 |
| A team at the University of Southern California has built an 88-milligram "RoBeetle" that runs on methanol and uses an artificial muscle system to crawl, climb, and carry loads on its back for up to two hours Xiufeng YANG Xiufeng Yang, University of Southern California/AFP |
Washington (AFP) - Scientists have long envisioned building tiny robots capable of navigating environments that are inaccessible or too dangerous for humans -- but finding ways to keep them powered and moving has been impossible to achieve.
A team at the University of Southern California has
now made a breakthrough, building an 88-milligram (one three hundredth of an
ounce) "RoBeetle" that runs on methanol and uses an artificial muscle
system to crawl, climb and carry loads on its back for up to two hours.
It is just 15 millimeters (.6 inches) in length,
making it "one of the lightest and smallest autonomous robots ever
created," its inventor Xiufeng Yang told AFP.
"We wanted to create a robot that has a weight
and size comparable to real insects," added Yang, who was lead author of a
paper describing the work in Science Robotics on Wednesday.
The problem is that most robots need motors that are
themselves bulky and require electricity, which in turn makes batteries
necessary.
The smallest batteries available weigh 10-20 times
more than a tiger beetle, a 50 milligram insect the team used as their
reference point.
To overcome this, Yang and his colleagues engineered
an artificial muscle system based on liquid fuel -- in this case methanol,
which stores about 10 times more energy than a battery of the same mass.
The "muscles" are made from nickel-titanium
alloy wires -- also known as Nitinol -- which contracts in length when heated,
unlike most metals that expand.
The wire was coated in a platinum powder that acts as
a catalyst for the combustion of methanol vapor.
As the vapor from RoBeetle's fuel tank burns on the
platinum powder, the wire contracts, and an array of microvalves shut to stop
more combustion.
The wire then cools and expands, which once more opens
the valves, and the process repeats itself until all the fuel is spent.
The expanding and contracting artificial muscles are
connected to the RoBeetles' front legs through a transmission mechanism, which
allows it to crawl.
The team tested their robot on a variety of flat and
inclined surfaces made from materials that were both smooth, like glass, and
rough, like mattress pads.
RoBeetle could carry a load of up to 2.6 times its own
weight on its back and run for two hours on a full tank, said Yang.
By contrast, "the smallest battery-powered
crawling robot weighs one gram and operates about 12 minutes."
In the future, microbots may be used for a variety of
applications like infrastructure inspection or search-and-rescue missions after
natural disasters.
They might also assist in tasks like artificial
pollination or environmental monitoring.
Roboticists Ryan Truby and Shuguang Li, of MIT and
Harvard respectively, wrote in an accompanying commentary that RoBeetle was
"an exciting microrobotics milestone," but added there were also
opportunities for improvement.
For example, the robot is limited to continuous
forward motion, and taking electronics out of the equation reduces its capacity
to carry out sophisticated tasks.
No comments:
Post a Comment