Imagine telling robots to go build a five-bedroom house for you without telling them how to go about it. Now, scientists have created small robots that can do just that — build without a centralized plan — and termites were their inspiration. Unlike humans, who require both plans and planning to build something complicated, termites can build mounds hundreds of times their size without a coordinated strategy or detailed communication. Instead, they take simple cues from each other and their environment to know where to lay the next clump. This use of local information is called stigmergy.
Justin Werfel and colleagues leveraged stigmergy to design algorithms that reflect termite behavior, and then implemented these algorithms in a set of construction robots. Their bots need only the ability to sense a brick or bot nearby to make their next move. Equipped with sensors, they move along a grid, lifting and depositing bricks. If they sense a brick in their path, they carry their cargo to the next open space. Though each one “knows” only simple rules — like when to put a brick down or climb one step higher — together they exhibit intelligent behavior, completing user-defined structures. Critically, the particular unique user-defined structure determines the number of rules they know to follow.
So instead of the blueprint guiding their way, it’s the number of rules that’s important. Robot teams with this sort of independent, decentralized control are scalable; many robots can be added to a project, and they all still work together well. They may also be well-suited for environments that are dangerous, where if one gets swept away, the others, despite the loss (or not knowing about the loss), can keep working by following the cues of those robots that remain. A Perspective by Judith Korb provides additional insights.