'Insbots' shed light on insect decision-making behaviour

An EU-funded study has put theories of collective behaviour among insects into practice using a group of cockroaches as a model. As part of the LEURRE project, scientists introduced small,
autonomous robots into the group of insects and analysed their interaction.

According to a report in Science magazine, the experiment showed that self-organisation patterns of cockroaches and thus their decision-making could be influenced and controlled by the robots,
as soon as the insect-like micro-robots (insbots) had been socially integrated. This, the researchers achieved by wrapping the insbots in paper sprinkled with a blend of chemical compounds – a
kind of pheromone – which the insects use to identify each other. There was no physical resemblance between the ‘roach-bots’ and their natural counterparts.

In order to determine whether insects and insbots would in fact interact with each other, the researchers had set up an ‘arena’ with two ‘shelters’ for the group to choose between. ‘In the
first set of experiments, the shelters are perfectly equivalent,’ explained theoretical biologist Dr Jose Halloy of the Free University of Brussels in an interview with Science magazine. ‘If
they would chose randomly, we would end up with 50% of individuals on one side and 50% on the other side. But in this case we observed that we get 90% of individuals below the same shelter,
which means they have selected that shelter as a group.’

In the second set of experiments, Dr Halloy and his research group gave the mixed group of insects and robots a choice between a dark shelter and a lighter one. ‘Cockroaches naturally prefer to
go to dark places,’ said Dr Halloy. In modulating the behaviour of the robots and making them prefer lighter shelters, the researchers tried to influence the collective decision-making of the
system and succeeded in some instances, while in others the robots followed the cockroaches into the darker shelter.

‘The robots were driven somehow to the dark shelter by the system because of social interaction,’ Dr Halloy pointed out. ‘And it’s the same for the cockroaches: Although they prefer to be in
the dark place because they take into account the presence of others, including that of robots, they end up in the light place because of social interactions and not because they are driven by
individual preference only.’ However, the statistics showed that about 60% of the time the insbots tipped the balance in favour of the lighter shelter.

The scientists draw the conclusion that the behaviour of group-living animals can be studied and controlled using intelligent, autonomous devices. ‘Engineers are very interested in building
autonomous systems, groups of robots that are able to solve problems,’ said Dr Halloy. ‘The next step will be to build groups of artificial systems and animals that will be able to cooperate to
solve problems. So, the machine is listening to and perceiving what the animals are doing and the animals are perceiving and understanding what the machines are telling them.’

Practically, robots such as those used in the LEURRE experiment could aid pest control by luring insects into traps, or bigger versions could one day even help to herd livestock, suggested Dr
Daniela Rus of the Massachusetts Institute of Technology (MIT) in the US. In addition, the LEURRE study could provide new insights into the exploitation of the concept of self-organisation for
coordinating autonomous multi-robot systems such as swarm-robotic systems, which employ self-organisation as their main coordination mechanism.

The ?2 million LEURRE project received ?1.5 million in funding from the EU under the Fifth Framework Programme (FP5).

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