Wednesday, March 09, 2005

artifical muscles

AN DIEGO -- Six years ago, Jet Propulsion Laboratory researcher Yoseph Bar-Cohen challenged scientists to create an artificial arm that could beat a human in an arm-wrestling match. The catch: The arm must be made of a pliable plastic material controlled by electrical impulses. In other words, no motors allowed.

Monday, in front of a battalion of TV cameras and an audience of hundreds, three groups of scientists took on Bar-Cohen's challenge -- and failed. One of the robot arms seemed to flop helplessly, while the other two quickly fell to a 17-year-old high-school student.

Even if they had worked, the devices wouldn't have been ready for arm-wrestling competitions on ESPN: One relied on a potentially dangerous hydrochloric acid reaction, while another was powered by a strong electric current.

Nonetheless, Bar-Cohen still looked ecstatic after most of the media had left the International Society for Optical Engineering's Smart Structures/NDE conference. He hadn't expected anyone to take up his arm-wrestling dare for 20 years, and now one of the artificial arms managed to hold off the teenager for nearly a half-minute. "This is a major step," he said. "But it's a tough challenge."

It could mean the transformation of robots from large, clunky, motor-driven devices -- think of the robot arm that helped put together your car -- into sleek, sturdy, self-contained machines. You know, like humans.

"There could be some point where you can have a robot dog, not walking like a machine, but walking like a dog," said Bar-Cohen, a tireless advocate for the technology. "Or maybe a cheetah robot running on Mars instead of slowly rolling, climbing a mountain like we climb a mountain."

Humans and animals, after all, don't come with drive shafts and gears and wheels. Bar-Cohen and others expect that the artificial muscles will revolutionize prosthetics, allowing disabled people to more easily move their limbs.

For now, though, Ben-Cohen's dream muscles -- all made from plastics known as electroactive polymers -- are fairly primitive. The challenge is making the plastics bend and move with only a nudge from an electronic impulse, just like human muscles. Giving them the powerful strength of a live person is even harder.

Among other things, scientists have used the polymer technology to create a robotic fish and several traditional machines, but humanlike parts are still on the drawing board.

In the highly publicized arm-wrestling matches held Monday, each of the entrants tried to produce a "very simple arm that bends against the human hand," Ben-Cohen said. "There's no fancy capabilities to it, but with time we will increase the requirements."

The best-performing arm, created by a New Mexico company called Environmental Robots, was white and tapered toward the top, a bit like a bowling pin. Panna Felsen, a San Diego-area high-school student, took 24 seconds to push down the arm, which was controlled through power leads connected to two artificial muscles.

Felsen needed even less time to vanquish the second "arm" -- actually a small, polelike device with a round ball on the end designed by a Swiss laboratory. The arm was part of a 44-pound contraption powered by heavy voltage; Felsen had to wear a protective glove.

The final team, engineering students from Virginia Tech, used fishing lines to connect a fiberglass arm to several tubes holding gel fibers. The fibers were supposed to react with hydrochloric acid, pulling the fibers and moving the arm. It didn't work, apparently because the reaction took place too slowly.

Steven Deso, a senior, acknowledged that the arm had never beaten anyone before: "We had very little time for testing. We were focusing on safety." (Felsen wore safety goggles during the brief match.) But the students were still happy to have completed their project in just six months. "We met our goal," Deso said.

In many ways, of course, the arm-wrestling matches weren't fair fights.

The artificial arms hardly have the flexibility of the real thing, and a professional arm-wrestler pointed out that there's more to the sport than simple arm and shoulder power. "Arm-wrestling is your whole body," involving muscles from the

legs to the back, along with the pectorals and others, said Allen Fisher, who has won 21 titles.

Fisher said he was impressed by the robot arms, however, and predicted that once perfected, "they'll help a lot of people."

Artificial muscles may prove a boon for filmmakers. Richard Landon, who helped create the special effects for AI and the Jurassic Park movies, said technological advances could revolutionize his industry, allowing fake human characters -- or, say, velociraptors -- to free themselves from motors and look more natural.

For now though, Landon said, "it looks like we're not quite there yet."

End of story

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