Science in Mind

Intelligence of the swarm; robots build complex structures

Compared with human-like robots that are being built to comprehend emotion, perform complex tasks, and outsmart people on quiz shows, a trio of bug-like machines designed by Harvard University engineers with a handful of crude sensory abilities hardly seems to merit the word “intelligence.”

But this seemingly rag-tag team of robots is one example of a powerful alternate approach to tackling complex problems; instead of trying to build one really smart machines, build a bunch of average ones. Inspired by termites, which can accomplish astonishing feats of engineering despite having no mastermind foreman telling them what to do, the researchers decided to see if droves of simple robots, each one individually expendable, could be engineered to carry out a complex task.

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In a study published in the journal Science on Thursday, the team from the Wyss Institute for Biologically Inspired Engineering described what can best be called a kind of collective intelligence. A team of robots given a picture of a structure they’re supposed to build can do so not by following a preset plan, but by sensing what exists in the environment and following a few simple rules.

They do not need to communicate with one another about what they are each doing. They do not need a central computer to tell them what steps to follow and when. And they don’t need to know how the structure has changed since they laid down the last brick. They merely work together toward an end goal.

“Every robot is doing its own thing and doesn’t know anything about the rest. If they break or they’re lost, the rest of them can keep on working without changing anything about what they’re doing,” said Justin Werfel, a research scientist at the Wyss. “There’s no need for a central brain to stop and replan what the smaller workforce should do. If you want to add more robots, nothing has to be reprogrammed.”

The robots are building small structures out of foam blocks, not laying bricks or carrying sandbags, but the researchers think that the same concepts could be applied to more capable robots to one day build structures in dangerous environments. Perhaps they could prepare a facility on Mars for people, or build levies to prevent floodwaters from destroying property.

The way it works is fairly straightforward: a central program is given a picture of the structure and then creates a very basic set of traffic rules, said Kirstin Petersen, a graduate student at Harvard. Those rules basically tell the robots which way they can walk through the structure and what the end goal is. Then, the robots work from there, following the simplest requirements, such as that they can only use their “whegs”—wheel-like legs—to climb up one bricks’ length in height. They can only set down a brick at their own height.

Much work remains to be done; the robots have only so far built up nine-brick structures in the laboratory. But as they continue to work on the project, researchers are going back to nature for inspiration. They plan to study in closer detail how termites build massive and complex structures with no centralized intelligence.

The world of swarm robotics is challenging the popular idea that the future of robotics is simply about smart machines. In fact, asked what she might have done differently if she were to start the project over again, Petersen said she might make the robots even simpler.

“If I built up a new system, I might make the robots less capable,” Petersen said. “But make more of them.”

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