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A ROBOT in Edinburgh is finding its way around with the help of smart ears
that have “evolved” to help it echolocate like a bat. Researchers at the
University of Edinburgh who developed the RoBat say that cars equipped with
similar biologically inspired sound sensors could one day make roads safer.

Jose Carmena and his colleagues in the university’s department of infomatics
started out by fitting the RoBat with a central sound source, mimicking a mouth,
and two fixed receivers at a distance apart comparable to a bat’s ears. They
then improved its performance by evolving ears that focus the echoes as
efficiently as possible.

To do this, the researchers used a genetic algorithm that mimics natural
selection to get the best design. The algorithm operates on an artificial
chromosome—a data string representing the ear’s shape. First the
chromosome was mutated 100 times. The algorithm then tested each mutated version
to see how well it performed, and bred the “fittest” together to produce a new
offspring. After the process had been repeated 1000 times, the best chromosome
was used to build the RoBat’s ears.

The evolved ears led to a huge improvement in the robot’s performance. “We
can effectively double the resolution,” says John Hallam, who oversaw the
Edinburgh project.

The RoBat has also learned some other tricks from bats for making the best
use of the echoes. Bats move their ears to detect interference patterns in the
reflected sound waves, which they can interpret to help them avoid obstacles,
navigate and capture prey, says Carmena.

The Edinburgh team exploits a similar technique to help the RoBat navigate
more intelligently. “Ultrasonic sensors are widely used by robots,” says
Carmena. But these can only measure the time of flight: the smart ears give much
more information, such as elevation, as well as range. “To use one intelligent
sensor instead of 24 dumb sensors makes sense,” he says.

Similar technology could one day help cars to avoid collisions. Mercedes is
already using ultrasonic sensors to help drivers reverse, Carmena says. A number
of motorway “lane guard” systems are also being developed. These could be made
far more robust and reliable using a smart acoustic sensor like the RoBat’s ear,
says the Edinburgh team.

RoBat should also help biologists studying echolocation to understand what
type of information is available to the bat, says Carmena.