| From: | chimerae@***.ie chimerae@***.ie |
|---|---|
| Subject: | Artificial muscles |
| Date: | Thu, 25 Feb 1999 22:55:44 +0000 |
days trying to get a simple text file forwarded to my home address :)
Read and start saving chummers:
ARTIFICIAL MUSCLES TO BE USED ON ROBOTIC SPACE EXPLORERS
Artificial muscles that should give space robots animal-like
flexibility and manipulation ability will get their first test on a
small NASA rover destined to explore an asteroid.
Under development by Dr. Yoseph Bar-Cohen of NASA's Jet
Propulsion Laboratory, Pasadena, CA, the artificial muscles are
based on a simple, lightweight strip of highly flexible plastic
that bends and functions similarly to human fingers when
electrical voltage is applied to it.
Bar-Cohen and a small team of scientists and engineers are
working to turn these strips into grippers and strings which can grab
and lift loads, among many other potential uses. These strips and
strings, known as artificial muscles or electroactive polymers (EAPs),
have the potential to greatly simplify robotic spacecraft tasks. The
technology could lead in the future to the development of insect-like
robots that emulate biological creatures.
Years from now, these devices could also conceivably replace
damaged human muscles, leading to partially "bionic men" and "bionic
women" of the future, according to Bar-Cohen and his fellow
researchers. "My hope is someday to see a handicapped person jogging
to the grocery store using this technology," said Bar-Cohen, leader of
JPL's Nondestructive Evaluation and Advanced Actuator Technologies
unit, although such "blue sky" medical applications, even if proven
feasible, may be decades away.
In the near-term, two EAP actuators are planned for use as
miniature wipers to clear dust off the viewing windows of optical and
infrared science instruments on the Mu Space Engineering Spacecraft
(MUSES-CN) nanorover. This mission, led by the Japanese space agency
ISAS, is designed to land the palm-sized rover on an asteroid
following its 2002 launch, and return a sample of the asteroid to
Earth.
"That's just the tip of the iceberg when it comes to space
applications," Bar-Cohen added. "Electroactive polymers are
changing the paradigm about the complexity of robots. In the
future, we see the potential to emulate the resilience and
fracture tolerance of biological muscles, enabling us to build
simple robots that dig and operate cooperatively like ants, soft- land
like cats or traverse long distances like a grasshopper."
Unlike human hands, which move by contracting and relaxing
muscles, typical robotic arms utilize gears, hydraulics and other
expensive, heavy, power-hungry parts. In future planetary exploration
missions, where robots will need to perform tasks like collecting and
manipulating samples of soil or ice, such mass and complexity becomes
a problem. To meet these challenges, Bar-Cohen and his team have
developed two types of artificial muscles that respond quickly to
small amounts of electricity by lengthening or bending.
The first is a flexible polymer ribbon constructed from
chains of carbon, fluorine and oxygen molecules. When an electric
charge flows through the ribbon, charged particles in the polymer get
pushed or pulled on the ribbon's two sides, depending on the polarity.
The net result: The ribbon bends. Using four such ribbons,
Bar-Cohen has fashioned a gripper that can pick up a rock.
The second consists of thin sheets wrapped into cigar-like
cylinders that stretch when one side of a sheet is given a
positive charge and the other a negative charge. These charges
cause the wrapped sheet to contract toward the center of the
cylinder, and this constriction forces the cylinder to expand
lengthwise. When the power supply is turned off, the cylinder
relaxes, enabling it to lift or drop loads.
Eight individual researchers or groups from around the world will
demonstrate their work on artificial muscles as part of the Society of
Photo-Optical Instrumentation Engineers' (SPIE) 6th Annual
International Symposium on Smart Structures and Materials in Newport
Beach, CA, in early March, with a media session planned for the
evening of March 2. Contact Pat Wright of the SPIE (360/676-3290,
x609) for further information on this event.
Further information about Bar-Cohen's research and related
activities is available at:
http://ndeaa.jpl.nasa.gov
A three-page fact sheet on the MUSES-CN rover is available
at:
http://www.jpl.nasa.gov/facts/muses.pdf
JPL is a division of the California Institute of Technology,
Pasadena, CA.
-end-
Martin Steffens
chimerae@***.ie
