Swarms of robots that use electromagnetic forces to cling together
and assume different shapes are being developed by US researchers. The grand goal is to create swarms of microscopic robots capable of morphing into virtually any form by clinging together.
Seth Goldstein, who leads the research project at Carnegie Mellon University, Pittsburgh, in the US, admits this is still a distant prospect.
However,
his team is using simulations to develop control strategies for
futuristic shape-shifting, or "claytronic", robots, which they are
testing on small groups of more primitive, pocket-sized machines.
These prototype robots use electromagnetic forces to manoeuvre themselves, communicate, and even share power.
No moving parts
One
set of claytronic prototypes were cylindrical, wheeled robots with a
ring of electromagnets around their edge, which they used to grab hold
of one another. By switching these electromagnets on and off, the
so-called "claytronic atoms" or "catoms" could securely attach and roll
around each other (see video, top right).
The
robot’s wheels were not powered, so they had to rely entirely on their
magnets to manoeuvre themselves around. "These were the first mobile
robots without any moving parts," says Goldstein. They also used their
electromagnets to share power, to communicate, and for simple sensing.
Since
using magnetic forces are less efficient at smaller scales, the team
has now begun experimenting with electric forces instead.
The latest prototypes are box-shaped robots dubbed "cubes" that have six plastic arms with star-shaped appendages at the end of each.
These
stars have several flat aluminium electrodes and dock together, face
on, using static electricity. Electrodes on different stars are given
opposing charges, which causes the stars to attract each other. Once
connected, no power is needed to hold the stars together.
Micro-scale robots
Tests
have shown that it is possible to send messages and power to other
cubes over the same links. "Our hope is to assemble around 100 cubes to
experiment with ideas," Goldstein says.
Rob Reid at the US Air Force Research Lab
is collaborating with the Carnegie Mellon team to develop even smaller
prototype robots. Reid and colleagues can fold flat silicon shapes into
3D forms as little as a few hundred microns diameter.
"We
will drive those using electric forces too, by patterning circuits and
devices into the silicon design," Goldstein says. He predicts that by
the summer of 2008 they will have prototypes capable of rolling
themselves around this way.
Modularity is a popular theme with robotics researchers around the world. Other designs include Swarm-bots, Superbot, and M-TRAN.
Complex connections
"The physical mechanism for docking different pieces is really tough to do," says Alan Winfield, who works on artificially intelligent swarms at the Bristol Robotics Laboratory
in the UK. "Most use mechanical latches with hooks." Although these
physical connections are complex, they do not need power, Winfield
points out, unlike magnetic connections.
Using
electromagnetic forces may make more sense at smaller sizes, he adds.
"My guess is that electrostatic connectors will come into their own on
the micro scale where less power is needed to have a large effect," he
says.
But
software, not hardware, may be the biggest challenge facing researchers
working on swarms of robots, he says: "Right now we just don’t know how
to design a system that produces complex overall behaviours from a
group of simple agents."
Ultimately,
Goldstein believes his claytronic robots may one day achieve this, and
much more: "I’ll be done when we produce something that can pass a Turing test for appearance," he says. "You won’t know if you’re shaking hands with me or a claytronics copy of me."