New UAV can fly safely close to the ground
UAVs are useful, but they cannot fly close to the ground because they cannot avoid hazards such as buildings, trees, and power cables; Carnegie Mellon researchers develop a UAV capable of “seeing” — and avoiding — such obstacles
One way to fly safely over enemy territory is to fly low in order to avoid enemy’s radar. Flying low to the ground, however, is a pilot’s nightmare: buildings, trees, and power cables, and other hazards all threaten to put an early end to the flight. Now there is a solution which will delight search-and-rescue teams as well as first responders and law enforcement: U.S. engineers have developed the first large robotic aircraft able to fly at low levels and weave around such obstacles. New Scientist’s Kurt Kleiner writes that giving UAVs this ability could aid not only search-and-rescue efforts after disasters, but military operations in urban areas.
Most UAVs do not have the capacity to sense and avoid obstacles at all — a significant barrier to their being allowed to fly in civilian airspace. Now engineers at Carnegie Mellon University in Pittsburgh have modified a commercial civilian UAV helicopter made by Yamaha to be able to see obstacles it encounters. The helicopter’s “eye” is a custom-built 3D laser scanner which sweeps an oval path ahead of the 3.5-meter long craft. The scanner can detect objects as hard to see as power lines from 150 meters away.
The helicopter uses two navigation strategies. First, a long-range planning algorithm uses an existing 3D map to work out a general course that avoids large obstacles like buildings and trees. That map can be preloaded, or built up by the helicopter as it explores a new area. When the aircraft flies a route, its scanner looks out for other obstacles. As these appear, a local planning system takes over and plots a detour. The UAV can fly between two obstacles with only around 3 meters clearance on each side.
The same two-part navigation strategy has been used successfully on wheeled robots in the past, developing the laser scanner made it possible on aircraft too. The helicopter was put through its paces at a fake urban environment in Fort Benning, Georgia, including buildings and wires only 6 millimeters thick. Over 700 missions, the system successfully navigated at speeds up to 36 kilometers per hour and altitudes of between 5 to 11 meters.
Jean-Christophe Zufferey, an engineer at Swiss Federal Institute of Technology in Lausanne, Switzerland, says that the Carnegie Mellon aircraft is the only large UAV in existence capable of flying so low and planning its way around obstacles.
