|Self-assembling robots have been around for ages, from modules that
build themselves into a mechanical snake that can wriggle across the
floor, to robotic pieces that automatically stack to build a two-legged
walker. Most of those efforts involved designing modules that would add
themselves together, like very smart Legos, using internal electronics
and mechanics to self-assemble.
Now researchers at MIT have taken new tack. Instead of adding pieces,
they first pile the bits together, then shed the parts they don't need
to leave the desired shape. Their 'smart sand' is made up of individual
grains that are really one centimetre square cubes with microprocessors
inside and switchable magnets on four of their six faces which can talk
to each other electronically and sense their neighbours.
The team demonstrated how they work in two dimensions by placing a 2-D
'footstool' inside a grouping of blocks. The magnets are turned on, and
the modules check what is next to them on all four sides of the plane.
Then an algorithm calculates how to create the same pattern in an
adjacent region of block, and switches off magnets on the faces of the
module corresponding to those next to the footstool. This forms a copy
of the original object. Computer models show the same approach can work
in three dimensions.