The team of Harvard paves way for flood-defence robots

Temporary flood defences could one day be laid by an autonomous construction crew of termite-inspired robots, according to researchers in the US.

Engineers from Harvard University have demonstrated that their TERMES robots can build structures including towers, castles, and pyramids out of foam bricks without the need for a central control or supervising system that monitors and directs the robots.

The researchers say this could pave the way for larger robots that can autonomously build things in remote or dangerous situations such as sandbag defences in advance of a flood or structures on another planet, where a central control unit acts as a single point of weakness that could bring the whole system down.

`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 Prof Radhika Nagpal in a statement.

As well carrying and strategically placing bricks, the robots can build themselves staircases to reach the next construction points and add bricks that advance construction without blocking important paths. 

Their collaboration relies on a concept called “stigmergy”, the implicit communication that occurs as they observe each others’ changes to the environment and act accordingly. This means a structure can be built with any number of robots and the team can adapt if any individuals break down.

This contrasts with most human construction projects that are performed by trained workers in a hierarchical organization, said Justin Werfel, lead author on a paper on the research published in the journal Science.

‘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 a statement.

‘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 robots can perform all the necessary tasks—carrying blocks, climbing the structure, attaching the blocks, and so on—with only four simple types of sensors and three actuators.

‘We co-designed robots and bricks in an effort to make the system as minimalist and reliable as possible,’ said Kirstin Petersen, who spearheaded the design and construction of the robots.

‘Not only does this help to make the system more robust; it also greatly simplifies the amount of computing required of the onboard processor. The idea is not just to reduce the number of small-scale errors, but more so to detect and correct them before they propagate into errors that can be fatal to the entire system.’