MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: John G. Watson
FOR IMMEDIATE RELEASE
February 18, 1999
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 International
Society for Optical Engineering's 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 at
(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.
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