Robot Cockroach Can Change Roach Group Behaviour

By Michael Bell

Researchers at the Free University of Brussels have previously demonstrated strongly groupish behaviour among populations of cockroaches; now one of the team has developed a tiny robot cockroach which can influence cockroach group behaviour.

The robot smells and acts like a cockroach, persuading the real insects, which rely on olfactory and tactile cues, to behave in unusual ways, for instance gathering in an illuminated shelter rather than in a dark one, which would be their normal preference.

'Insbot' is a wheeled robot about the size of a small matchbox, housing several computer processors hooked up to a camera and an array of infrared proximity sensors.

"If you don't put the pheromone molecules on them, the cockroaches get scared because they are afraid it is a predator," says roboticist Jean-Louis Deneubourg.

Deneubourg's team put 4 robots and 12 cockroaches in an enclosure with dark and lit-up areas. They programmed the robot to seek out real insects but also veer towards the lit area.

"It's important they prefer the light shelter, but not too much," Deneubourg says. "If they have too strong an attraction for the light they will go straight there and not interact with the real cockroaches."

The researchers plan to develop other robots that can socialise with animals and influence their behaviour in a similar way. They have already begun studying the group behaviour of sheep and chicken. "Chickens are a good example of a mixture of collective intelligence and leadership," Deneubourg says.

"It would be interesting to build our own intelligent societies of animals," says another member of the team.

Previous research at the University, led by Jean-Marc Am‚ and Jos‚ Halloy, senior research scientist, tested cockroach group behaviour by placing larvae of the insects in a dish that contained three shelters. The test was to see how the larvae would divide themselves among the shelters. Cockroaches gather in sheltered locations, or resting places, so the question was how they go about forming groups that maximize protection but minimize overcrowding. "Resting places are a nice experimental setup to test collective decision-making," Dr. Halloy said.

After much "consultation", through antenna probing, touching and more, the cockroaches divided themselves up perfectly. For example, if 50 of the animals were placed in a dish with three shelters, each with a capacity for 40, 25 of them grouped together in the first shelter, and 25 in the second, leaving the third shelter empty. If each shelter had capacity for 50 inmates, all the cockroaches moved into one shelter.

Halloy says that, in the absence of aural communications, cockroaches use chemical and tactile signals, plus visual cues, to communicate with each other. "When they encounter each other they recognise if they belong to the same colony thanks to their antennae that are 'nooses', that is, sophisticated olfactory organs that are very sensitive," he says.

During group decision-making, each insect appears to have equal standing and group consultations precede decisions that affect the entire group. Hallow says that as individuals, cockroaches benefit from living in groups through increased reproductive opportunities, sharing of resources like shelter or food, and the prevention of desiccation in dry environments."So what we show is that these behavioural models allow them to optimise group size."



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