If the sight of a skittering bug makes you squirm, you may want to look
away — a new insect-sized robot created by researchers at the University of
California, Berkeley, can scurry across the floor at nearly the speed of a
darting cockroach.
And it’s nearly as hardy as a cockroach, too. Try to squash this robot
under your foot, and more than likely, it will just keep going.
“Most of the robots at this particular small scale are very fragile. If you
step on them, you pretty much destroy the robot,” said Liwei Lin, a professor
of mechanical engineering at UC Berkeley and senior author of a new study that
describes the robot. “We found that if we put weight on our robot, it still
more or less functions.”
Small, durable robots like these could be advantageous in search and rescue
missions, squeezing and squishing into places where dogs or humans can’t fit,
or where it may be too dangerous for them to go.
“For example, if an earthquake happens, it’s very hard for the big
machines, or the big dogs, to find life underneath debris, so that’s why we
need a small-sized robot that is agile and robust,” said Yichuan Wu, first
author of the paper, who completed the work as a graduate student in mechanical
engineering at UC Berkeley through the Tsinghua-Berkeley Shenzhen Institute
partnership. Wu is now an assistant professor at the University of Electronic
Science and Technology of China.
The study appears today (Wednesday, July 31) in the journal Science Robotics.
The robot, which is about the size of a large postage stamp, is made of a
thin sheet of a piezoelectric material called polyvinylidene fluoride, or PVDF.
Piezoelectric materials are unique, in that applying electric voltage to them
causes the materials to expand or contract.
The researchers coated the PVDF in a layer of an elastic polymer, which
causes the entire sheet to bend, instead of to expand or contract. They then
added a front leg so that, as the material bends and straightens under an
electric field, the oscillations propel the device forward in a “leapfrogging”
motion.
The resulting robot may be simple to look at, but it has some remarkable abilities.
It can sail along the ground at a speed of 20 body lengths per second, a rate
comparable to that of a cockroach and reported to be the fastest pace among
insect-scale robots. It can zip through tubes, climb small slopes and carry
small loads, such as a peanut.
Perhaps most impressively, the robot, which weighs less than one tenth of a
gram can withstand a weight of around 60 kg — about the weight of an average
human — which is approximately 1 million times the weight of the robot.
“People may have experienced that, if you step on the cockroach, you may
have to grind it up a little bit, otherwise the cockroach may still survive and
run away,” Lin said. “Somebody stepping on our robot is applying an
extraordinarily large weight, but [the robot] still works, it still functions.
So, in that particular sense, it’s very similar to a cockroach.”
The robot is currently “tethered” to a thin wire that carries an electric
voltage that drives the oscillations. The team is experimenting with adding a
battery so the robot can roam independently. They are also working to add gas
sensors and are improving the design of the robot so it can be steered around
obstacles.
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