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Courtesy of New Scientist Magazine
By Mark Ward
A colony of robots could soon be patrolling farmers' fields, killing slugs and powering
themselves with the corpses of their victims.
Last week, Britain's Department of Trade and Industry gave away £19·5 million to 233
projects under the Realizing Our Potential Award (ROPA) Scheme. One scheme awarded two
years of funding will attempt to create a colony of at least four robots that will hunt
for slugs on arable land. Once a robot has captured a full load of slugs it will return to
base and dump them into a fermenter. Biogas produced by the rotting corpses will power a
generator that will recharge the robots' batteries.
"We are trying to find out if it is possible to build a robot system that needs no
human intervention to keep it going," says the project leader, Owen Holland of the
Intelligent Autonomous Systems Engineering Laboratory at the University of the West of
England in Bristol .
Holland says that one of the challenges of the project is to ensure the robots leave
enough time to return to base before they run out of power. They must also patrol the
whole of their territory, not just one patch, and not get in each other's way, he says.
The base station is needed because robots would soon become bogged down in soft
agricultural soil, says Holland. With a colony of four or more robots, some can be
foraging as others recharge.
Holland says slugs were chosen because they are a recognized agricultural pest that is
difficult and expensive to eradicate. British farmers spend £10 million each year on slug
pellets. And the metaldehyde and methiocarb ingredients in slug pellets build up in the
bodies of mammals and birds that prey on slugs, and can eventually kill them. When the
natural predators die, slugs can dine on crops with impunity.
Holland says there is little risk that the robots will run out of slugs to fuel their
foraging. Recent surveys carried out by one of the advisers to the project--the Long
Ashton Research Station in Bristol--found 200 slugs in every square meter of a field of
But the main reason that slugs were chosen was because they do not run away. "Since
slugs move slowly, they can be caught without active pursuit," says Holland. Although
slugs do have a response against predators, it consists merely of rocking gently from side
The robots have not been designed yet but they will probably hunt by taking snapshots of
their territory while on patrol. While patrolling they will take successive snapshots and
compare the images. If a slug-sized patch has moved, the robot will home in on the target
and capture it.
Holland says all the ROPA projects have an element of risk and the end result of the
project will not be a commercial product. "We are not trying to design a finished
system," says Holland, "we just want to see if it works." Work on the
project begins in October.
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