Gumby-like flexible robot crawls in tight spaces

Harvard scientists have built a new type of flexible robot that is limber enough to wiggle and worm through tight spaces.

It's the latest prototype in the growing field of soft-bodied robots. Researchers are increasingly drawing inspiration from nature to create machines that are more bendable and versatile than those made of metal.

The Harvard team, led by chemist George M. Whitesides, borrowed from squids, starfish and other animals without hard skeletons to fashion a small, four-legged rubber robot that calls to mind the clay animation character Gumby.

In recent years, scientists have been tinkering with squishy _ sometimes odd-looking _ robots designed to squeeze through hard-to-reach cracks after a disaster like an earthquake or navigate rough terrain in the battlefield.

"The unique ability for soft robots to deform allows them to go places that traditional rigid-body robots cannot," Matthew Walter, a roboticist at the Massachusetts Institute of Technology, said in an email.

A team from Tufts University earlier this year showed off a 4-inch (10-centimeter) caterpillar-shaped robot made of silicone rubber that can curl into a ball and propel itself forward.

The Harvard project, funded by the Pentagon's research arm, was described online Monday in the journal Proceedings of the National Academy of Sciences.

The new robot, which took two months to construct, is 5 inches (12.7 centimeters) long. Its four legs can be separately controlled by pumping air into the limbs, either manually or via computer. This gives the robot a range of motions including crawling and slithering.

The researchers tested the robot's flexibility by having it squirm underneath a pane of glass just three-quarters of an inch from the surface.

Scientists maneuvered the robot through the tiny gap 15 times using a combination of movements. In most cases, it took less than a minute to get from side to side.

Researchers eventually want to improve the robot's speed, but were pleased that it did not break from constant inflation and deflation.

"It was tough enough to survive," said Harvard postdoctoral fellow Robert Shepherd, adding that the robot can traverse on a variety of surfaces including felt cloth, gravel, mud and even Jell-O.

There were drawbacks. The robot is tethered to an external power source and scientists need to find a way to integrate the source before it can be deployed in the real world.

"There are many challenges to actively moving soft robots and no easy solutions," Tufts neurobiologist Barry Trimmer, who worked on the caterpillar robot, said in an email.

Robotics researcher Carmel Majidi, who heads the Soft Machines Lab at Carnegie Mellon University, said the latest robot is innovative even as it builds on previous work.

"It's a simple concept, but they're getting lifelike biological motions," he said.

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Robot spider crawls out of 3-D printer

A rescue robot must have the mobility and balance to go where humans cannot, such as under the rubble of an earthquake-stricken city or inside the site of a nuclear reactor disaster. One of the best contenders has emerged in the shape of a jumping spider that bears an eerie resemblance to Mother Nature's own creepy crawlies.

The robot moves around as a real spider would by keeping four legs on the ground at all times while the other four prepare for the next step. Such mobility comes from combining rigid parts with an elastic body — a design that also allowed German researchers to create the robot spiders inexpensively by using 3-D printing.

"Our robot is so cheap to produce that it can be discarded after being used just once — like a disposable rubber glove," said Ralf Becker, a scientist at the Fraunhofer Institute for Manufacturing Engineering and Automation, in Stuttgart.

The spider robot's crawling and jumping abilities come from elastic drive bellows that act as joints. Instead of using muscles, the robot harnesses built-up body pressure to pump fluid into its legs to extend them. Bending the front pairs of legs pulls the robot spider along, and stretching its rear legs pushes it forward.

The current models have a control unit, valves and compressor pump in their body. In a disaster scenario, they could also carry video cameras, measuring devices and sensors to transmit information back to their human overseers.

The German team used 3-D printing to build up their robotic marvels layer by layer. During the process, a laser beam guided by a computer melts thin layers of polyamide powder to create the robot parts from the bottom up.

Such economic manufacturing allows the robotics researchers to almost effortlessly make modifications for new models. "We can ... produce one or even several legs in a single operation; this minimizes assembly effort, saves materials and reduces the time it takes to build a robot," Becker said. "With the modular approach, individual parts can be quickly swapped as well."

A prototype of the robot is scheduled to appear in Frankfurt at the EuroMold 2011 trade fair  (in Hall 11, Stand C66) from Nov. 29 through Dec. 2.