Swarm intelligence inspired by animals

Research could enhance surveillance photos, assist the military
By Bryn Nelson
Columnist
updated 11:14 p.m. CT, Sun., April. 13, 2008

It's never too late to learn about the birds and the bees.

Particularly when they can help enhance surveillance photos, quickly sort through military reports and even enable individual robots to navigate within an army of fellow automatons.

The secret behind these new research efforts derives from the basic rules of what's known as swarm intelligence, a scientific framework inspired by the way in which birds flock together, social insects swarm and dust particles swirl in the air.

By understanding and correctly applying the rules that animals or particles use to identify and align themselves with their neighbors, Oak Ridge National Laboratory computational scientist Xiaohui Cui said swarm intelligence can yield very fast, though often approximate, solutions. Even so, for an application like identifying the best evacuation route out of a city during an emergency, "getting something quickly is perhaps more important than making sure it's the absolute best system possible," said Jesse St. Charles, a University of Tennessee at Chattanooga graduate student working with Cui.

The ability to quickly cluster similar entities using minimal resources also could be a boon for military analysts tasked with searching through thousands of field reports for ones relevant to a specific course of action. To that end, Cui and St. Charles are working with both the U.S. Navy and Air Force to help them better organize their documents.

Flocking rules

The bird-flocking research underlying the duo's current effort was initiated by other scientists in the mid-'80s, mainly as a way to produce more realistic video games. From that early work, three basic rules emerged.

"The separation rule basically keeps the birds from colliding with each other. So as they get closer, there should be a stronger repulsive force," said St. Charles, who introduced his project earlier this year during a presentation at the annual conference of the American Association for the Advancement of Science. The second, and complementary, rule is known as the cohesion rule. "It says, 'I don't want to get too far away from my neighbors,' " he said. For the third, or alignment rule, birds gauge where their neighbors are flying and then align themselves with the group's average heading.

A few years ago, Cui added a fourth rule, which states that birds should only flock with the same species. For their database-sorting algorithm to work, documents should likewise clump only with those that are similar enough to be considered, say, another mallard instead of a Canada goose.

To determine whether documents really are birds of a feather, a database is first stripped of non-meaningful words and word endings. Each raw document is then analyzed for the frequency of remaining terms, resulting in an ID that its neighboring documents can use to assess their relatedness.

"What we've done is set up a virtual two-dimensional space like a game board," St. Charles said. "We randomly position these documents at the beginning, and randomly assign them a direction to fly in. Each document will fly in whatever direction for a small distance. And they will ask, 'Who is nearby me?' They look at their neighbors and then apply the four rules to the documents by them."

After a few hundred steps around the board, similar documents find each other and become locked in the same flocking pattern. And because they don't have to apply the rules to every document in the database, St. Charles said, the system is much speedier than other aggregators.

On average, the duo deals with about 3,000 to 10,000 documents and normally ends up with around eight to 10 main clusters. The system also preserves indirect relationships that might be lost with other methods requiring a document that pertains to airlines, defense contracts and Senate policy to be stored under a single subject heading.

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Additional comments on "Enhancing photographs" and "Route finding for Robots."

"No individual fully grasps the entire problem, whether the task is to defend a hive or migrate in a coordinated fashion, he said. But by acting on its own senses within its immediate surroundings, each animal influences its neighbors' behavior. Magnified across a large flock or swarm, "you get a global behavior of the whole system that can appear intelligent.""

Sound like a political party organization? Or maybe a megachurch?

Perhaps if this actually can be applied to government/military applications, the government could approach the collective intelligence of a flock of starlings.(?)

John