Pushing the Envelope-Fast and Safe Landing by Autonomous Rotorcraft at Unprepared Sites

The process of selecting and landing at unprepared sites by rotorcraft is a complex problem that requires a combination of machine perception, route planning and online collision avoidance. The site itself must be determined to be flat and level and approaches must be conducted in a manner that keeps the vehicle safe from objects such as wires, trees and buildings that might not appear in digital maps. In addition, it is necessary to fly as low and fast as possible during approach to minimize threat and to continuously plan wave-off trajectories in case the landing site is determined to be unsuitable just before landing. However, all such factors must be accounted for before autonomous rotorcraft can be considered as reliable enough to have commonplace usage. In this paper we will describe the problem, analyze the required performance, present perception hardware and real-time algorithms.