Crossbow's Motes were featured last month in an article on IEEE Spectrum. The application featured showcases how the Motes can be used when deploying mobile distributed communications networks.
The meter-long helicopters lined up under the fluorescent lab lights at the Berlin Technical University might look like overgrown toys, but they’ve got a little more under the hood. These are flying robots. They take off, land, and scout terrain autonomously and are being wired to deploy ad hoc communications sensor networks. And unlike any other robocopters, they can work together.
Researchers expect they’ll be used to distribute sensors that would help coordinate firefighting efforts or search flood zones, to track or find people and vehicles, or to shoot movies and cover sports events. Hoisting communications gear, they could one day help channel radio, Wi-Fi, or mobile phone traffic where infrastructure has been wiped out by an earthquake or other natural disaster.
Several groups around the world are working on miniaturized robot helicopters with advanced intelligence, notably in California, South Carolina, the Netherlands, South Korea, and the UK. But the Berlin team believes it is the first to write software and build systems that get multiple robot copters to collaborate. The project brings together a half-dozen institutions and companies from across Europe.
The copters’ control systems allow small craft to work together in lifting loads and scouting environments. Coordinated, the copters can lift weights that would normally require larger, exponentially more expensive machines. Estonian robotics engineer Konstantin Kondak, a professor at TU Berlin and one of the project’s leaders, says that having three or four copters in the air, each sharing the load while tethered by a rope to a single object, creates too many contrary forces for a set of human pilots to handle: “If you try to do this flying manually, it is not a stable system. You have to correct at all times; it’s too much.” But autonomous robots, making instant and coordinated adjustments, can do the job, he says.
Each robot must account for the location of the other helicopters, the forces coming from them, and the load on the rope, to jointly lift something. The helicopters’ coordination comes from a system that integrates four software modules for stabilizing the copter: one for navigation, one for exploration, one for obstacle avoidance, and one for processing orientation, horizon, and position.
The robocopters are good for much more than just lugging things around. Project manager Aníbal Ollero, a professor of engineering and automated systems at the University of Seville, in Spain, says that a flexible, easy-to-transport team of choppers makes for more efficient scouting because they automatically divide an area among themselves.
They’re also faster at another important task: deploying distributed communications networks by dropping off sets of tiny sensor nodes. These nodes combine a data processor, a radio, a battery, and—depending on what needs measuring—temperature, light, radiation, location, or chemical sensors. For the autocopter project, off-the-shelf nodes from wireless-sensor firms Crossbow Technology and Ambient Systems were optimized and linked by data-routing experts at universities in Stuttgart, Germany, and Twente, Netherlands. Just a few centimeters across and 7 millimeters thick, the individual nodes transmit over a range of just 25 meters, but as a network they pass radio messages to one another to get to a central unit (or hovering robocopter). Hundreds of thousands of these nodes could be distributed by robot to survey a forest fire or flood zone for rescue efforts, according to the researchers.
Final trials for the project get under way, far from the Berlin winter—this spring in southern Spain, Ollero says. If all goes well, helicopters will deploy a sensor network, track mobile objects and people, follow movement inside and outside of buildings, and capture it all with high-end airborne cameras.
For more information on Crossbow's Mote platforms, visit www.xbow.com.