Termite-Inspired Robot Construction Crews Build Complex Structures Without A 'Foreman'
When most people picture termites, they probably imagine swarms of tiny insects destroying the foundations of a houses. But some termite species are known not for destroying structures, but for building very complex ones. Certain species in Africa and Australia build soil mounds hundreds of times larger than themselves, and all without blueprints or a hierarchal organization. Inspired by these termites' methods, Harvard University scientists have created a robot construction crew that can build 3D structures like pyramids and staircases without direction from a "foreman."
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"The key inspiration we took from termites is the idea that you can do something really complicated as a group, without a supervisor, and secondly that you can do it without everybody discussing explicitly what's going on, but just by modifying the environment," said principal investigator Radhika Nagpal of Harvard School of Engineering and Applied Sciences.
With humans, construction projects are typically carried out by trained workers in a hierarchy. But Justin Werfel of Harvard's Wyss Institute and lead author of a study on the termite-inspired robots, says that insects tend to build things differently. "Normally, at the beginning, you have a blueprint and a detailed plan of how to execute it, and the foreman goes out and directs his crew, supervising them as they do it," said Werfel. "In insect colonies, it's not as if the queen is giving them all individual instructions. Each termite doesn't know what the others are doing or what the current overall state of the mound is."
The Harvard researchers spent four years building TERMES, a system of leaderless robots that use foam bricks to build structures larger than themselves (much like termites). There is no direct communication among among the robots. Rather, a TERMES robot is able to whether a brick in the structure has already been laid down, and if so, it knows that it should put the next brick down on top of it. This mirrors the way termite species in Africa, Australia and South America build massive structures, some 40 feet tall, without anyone directing the operation. This indirect communication process practiced by termites (and TERMES) is known as stigmergy. The termites sense what work the other termites have done on the mound and act accordingly.
The robots work alongside one another but do not have individual roles, so if one of the robots breaks down, the other robots can continue. Sensors in the robots alert them to the presence of other robots and bricks in their way.
TERMES is a proof of concept, and the creators say that an eventual commercialized TERMES system could still involve some sort of central controller. Robotic systems that rely on such a controller have certain benefits; controllers can, for instance, improve group efficiency and fix problems that arise. But systems with a central control can also shut down if something happens to the central controller.
"It may be that in the end you want something in between the centralized and the decentralized system-but we've proven the extreme end of the scale: that it could be just like the termites," said Nagpal. "And from the termites' point of view, it's working out great."
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