CAMBRIDGE, Mass.-They can go around obstacles, look for food and even play tag. They're programmed to behave like ants in a colony, but they're not insects-they're matchbook-sized robots.
The "Ants" are the creation of James McLurkin, a senior in electrical engineering and computer science at the Massachusetts Institute of Technology. Each robot is essentially identical to Cleo, a micro-robot he designed that was once considered as a basis for a remote-controlled colon surgery device.
He is building on the earlier work of robot communities begun by scientists including his faculty advisor Rodney Brooks, professor of electrical engineering and computer science and associate director of MIT's Artificial Intelligence Laboratory, and doctoral candidate Anita Flynn, who helped develop the first simple micro-robot in 1987. An earlier cooperative-robot project by PhD student Maja Mataric produced "toaster-bots" (named for their resemblance to the kitchen appliances) with names like Brioche, Zwieback and Wonder.
Cooperative robots could some day be used for tasks dangerous to humans but requiring the coordinated efforts of several workers. For example, power companies could use groups of disposable micro-robots to inspect pipes in nuclear power plants, saving the expense of shutting down the plant and safeguarding human inspectors. Government agencies have also expressed interest-the Department of Defense is funding research into algorithms that could be used to guide groups of robots in finding and picking up unexploded cluster bombs on battlefields, and the CIA is interested in micro-robots equipped with cameras and microphone for staking out buildings.
As of mid-April, Mr. McLurkin and his colleagues had built six new robot ants in two marathon sessions; he eventually hopes to have 21, which would be the largest robotic community in the world to date. Each has a pair of tiny treads powered by a battery and two motors taken from vibrating beepers. The robots are guided away from objects they hit and toward illumination sources by antennae and light sensors, and they also have mandibles powered by a third motor to pick up bits of "food"-quarter-inch balls of crumpled brass. Each micro-robot is named after one of Mr. McLurkin's female friends or relatives (Cleo is one of his grandmothers), since all worker ants are female, he explained.
Mr. McLurkin's goal is to have the robots behave cooperatively like an ant colony, seeking food and communicating with each other about where to find it. They do this with the aid of infrared transmitters and receivers (similar to those used by television remote controls) and software. If one robot finds food, it sends out the message "I found food;" others in the vicinity that receive it respond by heading toward the sender and signaling "I found a robot that found food," thus eventually spreading the word to the entire group. They also check once a second for the proximity of other robots to help avoid collisions.
So goes the theory. In practice, Mr. McLurkin has found that the robots tend to get confused if they receive signals from more than four other robots at once. He's also working out bugs on a program that make the Ants play tag. The robot that's "it" moves toward other robots, touches one with its antennae and then heads away from the new "it" robot (a human observer can keep track by noting each robot's array of red and green lights that indicate whether an Ant robot is "it" or not).
It's impossible to get robots to act exactly like ants because of the sophistication of ant behavior, and because "nature solves a lot of problems differently from the way people think they should be solved," Mr. McLurkin observed. However, his task is made easier by the fact that individuals (either real ants or robots) can fail and yet the group as a whole can still succeed. Programming the Ants has also become easier since the robots got 8K of memory, compared to just 2K a year ago, he added.
Although his co-workers in the micro-robotics group (including thesis supervisor Anita Flynn, who is receiving her PhD) are departing, Mr. McLurkin will stay on after graduation as a research scientist.
