Flocks of Flying Bluetooth Bots
By David Pescovitz, Thu Jun 09 11:00:00 EEST 2005

Flocks of flying Bluetooth robots may soon take to the skies for a distributed bird's eye view.


A typical flock of 2,000 starlings contains as much brain tissue as a single human being. Of course, you can't link together bird brains. Not real birds, anyway. But a small group of roboticists at the University of Essex are designing a system to wirelessly network a swarm of tiny, Bluetooth-enabled unmanned air vehicles (UAVs) into a cluster of flying computers acting as one processor more powerful than the sum of its bots.

Someday, flocks of shoebox-sized UAVs called UltraSwarms could act as a distributed eye in the sky, monitoring highway traffic, aiding in crowd control or even entertainment at massive sports arenas or, of course, embarking on military surveillance missions. Much of the data they gather -- video from onboard cameras, for example -- will be dealt with in the sky, delivering only "news you can use" to a central command. For any of these applications to fly though, the researchers must weave together two threads in computer science research: cluster computing and swarm intelligence. They're presenting a scientific paper (PDF) about the project at the 2005 IEEE Swarm Intelligence Conference this week in Pasadena, California.

"Flocking is a way to control a set of agents so they avoid collision," says PhD candidate Renzo de Nardi, a collaborator on the project with professor Owen Holland. "The flock takes care of itself and reacts to a changing environment without centralized control."

If a member of the flock is lost, the network, like the Internet at large, routes around it. The keys to this decentralization are novel algorithms that enable each vehicle to behave based on simple rules. For example, the first obvious rule is to avoid crashing into a neighbor. It's also important for a vehicle to match the velocity and direction of flockmates and, of course, to fly as close to neighboring vehicles as safety allows. The vehicles will keep tabs on each other either through video, wireless signal strength or a combination of the two. And by keeping tabs on each other, the hive mind emerges.

In the last decade, cluster computing -- gangs of computers combined into a unified system -- has become commonplace for high-performance applications like modeling biological phenomena. Traditionally, these clusters are networked together in a massive computer room over high-bandwidth ethernet lines. UltraSwarm aims to cut those wires with Bluetooth.

"Wireless technology is literally invading our world, but there have been very few experiments in wireless cluster computing," de Nardi says.

Who needs a supercomputer in the air though? The flock does, de Nardi says. For example, a single UAV on a military reconnaissance mission might have to pass over a location several times to gather video from a desired number of angles. That data would then have to be delivered to a remote command center for analysis by a speedy computer that would be far too bulky and power-hungry to fit on the UAV. On the other hand, a swarm of UAVs could gather the data in one pass and collectively process it across the cluster to suss out just the valuable bits.

"If you want to do sensible vision processing, you need a lot of power," de Nardi says. "An UltraSwarm could do the processing in the air instead of sending it to the ground and waiting for the results. The flock doesn't even need to be in range of a ground station."

After early experiments with model airplanes, the current prototype UltraSwarm aircraft is a tricked-out toy helicopter. The brains of the chopper are gumstix embedded platforms, computer modules powered by the same Intel XScale processors used in Linux smartphones. The tiny gumstix are equipped with Bluetooth, the wireless technology of choice for many roboticists.

"Bluetooth doesn't require a lot of power," de Nardi says. "Already, batteries account for almost half of the helicopter's weight. We have a big weight problem and the Bluetooth module is very light."

In many ways, the UltraSwarm bot is a quintessential node in the mobile Internet as it expands out, and up. Indeed, de Nardi believes that the chopper may be the smallest flying Web server in the world. The researchers programmed its embedded HTTP server to deliver an information page about the project and an image from the onboard camera.

"We did that to have a laugh with our colleagues," de Nardi says. "But within a few months, we hope to demonstrate our first flying flock."