[Paleopsych] NS: Organised chaos gets robots going
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Sat Apr 23 08:59:11 UTC 2005
Organised chaos gets robots going
* 09:45 01 November 2004
* Will Knight
A control system based on chaos has made a simulated, multi-legged
robot walk successfully. The researchers behind the feat say it may
have brought us closer to understanding how people and animals learn
Standard robots control their leg motion either through complex
computer programs or by using so-called genetic algorithms to evolve a
successful walking strategy. Both these options are time-consuming and
require a lot of computer power.
Roboticists Yasuo Kuniyoshi and Shinsuke Suzuki wondered whether
chaotic systems might also generate efficient walking behaviour.
Chaotic systems behave in a way that means that small effects are
amplified so rapidly that the systems behaviour becomes impossible to
predict more than a short time ahead. Such chaotic systems are behind
a number of phenomena, including the weather and the performance of
The Tokyo University pair reasoned that just as the chaotic maths that
determines the weather can produce clear patterns such as hurricanes
and weather fronts, similar systems might underlie the movement
patterns involved in locomotion. We, and animals, seem to be able to
work out how to move in different situations without going through
thousands of trial-and-error situations like todays robot-control
software does, says Kuniyoshi.
To test their idea, Kuniyoshi and Suzuki devised a computer simulation
of a 12-legged machine in which each leg was controlled by a chaotic
mathematical function. The functions were initially fed 12 parameters
chosen at random. From then on, sensory information from each limb was
fed back into the chaotic function that controlled it.
The team found that certain combinations of starting parameters made
the robots limbs rapidly adopt walking-on-the-spot behaviour, but the
machine did not get anywhere. However, when they placed a weight at
one end of the simulated robot (see graphic) they found that four of
the legs seized up, allowing the front and back legs to dominate
movement and let the robot scamper along.
The robot could also negotiate obstacles in its path. After scuttling
about for a few seconds, its mode of locomotion would change to allow
it to scramble over whatever was in the way. Although it was just a
simulation, the software mimicked the robots performance in fine
detail. Kuniyoshi is confident that the trick will work in a real
Remarkably, the robot performed these tricks without any conventional
programming. And its behaviour emerged far more quickly than it would
if it had used genetic algorithms. Kuniyoshi suggests that his chaotic
approach may have similarities to the way that biological systems
learn to move.
Many findings point to the presence of chaotic patterns in general in
the human brain, says Max Lungarella, who researches artificial
intelligence at the University of Tokyo. But Kuniyoshi and Suzukis
approach is still unconventional, he says. It diverges radically from
the traditional way of thinking about intelligence.
Roberto Fernández Galán, a biophysicist at Carnegie Mellon University
in Pittsburgh, Pennsylvania, also finds the approach intriguing, but
he is sceptical about the Japanese teams idea that chaos plays a role
in animal locomotion. It is surprising to achieve what they call
goal-directedness with a chaotic robot, he says.
* Walking robot carries a person
* 21 November 2003
* Nine eyes help robots to navigate
* 30 October 2003
* Robot spy can survive battlefield damage
* 20 August 2003
* University of Tokyo
* Max Lungarella, University of Tokyo
* Roberto Fernández Galán, Carnegie Mellon University
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