Carnegie Mellon University — The Robotics Institute funded the following project, whose results were then reported in the International Journal of Robotics Research by Mike Elgersma of Honeywell Labs. Mike wrote "Safe autonomous flight is essential for widespread acceptance of aircraft that must fly close to the ground. We have developed a method of collision avoidance that can be used in three dimensions in much the same way as autonomous ground vehicles that navigate over unexplored terrain. Safe navigation is accomplished by a combination of online environmental sensing, path planning and collision avoidance."

Mike reports results with an autonomous helicopter that operates at low elevations in uncharted environments, including some which are densely populated with obstacles such as buildings, trees and wires. More than 700 successful runs have been completed with an unmanned helicopter that traveled between specified waypoints separated by hundreds of meters. The helicopter safely avoided large objects as well as wires as thin as 6 mm as it went through its course at Fort Benning in Georgia. More than 700 missions were flown, and the UAV navigated at speeds up to 36 km/h at altitudes of between 5 to 11 meters.

According to Mike, "We believe this represents the first time an air vehicle has traveled this fast so close to obstacles. The collision avoidance method learns to avoid obstacles by observing the performance of a human operator." Certainly this capability would be of interest to military maneuvers with UAVs, especially in congested areas such as urban environments as well as disaster search and rescue ops. The Carnegie Mellon University test used a Yamaha RMax UAV helicopter, with a payload of 29 kg, which was modified to view obstacles encountered in its flights using a custom-built 3D scanner. The craft, measuring 3.5-feet in length, uses the scanner to sweep ahead of the flight path up to 150 meters away. An existing 3D map is used to plot a general flight plan that takes into account large obstacles, which may either be preloaded or built by the helicopter as new areas are entered. Then, as other unplotted obstacles appear, the craft's local planning system is activated and detours are plotted. This craft can actually fly between two obstacles with but 3 meters of clearance on each side.

The images are courtesy of Carnegie Mellon. The first photo shows the unmanned helicopter flying between two poles that are 10 meters apart. The second image is of the Yamaha RMax helicopter.