MIT CSAIL’s swarm of robotic cubes can shapeshift at will

Collaborative robots have captured the public’s imagination for decades, and it’s no wonder — machines can achieve incredible feats by working together as a team. One need look no further for evidence than a new study from the MIT’s Computer Science and Artificial Intelligence Lab (CSAIL), which was supported in part by the National Science Foundation and Amazon’s robotics division. Building on a project that kicked off six years ago, researchers developed self-assembling cubes capable of climbing over and around one another, leaping through the air, and rolling across the ground.

It’s not the first time a team at MIT CSAIL has investigated modular robots tailored to specific tasks. A paper and accompanying blog post published in August detailed autonomous robotic boats, or roboats, designed to shapeshift at will across bodies of water by reassembling into different configurations.

“The unique thing about our approach is that it’s inexpensive, robust, and potentially easier to scale to a million modules,” CSAIL PhD candidate and lead author on the study John Romanishin said in a statement. “[The cubes] can move in a general way. Other robotic systems have much more complicated movement mechanisms that require many steps, but our system is more scalable and cost-effective.”

The 50-millimeter blocks, dubbed M-Blocks, communicate using barcode-like patterns (MFTags) on each of their faces and edges. The patterns are created by arrangements of permanent magnets that encode information passively, like relative orientation and identifying numbers.

The cubes contain flywheels that move at 20,000 revolutions per minute using angular momentum, which enables them to move initially in four cardinal directions (24 total different movement directions) when placed on any one of their six faces. A mass within them kicks off rotations and movements as it’s “thrown” against the inside, and the magnets allow any two of the cubes to attach together temporarily.

In the course of several experiments, the team investigated model-driven behaviors implemented on a group of a dozen blocks tasked with accomplishing simple goals. They evaluated the modules’ ability to identify and follow arrows embedded in a set of passive and temporarily disabled blocks, for example, and the blocks’ proclivity to forming single horizontal lines from complex 3D structures.

The results weren’t a slam dunk. The team reports high error rates due to manufacturing and design limitations, which they blame on the hardware’s “preliminary” nature. Still, they claim that 90% of the M-Blocks succeeded in getting into a line.

“M stands for motion, magnet, and magic,” said MIT professor and CSAIL director Daniela Rus, who wrote the paper alongside Romanishin and John Mamish of the University of Michigan. “Motion because the cubes can move by jumping. Magnet because the cubes can connect to other cubes using magnets, and once connected they can move together and connect to assemble structures. Magic because we don’t see any moving parts, and the cube appears to be driven by magic.”