|by Lew Harris
Imagine a tiny insect-like robot that could be used to
explore a minefield or to support a small infantry unit by seeing over the next hill, an
age-old military problem.
Or picture the same "crawler" infiltrating a building seized by terrorists
holding hostages and feeding back video images and motion-sensing data showing exactly
where the terrorists and hostages were located.
Two Vanderbilt University mechanical engineering professors are developing just such a
device, a small robotic insect about a third the size of a credit card, which will have
applications for military and intelligence-gathering missions.
Professors Ephrahim Garcia and Michael Goldfarb were recently granted a three-year,
$904,000 contract to produce robotic insect crawlers. The contract was awarded by the
Defense Advanced Research Projects Agency (DARPA), a Pentagon organization.
They're also studying the feasibility of small flying robotic insects (microflyers)
under a $142,000 contract from the Central Intelligence Agency.
The challenges of developing and controlling a microflyer are more complex, but it
would be powered by the same technology as the crawlers, Garcia and Goldfarb said.
The two Vanderbilt researchers expect to produce a rudimentary prototype of the crawler
in the summer of 1998 and then refine it during the next two years. The crawlers would be
equipped with microelectromechanical systems (MEMS) for sensing their surroundings.
Garcia and Goldfarb plan to utilize "elasto-dynamic locomotion" to power the
insects, using piezoelectric actuators _ thin ceramic-coated metal plates that bend when
electricity is applied to them and snap back to original form when the power is off. It's
the same kind of technology that makes a pager vibrate.
The crawler would have a piezoelectric actuator that would make the body's two
lengthwise segments oscillate back and forth, Garcia said. One-piece legs attached to the
body would carry the insect forward. A space in the center of the body would contain the
power and the payload, which might be a microcamera or sensors that detect sound or heat.
Most previous robotic research has involved devices with multiple joints, each with its own motor or
actuator. But the Vanderbilt researchers believe that their use of piezoelectric actuators
is an advance over previous motor technology. "An electric motor is continuously
running," Garcia said. "If we use a vibratory system, we're exchanging kinetic
energy for potential energy. We're pulsing energy in as we need it."
Piezoelectric actuators are capable of turning more than 90 percent of electrical power
into movement, whereas an electric motor has an efficiency of about 60 percent, Garcia
For the flyer, engineers are borrowing from entomological research. Goldfarb said
scientists have discovered that an insect's wings flap five times faster than its brain
can command them to.
Scientists have also learned that insects use their muscles to flex their entire
exoskeletons, which are in effect resonating to keep the wings in motion, Goldfarb said.
The researchers have come up with a metal skeleton they believe will imitate the vibration
and magnify the movement of the piezoelectric actuators powering the wings.
Goldfarb and Garcia are also working on "swarm dynamics" _ the right
combination of crawling and flying bugs for conducting a search and interacting with the
The robotic insects will be so small and lightweight (about an ounce) that an
individual combat soldier could easily carry large numbers of them in addition to his
basic equipment. They will also be cheap and disposable.
Thousands of reconnaissance crawlers spread across the desert in the Persian Gulf War
could have made it impossible for Saddam Hussein's mobile SCUD missile launchers to get
away before U.S. bombers could find them, Garcia said. Although there is no range
requirement included in the DARPA contract, the Vanderbilt engineers hope to come up with
an insect with a range of more than half a mile.
Garcia and Goldfarb are also exploring the development of a small robotic insect that
would move with a hopping motion similar to that of a grasshopper. The ultimate robotic
insect, they say, would be one that could both crawl and fly.