>From The Economist print edition
IN THE film "Terminator 2" the villainous "liquid metal" P-1000
assassin-bot was able to change shape so that it could ooze through narrow
bars, or turn its extremities into blades. Mark Yim of Xerox's Palo Alto
Research Centre (PARC) has more limited and benign ambitions. As he
explained to the AAAS meeting, rather than building murderous psychotic
androids, he is trying to create a robot for use in search and rescue
operations, deep-sea mining and space exploration. But like the P-1000, Dr
Yim's machine can change its outward form.
The PARC Polybot is made of a dozen or so identical modules. When ordered
to do so by its operator, it changes shape on the move by rebuilding
itself out of these modules. According to the terrain, it can adopt one of
three different arrangements. When crossing a level surface it becomes a
looped tractor tread. For travelling down stairs or climbing over an
obstacle it configures itself into a caterpillar. On rough ground it
changes into a four-legged "spider".
To achieve this trick, the segments talk to each other using infra-red
transceivers. They can then locate one another, align themselves using
small onboard motors, and lock and unlock from each other at will. The
computing power needed to control all this is distributed among separate
processors-one for each segment-although there is a control centre in one
module, which is as close as the Polybot comes to having a brain.
Besides versatility, Dr Yim hopes the general idea of reconfigurable
modular robots will ultimately create cheap and durable devices. Their
robustness would come from creating a system in which the failure of one
or two modules would not matter. Savings in cost would arise from the
system's modularity-that is, from having to manufacture only one sort of
component in order to build a wide variety of different devices.
Having proved the principle with a dozen modules, Dr Yim and his
colleagues are working on a more ambitious version. This machine, which
should be ready later this year, will have 200 modules. Eventually, it
will also be able to control its own behaviour. Let us hope it does not
develop any personality disorders.
Useless hypotheses: consciousness, phlogiston, philosophy, vitalism, mind,
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