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Yosi Bar-Cohen brings biomimetics within arm's
By Erin M. Schadt
Imagine sitting down to an arm-wrestling match. You place
your elbow on the table and reach across to grab your
opponent's hand. You grasp a hand, but it's not human.
Instead, the arm is powered by artificial muscles.
This scene may not be too far off due to efforts by SPIE
Fellow Yoseph Bar-Cohen, a senior research scientist and group
leader at the Jet Propulsion Laboratory (JPL; Pasadena, CA)
responsible for Nondestructive Evaluation and Advanced
Actuators (NDEAA) Technologies.
EAP in action
Bar-Cohen first pitched the idea to develop artificial
muscles to NASA's TeleRobotic Inter- center Working Group in
1995. From this sprang a four-year project called LoMMAs (Low
Mass Muscle Actuators) involving a team of scientists from
NASA, the Langley Research Center (Hampton, VA), and the
University of New Mexico (Albuquerque, NM).
This project was supported by the NDEAA lab, which
Bar-Cohen formed in 1991. This lab not only focuses on
actuators and robotics, but also on NDE methods, transducers,
and sensors. In 1999, NASA spotlighted Bar-Cohen and his
team's creation of a four-fingered gripping device and a
dust-wiper EAP actuator for space applications.
Also that year, Bar-Cohen initiated the first SPIE
conference "Electroactive Polymer Actuators and Devices
(EAPAD)" as a part of the Smart Structures and Materials
Symposium, and has chaired the conference each year ever
since. "To make this field more exciting, I came up with a
challenge to the world science and engineering community to
develop a robotic arm that would arm wrestle a human opponent
and win," he says. "Furthermore, I initiated a session called
'EAP-in-Action' at the EAPAD conference where developed
materials and devices are presented, and my hope is to have
the arm-wrestling match as part of this session."
But his passion for EAP doesn't stop there. He edited the
book Electroactive Polymer (EAP) Actuators as Artificial
Muscles—Reality, Potential, and Challenges, published in
2001 by SPIE Press. In addition, he and co-editor Cynthia
Breazeal took the field of artificial muscles to the next
level—biomimetic robots—in their book Biologically Inspired
Intelligent Robots, out soon from SPIE Press.
more than muscle
Yoseph and Denny
Bar-Cohen with their Shih-Tzu, Bamba.
Bar-Cohen isn't just about muscle, though. During
childhood, he says, "I enjoyed reading books about chemistry
tricks, and, of course, liked to impress the neighborhood kids
with the expertise that I gained."
During high school, Bar-Cohen was drawn to physics, finding
that it provides the foundation to understanding nature and
chemistry. He went on to earn his undergraduate degree in
physics from the Hebrew University (Jerusalem, Israel). "Right
around the time that I finished my undergraduate studies, the
university opened a new master's program in applied science
and technology. It had what I sought—a materials science
department—and I was the first student to graduate from this
program," he says.
In 1971, while a co-op student at the Israel Aircraft
Industry, he discovered the interdisciplinary field of
nondestructive evaluation (NDE), and earned a PhD at the
Hebrew University with the thesis topic of ultrasonic
visualization of defects using the analogy to optics.
Shortly thereafter, Bar-Cohen moved to the United States
with his wife, Denny, and young fraternal twins, Limor and
Yaniv, to work at the NDE branch of the Air Force Materials
Laboratory, Wright Patterson Air Force Base (Dayton, OH).
During his first year there, he discovered the polarization
backscattering (PBS) phenomenon, and later discovered the
leaky lamb waves (LLW) in composite materials.
"Actually, I was looking through a Schlieren system to see
if I could detect leaky surface waves, which was a phenomenon
that was widely studied in metals in the early '80s,"
Bar-Cohen explains. "To my surprise, I was getting similar
patterns even though I was using a relatively low-precision
system, and the phenomenon appeared in many angles as opposed
to the case of the surface waves. Out of concern that this was
an artifact, I conducted many experiments over a period of
three months before mentioning it to anyone."
Thankfully, he did share his work on PBS and LLW; the
resulting studies by NDE engineers are used around the world
to detect defects in composite structures. Because of this
innovation in the field of NDE, Bar-Cohen was awarded SPIE's
NDE Lifetime Achievement Award in 2001. He is also a fellow of
the American Society for Nondestructive Testing.
Since forming the NDEAA in 1991, "most of my time is
dedicated to research and development related to harnessing
the capabilities of electroactive materials for planetary and
other applications," he says. Mechanisms resulting from work
at JPL include the ultrasonic/sonic driller/corer (which won
the 2000 R&D Magazine award as one of the 100 most
innovative instruments of that year), piezopumps, the haptic
interface MEMICA, multi-radiation ferrosource, medical
treatment tools, biomimetics, and robotics. These innovations
and initiatives earned him the 2001 NASA Honor Award: NASA
Exceptional Engineering Achievement Medal.
"I attribute my success to my imagination, creativity, and
hard work; but above all, it comes from good collaboration
with top experts worldwide," Bar-Cohen says. "My idea of
cooperative research with interdisciplinary experts was
adapted from the world of the ants who collectively are
capable of performing impressive tasks that are far beyond
what they are expected to be able to do as individuals."
"My daughter, Limor, lives in Los Angeles," Bar-Cohen says,
"and is a social-science researcher at UCLA's Center for
Healthier Children, Families, and Communities. My son, Yaniv,
lives with his wife Dorin in Boston, and he is a Fellow at the
Harvard children's hospital, specializing in pediatric
cardiology." Denny is just as busy. She went back to school,
earned an MS in psychology, and is nearing completion on a PhD
in organizational psychology at the California School of
Professional Psychology, part of Alliant University.
Bar-Cohen and Denny find time to ride their tandem bicycle
on weekends, with their Shih-Tzu dog, Bamba, along for the
ride in the front basket. Bar-Cohen says one of his favorite
hobbies is telling jokes; he has even drafted a manuscript for
a joke book. And perhaps, sometime soon, he will be able to
add robotic arm-wrestling to his list of hobbies.