A Hive-Minded Approach to Construction

I love it when a plan comes together. Not everyone is so fond of planning, however. A group of engineers at the University of Pennsylvania thinks it is high time we — or robots, anyway — started winging it. After considering how swarms of creatures like bees and ants build complex structures without having an overarching plan, they wondered if a swarm of robots could be programmed to do the same. By taking this approach, they believe that structures could be built faster by simpler robots, and also that the process would be robust to the failures of individual robots.

To make this possible, the team had to develop a new paradigm in robotic construction. Instead of programming each robot with detailed blueprints, they created a set of local rules, or simple instructions based on the robot’s immediate surroundings, that allowed structure to emerge organically from collective action.

As a starting point, the researchers modeled virtual swarms of tiny robots in a simulated environment. Much like ants, these virtual robots had no idea what they were building. They were not following instructions or coordinating with a central planner. Instead, each robot reacted to local environmental cues, such as whether building material was present or whether it had bumped into another robot’s work. Despite the simplicity of each robot's behavior, it was found that the swarm could collectively produce complex, honeycomb-like structures.

In traditional manufacturing, including 3D printing, each step is tightly controlled and must be executed perfectly in sequence. A single failure, such as a jammed nozzle, can halt the entire process. In contrast, the researchers’ swarm approach promises a more fault-tolerant method. Because no single robot oversees construction, the failure of one unit does not derail the entire effort.

To design these rule-based behaviors, the team experimented with a dozen different variables in simulation, such as turning angles and movement speeds. They discovered that a certain amount of randomness in robot behavior was not only tolerable, but beneficial. In fact, varying these parameters influenced the final structure’s geometry, with some configurations enhancing material toughness by improving resistance to cracking.

Some might argue that by carefully tuning these parameters, a centralized plan is effectively being encoded into them in a roundabout way. That may be true, but that does not change the fact that the way in which the plan is carried out is still highly fault tolerant. Accordingly, whether or not one buys into the idea that there is no plan involved, this approach to manufacturing may still hold value.

While the current research is entirely simulation-based, the team is moving toward a real-world implementation. They are exploring practical ways for robots to deposit material, such as using electrochemical processes to grow structures around themselves. Building functional miniature robots capable of such work is still a challenge, but the researchers are optimistic. With some additional work, manufacturing could be more resilient and scalable in the future.