Researchers from MIT, Harvard and Seoul National University have collaborated on a new robot that moves like an earthworm. The slinking, inching robot is being partially funded by DARPA because of the advances the project is making in autonomous soft robotics -- or those using flexible, soft materials. This type of robot could be useful for traveling across rugged terrain and navigating hard-to-reach spaces and their soft exterior makes them safe for human interaction.
An earthworm moves by alternately contracting and stretching one set of muscles that run down the length of their bodies and one set that wraps around their bodies. The muscles work together to create the inching motion.
In order to build a robotic version of the earthworm, the researchers, led by MIT professor Sangbae Kim, created a soft body by heat-sealing a rolled up tube of polymer mesh. The springiness of the mesh lets it stretch and contract. The team then used a nickel-titanium alloy that reacts to heat to create the muscles -- two that run lengthwise down the tube to replicate the long muscles of the earthworm and a tightly-coiled wire that wrapped around the tube to replicate the circular muscles.
MIT news explains:
They then fitted a small battery and circuit board within the tube, generating a current to heat the wire at certain segments along the body: As a segment reaches a certain temperature, the wire contracts around the body, squeezing the tube and propelling the robot forward.. Kim and his colleagues developed algorithms to carefully control the wire’s heating and cooling, directing the worm to move in various patterns.
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.
Getting the robot to crawl like an earthworm was just the beginning. The team also wanted to make sure the soft robot was strong, so they beat it up. With a hammer. And then stomped on it. The good news is that it handled it beautifully, crawling away with no damage sustained. Says Kim, "“You can throw it, and it won’t collapse. 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.”
You can watch a video of the tests below.
The robotic earthworm technology could eventually be used in next-generation endoscopes, implants or prosthetics or, even more interestingly, as shape-changing muscles in our gadgets, smart phones, computers and cars.