August 12, 2012
Researchers Develop Soft Autonomous Robot That Moves Like An Earthworm
|A team of researchers from MIT, Harvard University and Seoul National University has created a robotic earthworm called Meshworm. Moving like an earthworm, it crawls across the floor via peristaltic motion. Unlike an earthworm and despite its soft exterior, it is remarkably tough and can survive hammer blows and more.|
Now researchers at MIT, Harvard University and Seoul National University with DARPA funding have engineered a soft autonomous robot that moves via peristalsis, crawling across surfaces by contracting segments of its body, much like an earthworm. The robot, made almost entirely of soft materials, is remarkably resilient: Even when stepped upon or bludgeoned with a hammer, the robot is able to inch away, unscathed.
This motion is a contrast to the rectilinear motion and slithering motion that has been employed on snake robots.
Sangbae Kim, the Esther and Harold E. Edgerton Assistant Professor of Mechanical Engineering at MIT, says such a soft robot may be useful for navigating rough terrain or squeezing through tight spaces.
The robot is named “Meshworm” for the flexible, meshlike tube that makes up its body. Researchers created “artificial muscle” from wire made of nickel and titanium — a shape-memory alloy that stretches and contracts with heat. They wound the wire around the tube, creating segments along its length, much like the segments of an earthworm. They then applied a small current to the segments of wire, squeezing the mesh tube and propelling the robot forward. The team recently published details of the design in the journal IEEE/ASME Transactions on Mechatronics.
In addition to Kim, the paper’s authors are graduate student Sangok Seok and postdoc Cagdas Denizel Onal at MIT, associate professor Robert J. Wood at Harvard, assistant professor Kyu-Jin Cho PhD ’07 of Seoul National University, and Daniela Rus, professor of computer science and engineering and director of MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL).
In the past few decades, many roboticists have looked for ways to engineer soft robotic systems. Without bulky, breakable hardware, soft robots might be able to explore hard-to-reach spaces and traverse bumpy terrain. Their pliable exteriors also make them safe for human interaction.
A significant challenge in soft robotics has been in designing soft actuators, or motors, to power such robots. One solution has been to use compressed air, carefully pumped through a robot to move it. But Kim says air-powered, or pneumatic, robots require bulky pumps. “Integrating micro air compressors into a small autonomous robot is a challenge,” Kim says.
Instead, Kim and his colleagues looked to the earthworm for design guidance. They noted that the creepy crawler is made up of two main muscle groups: circular muscle fibers that wrap around the worm’s tubelike body, and longitudinal muscle fibers that run along its length. Both muscle groups work together to inch the worm along.
The team set out to design a similar soft, peristalsis-driven system. The researchers first made a long, tubular body by rolling up and heat-sealing a sheet of polymer mesh. The mesh, made from interlacing polymer fibers, allows the tube to stretch and contract, similar to a spring.
They then looked for ways to create artificial muscle, ultimately settling on a nickel-titanium alloy. “It’s a very bizarre material,” Kim says. “Depending on the [nickel-titanium] ratio, its behavior changes dramatically.”
The group also outfitted the robot with wires running along its length, similar to an earthworm’s longitudinal muscle fibers. When heated, an individual wire will contract, pulling the worm left or right.
As an ultimate test of soft robotics, the group subjected the robot to multiple blows with a hammer, even stepping on the robot to check its durability. Despite the violent impacts, the robot survived, crawling away intact.
“You can throw it, and it won’t collapse,” Kim says. “Most mechanical parts are rigid and fragile at small scale, but the parts in Meshworms are all fibrous and flexible. The muscles are soft, and the body is soft … we’re starting to show some body-morphing capability.”
Kellar Autumn, a professor of biology at Lewis and Clark College, studies the biomechanics of animal motion in designing soft robotics. Autumn says robots like the Meshworm may have many useful applications, such as next-generation endoscopes, implants and prosthetics.
“Even though the robot’s body is much simpler than a real worm — it has only a few segments — it appears to have quite impressive performance,” Autumn says. “I predict that in the next decade we will see shape-changing artificial muscles in many products, such as mobile phones, portable computers and automobiles.”
SOURCE MIT Press
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Tags: AI, artificial intelligence, CSAIL, Darpa, earthworm, mesh robot, meshworm, MIT, robotics, robots, Sangbae Kim, shape memory alloy, worm, worm robot
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