MIT Deploys Swarm of Self-Assembling Robot Cubes

M-Blocks use internal flywheels to fling themselves around, and swarms of them could turn into anything

3 min read
MIT Deploys Swarm of Self-Assembling Robot Cubes

We started to get just a little bit nervous last spring, when Daniela Rus and Kyle Gilpin from MIT introduced something called "smart sand." Smart sand was a pile of tiny little robotic cubes endowed with the capability of autonomously replicating any 2D shape that you poured them over. The only reason we're not all robots right now (we're pretty sure we're not, anyway) is that smart sand couldn't move by itself: you had to shake it around a bunch to get it to do anything. For some reason, MIT has decided to remove that safety feature by developing a version of smart sand THAT CAN MOVE ALL BY ITSELF.

MIT research scientist John Romanishin has been working on (or at least thinking about) M-Blocks for the past several years, but from the sound of things, everyone thought he was nuts until he managed to actually go make it work. The way it works looks like magic, but it's just physics: by spinning an internal flywheel at up to 20,000 rpm and then suddenly applying a brake, the conservation of angular momentum causes the entire cube to flip, and in some cases, even jump an appreciable distance. There's only one axis of movement at the moment, but there's always the potential to add two more flywheels to enable movement in any direction.

The cubes stick to each other with an arrangement of magnets that encourage them to pivot around edges while sticking to faces. It's clever, but the issue with using permanent magnets is that it makes it difficult to stick one cube to another specific cube if there are cubes in the way: the only way to do it becomes with multiple powered movements, which wastes time and energy. It would be preferable to be able to toggle the magnets on each cube on and off, making it much easier to stick cube X to cube Y without having to worry about accidentally running into (and sticking to) cube N.

With this in mind, it's interesting to note that the Smart Sand used electropermanent magnets (magnets that you can turn on and off) to selectively get cubes to stick to one another. You can read a lot more about electropermanent magnets here, and that could be where M-Blocks are heading next. With selective attachment capabilities and three axes of control, we can imagine that a swarm of M-Blocks could start doing some wild things.

While we're on the subject of cubes, we certainly have to mention that the reaction wheel inside a cube idea was also tried out a few years ago at ETH Zurich, in Raffaello D'Andrea's lab. Cubli is still being actively worked on, and while they've gotten it to balance on a corner, they're still developing the jumping capability, although as of last year it was working in one dimension:

Last we heard, trying to do this with a full cube tended to lead to violent-self destruction due to the amount of energy involved. Cubli is much larger (and more massive) than an M-Block, making it exponentially harder to self-propel, but when they do eventually make it work, it'll be quite impressive.

Meanwhile, back at MIT, they're hard at work "building an army of 100 cubes." An "army." And they're not stopping with just one centuria, either:

The researchers believe that a more refined version of their system could prove useful even at something like its current scale. Armies of mobile cubes could temporarily repair bridges or buildings during emergencies, or raise and reconfigure scaffolding for building projects. They could assemble into different types of furniture or heavy equipment as needed. And they could swarm into environments hostile or inaccessible to humans, diagnose problems, and reorganize themselves to provide solutions.

"We want hundreds of cubes, scattered randomly across the floor, to be able to identify each other, coalesce, and autonomously transform into a chair, or a ladder, or a desk, on demand," Romanishin says.

Romanishin doesn't go on after this, but if he did, I'm reasonably sure that he's say something like:

"We also want them to be able to transform into creepy little self-replicating bug things, and we don't see how that could possibly go wrong."

The researchers will be presenting at the IEEE International Conference on Intelligent Robots and Systems in Japan (gasp) next month, where hopefully we'll get to see just how cool M-Blocks are in person.

[ MIT ]

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