Helicopter able to detect and avoid objects autonomously
Autonomous obstacle avoidance by an unmanned helicopter has been demonstrated by a team from the University of Berkeley, California. Researchers with the Berkeley Aerial Robotics (BEAR) programme believe they are the first to develop a system that enables an autonomous helicopter to detect obstacles and recompute its course in real time so as to reach its original destination.
With funding from the US Defense Advanced Research Projects Agency's (DARPA) Unmanned Combat Armed Rotorcraft (UCAR) programme, the BEAR group is conducting research into avoiding unknown obstacles using non-linear model predictive control (MPC). Flight tests of MPC collision-avoidance technology were conducted last month using a modified Yamaha RMAX unmanned helicopter.
In one demonstration, the 3.6m (12ft) -long helicopter was programmed with a flight path that passed through an array of tents set up in the two-by-three grid as a mock "urban canyon". In one scenario, the presence of the tents was included in the flight plan, but the helicopter was responsible for avoiding them. In a second test, the tent locations were not included in the flight plan, so the helicopter had to detect and avoid them. UC Berkeley says the helicopter stayed close to its calculated flight path in both cases.
The RMAX was modified with two industrial-grade onboard computers running a QHX real-time operating system, with inertial navigation and global positioning systems to stabilise the helicopter and wireless modems and Ethernet networks for data communications. Laser scanners were used for obstacle detection, including one capable of generating a three-dimensional image of the terrain ahead.
Another test involved two unmanned helicopters flying towards each other "in a game of aerial chicken", says UC Berkeley. The machines regularly reported their positions to a ground station, which sent back information alerting each to the other's presence. The helicopters then adjusted their courses autonomously to fly around each other. "To our knowledge, we are the first to successfully test-fly multiple autonomous helicopters interacting with each other," says BEAR researcher Hoam Chung.
Obstacle detection and avoidance in low-altitude flight is a key element of DARPA's efforts to enable a team of UCARs to collaborate autonomously with manned US Army helicopters. Northrop Grumman is using the RMAX as a surrogate for its UCAR design.
GRAHAM WARWICK / WASHINGTON DC
Source: Flight International
