael Dickinson, now at Caltech,
and Ronald Fearing from the University of California,
Berkeley, set out to describe the kinetics of insect
flight. Through ingenious experiments with live insects
and dynamically scaled-up insect models, they managed to
pin down some of the major mechanisms and physical
forces that propel a fly through its airspace.
Now the hope is to use that know-how to build better
houseflies: inexpensive, tiny robot flies that could
work together, lots of them, on search-and-rescue
missions, environmental monitoring, planetary
exploration, military surveillance, and in virtually any
situation in which it would be better or safer to send a
batch of robotic flies instead of humans.
Professor Wood’s accomplishment is remarkable, but
much remains to be done before you’ll see robotic flies
buzzing over a fire or monitoring tornado damage in your
neighborhood. Small doesn’t mean simple. The obstacles
facing tiny robots’ flying and working in uncontrolled
environments are as daunting as those faced by your pet
AIBO. But as is often noted, flies have had a hundred
million years or so to work out the kinks in their
evolutionary flight plans. Perhaps in another 10 we’ll
be able to say the same about their electronic counterparts.