'Smart Pebbles' Self-Sculpt to Create Simple Objects
Inside the new "smart pebble robots," which can stick to each other to reproduce objects buried in their midst.
CREDIT: M.Scott Brauer, courtesy of MIT News
Two MIT researchers are working on creating "smart sand," a system in which people can bury a small object, then, moments later, pull out a 3D duplicate of that object, created out of the particles. The particles are not quite the size of sand grain particles yet, though. They're created and tested their system in what they call "smart pebble robots," cubes that are 10 millimeters on each side that can self-assemble to create 2D objects that are one cube thick. They've also performed computer simulations that show the system will work with 3D objects thicker than one cube. The research pair, robotics professor Daniela Rus and doctoral student Kyle Gilpin, will present their latest work at the Institute of Electrical and Electronics Engineers' robotics conference in Minneapolis on May 16.
Each smart cube is its own mini-computer. Each has a microprocessor inside, so it can perform independent computations. Four of each cube's faces are equipped with special magnets the cube uses to communicate with, and stick to, others. With all the circuitry wound inside each cube, there wasn't room to place magnets on all six faces, Gilpin told MIT News.
The cubes get to work when someone nestles an object in their midst. Like any good puzzle-solver, they start with borders first. The cubes then communicate with each other until they determine which ones are touching the edges of the buried object. Then each of the "border pieces" sends a message to another pebble some distance away, reproducing a border in another part of the pile. Then the pebbles inside the newly created border know they're supposed to be part of the inside of the new object, so they link to each other, creating a duplicate of the buried object. All the other cubes fall away from the new object.
Rus and Gilpin still need to work on the electronics in the smart pebble robots to get them into tiny grains of sand, which would help them recreate objects with smoother surfaces than 10-millimeter cubes can make.
A search of the Institute of Electrical and Electronics Engineers' publications shows that Rus and Gilpin have been working on their smart pebbles since at least 2007. This year's presentation will show improved algorithms that let the cubes work even if they're imperfectly packed around the object they want to duplicate, if there are some missing cubes around the border of the object, or if some of the communication links between cubes fail, according to their abstract. This year's cubes are also two millimeters smaller on each side than their predecessors from 2011.
At the 2011 robotics conference, the smart pebbles' creators submitted a paper in which they imagined how they hope smart sand will eventually work. Someone with a bag of the sand could bury any object they choose, shake the bag, then pull out a duplicate or several duplicates, either of the same size or larger. When the person is done using the duplicate objects, he can drop it back into the bag, shake, and the object will fall apart into individual sand grains again, ready for reuse.
"Such a system would be useful for an astronaut on an interplanetary mission or a scientist isolated at the South Pole," Rus and Gilpin wrote. In more familiar lands and climes, surgeons and mechanics may appreciate being able to create unique tools, they said.