Building a single, large-scale machine -- an android, if you will -- requires significant investments of time, energy and money. Another approach involves deploying an army of smaller, simpler robots that then work together to accomplish more complex tasks.
This brings a different set of challenges. A robot working within a team must be able to position itself accurately in relation to teammates and must be able to communicate effectively -- with other machines and with human operators. To solve these problems, scientists have turned to the world of insects, which exhibit complex swarming behavior to find food and complete tasks that benefit the entire colony. For example, by studying ants, researchers know that individuals use pheromones to communicate with one another.
Robots can use this same "pheromone logic," although they rely on light, not chemicals, to communicate. It works like this: A group of tiny bots is dispersed in a confined area. At first, they explore the area randomly until an individual comes across a trace of light left by another bot. It knows to follow the trail and does so, leaving its own light trace as it goes. As the trail gets reinforced, more and more bots find it and join the wagon train. Some researchers have also found success using audible chirps. Sound can be used to make sure individual bots don't wander too far away or to attract teammates to an item of interest.