autonomous blocks

Groups of simple, working together robots can unlock stealthy abilities for achieving complex tasks. Getting these robots to attain a true hive-like mind of coordination, however, has proved to be a problem.

In an effort to modify this, a team from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) came up with an amazingly simple scheme: self-assembling robotic cubes that can climb over and around one another, jump through the air, and move across the ground.

Six years after the project’s first repetition, the robots can now “interact” with one other using a barcode-like system on each surface of the block that lets the modules to recognize one other. The independent fleet of 16 blocks can now complete simple tasks or behaviors, such as forming a line, tracking light, or following arrows.

Within each modular, “M-Block” is a flywheel that rotates at 20,000 revolutions per minute, using angular momentum when the flywheel is braked. On each frame and every face are permanent magnets that allow any two cubes attach to each other.

While the cubes can’t be influenced quite as easily as, say, those from the video game “Minecraft,” the team visualizes strong applications in scrutiny, and ultimately disaster response. Visualize a burning building where a staircase has vanished. In the upcoming days, you can imagine merely throwing M-Blocks on the ground, and watching them construct out a temporary staircase for climbing up to the roof, or down to the basement to save victims.

“M stands for magnet, motion and magic,” says MIT Professor and CSAIL Director Daniela Rus. “’Motion,’ because the cubes can move by hopping. ‘Magnet,’ because the cubes can attach to other cubes using magnets, and once connected, they can move together and join to assemble structures. ‘Magic,’ because we don’t see any working parts, and the cube seems to be driven by magic.”

While the mechanism is quite complex on the inside, the exterior is just the contrary, which enables more strong connections. Apart from inspection and rescue, the researchers also imagine using the blocks for things like manufacturing, gaming, and health care.

“The unique thing about our method is that it’s cheap, strong, and potentially simpler to scale to a million modules,” says CSAIL PhD student John Romanishin, lead author on a new research paper about the system. “M-Blocks can move in a general way. Other robotic systems have much more complex movement mechanisms that necessitate many steps, but our system is more scalable.”

Romanishin wrote the paper together with Rus and undergraduate student John Mamish of the University of Michigan. They had shown the paper on M-blocks at IEEE’s International Conference on Intelligent Robots and Systems in November in Macau.

Earlier modular robot systems usually tackle movement using unit modules with miniature robotic arms known as external actuators. These systems need a lot of coordination for even the simplest movements, with multiple commands for one hop or jump.

On the communication side, other attempts have included the use of radio waves or infrared light, which can quickly get awkward: If you have lots of robots in a small area and they’re all trying to send one other signals, it opens up a messy channel of confusion and conflict.

When a system uses radio signals to interconnect, the signals can intervene with each other when there are numerous radios in a small volume.

Previously in 2013, the team built out its mechanism for M-Blocks. They made six-faced cubes that move about using force called “inertial forces.” This means that, rather than using moving arms that help join the constructions, the blocks have a mass inside of them which they “throw” against the surface of the module, which allows the block to rotate and move.

Each module can move in four basic directions when placed on any one of the six faces, which results in 24 diverse movement directions. Minus the little arms and appendages sticking out of the blocks, it’s a lot easier for them to avoid collisions and stay free of damage.

Knowing that the team had undertaken the physical hurdles, the crucial challenge still persisted: How to make these cubes interconnect and reliably recognize the configuration of neighboring modules?

Romanishin came up with algorithms made to assist the robots accomplish simple tasks, or “behaviors,” which led them to the solution of a barcode-like system where the robots can sense the identity and face of what other blocks they’re linked to.

In one testing, the team had the modules turn into a line from a random structure, and they watched if the modules could decide the specific way that they were connected to each other. If they weren’t, they’d have to choose a direction and roll that way until they reached on the end of the line.

Fundamentally, the blocks used the configuration of how they’re connected to each other in order to direct the motion that they choose to move — and 90 percent of the M-Blocks accomplished in getting into a line.

The group notes that building out the electronics was very challenging, especially when trying to fit complicated hardware inside such a small package. To make the M-Block groups a larger reality, the team wants just that — increasingly more robots to make bigger swarms with stronger abilities for various structures.

The project was partly supported by the National Science Foundation and Amazon Robotics.

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