October 5, 2013
MIT Team Has Devised A Surprisingly Simple Scheme For Self-Assembling Robots
[ Watch the Video: Small Cubes that Self-Assemble ]
Brett Smith for redOrbit.com - Your Universe Online
In the blockbuster action movie Terminator 2: Judgment Day, a liquid-metal robot from the future is able to hunt down humans by manipulating its body shape into whatever it might need for a particular situation.
While they may not be working with liquid metal, MIT researchers have devised a robotic system capable of arranging into a wide range of three-dimensional shapes. Known as M-Blocks, the system is comprised of a series of mechanical blocks that spin, flip and jump individually – allowing for them to configure as a group into a range of shapes.
Using an internal flywheel capable of reaching speeds of 20,000 revolutions per minute, the M-Blocks are able to move about without any external parts. To move a block, the flywheel is accelerated and then quickly stopped – imparting its angular momentum to the cube. A series of magnets on each edge and surface of the blocks are arranged to facilitate two cubes attaching or moving around to each other.
“It’s one of these things that the [modular-robotics] community has been trying to do for a long time,” said Daniela Rus, a professor of electrical engineering and M-Block developer at MIT. “We just needed a creative insight and somebody who was passionate enough to keep coming at it — despite being discouraged.”
According to Rus, researchers studying reconfigurable robots have been using something called the sliding-cube model. In the model, if two cubes are facing each other, one of them can glide up the side of the other and then, without changing orientation, glide across its top.
While the M-Blocks are guided by this model, they are a revolutionary step forward because they abandon the idea of being able to hold the system in place during any part of the motion process, a principle known as being statically stable.
“There’s a point in time when the cube is essentially flying through the air,” said Kyle Gilpin, a postdoctoral associate at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL). “And you are depending on the magnets to bring it into alignment when it lands. That’s something that’s totally unique to this system.”
To ensure that the cubes come into a desired alignment, engineers placed ‘rolling pin’ magnets on each of the twelve edges. When two cubes approach each other, the magnets naturally rotate to opposing poles and lock two cube faces together. These rolling magnets also facilitate one cube rolling over the edge of another.
The MIT team said they envision the cubes eventually being able to be customized to contain cameras, lights, battery packs, or other equipment.
“In the vast majority of other modular systems, an individual module cannot move on its own,” Gilpin said. “If you drop one of these along the way, or something goes wrong, it can rejoin the group, no problem.”
“What they did that was very interesting is they showed several modes of locomotion,” observed Hod Lipson, a robotics researcher at Cornell University. “Not just one cube flipping around, but multiple cubes working together, multiple cubes moving other cubes — a lot of other modes of motion that really open the door to many, many applications, much beyond what people usually consider when they talk about self-assembly.”