Comparison of Autonomous Flight Control Performance Between Partial- and Full-Authority Helicopters

A comparison of a guidance and flight control system performance on a partial-authority helicopter was made against a previously flown version on a full-authority helicopter. This control system was integrated and flight-tested on a partial-authority helicopter to autonomously navigate and reactively avoid obstacles enroute and on final landing approach. Because both systems used virtually the same control system and aircraft, a comparison was performed to investigate how much of the autonomous maneuvering capability could be recovered using a partial-authority aircraft. This paper describes the control system, its performance, and how it was adapted to a partial-authority EH-60L Black Hawk helicopter. A partial-authority mixing method is described and it was used to integrate the autonomy system using frequency allocation to distribute the control commands to the high- and low-frequency actuation. Flight tests results are presented of the integrated system flying predefined maneuvers that ranged from precision hover maneuvers to moderately aggressive forward flight maneuvers. Results are also presented of the system navigating through mountainous terrain using a reactive obstacle-avoidance algorithm. Tracking performance, actuator usage, and stability results for both systems are shown. The comparison of the partial- and full-authority results showed that the partial-authority mixing system was effective by allowing the partial-authority system to achieve most of the full-authority performance as measured by path tracking error and actuator usage for several autonomous maneuvers.