NASA, the Federal Aviation Administration (FAA), General Atomics Aeronautical Systems (GA-ASI) and Honeywell International Inc. have successfully demonstrated a proof-of-concept sense-and-avoid (SAA) system, marking a major milestone to inform the development of standards and regulations to safely integrate Unmanned Aircraft Systems (UAS) in the National Airspace System (NAS). The results of this demonstration will aid in the development of the FAA’s Airborne Collision Avoidance System For Unmanned Aircraft (ACAS Xu) and contribute to the broader UAS community.
According to UAS-NAS project manager Laurie Grindle, “Our team is working toward solving our common goal of overcoming the challenges of integrating UAS into the National Airspace System; a topic that has increasingly proved its relevance as several industries across the country identify the need to fly UAS. Completing these recent flight tests has brought us one more step toward accomplishing that goal.”
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GA-ASI worked with NASA’s Armstrong Flight Research Center to integrate the new system aboard NASA’s Ikhana research aircraft, a civilian version of the company’s Predator B. The flight-test campaign in November and December 2014 evaluated the SAA system in a wide variety of collision-avoidance and self-separation encounters between two remotely piloted aircraft and various manned aircraft and included a sensor fusion algorithm being developed by Honeywell.
“GA-ASI is proud to continue development of SAA technology with NASA, the FAA, and our industry partners,” said Frank Pace, president, Aircraft Systems, GA-ASI. “This public-private collaboration has achieved an important step for the safe and efficient integration of UAS into civilian airspace by leveraging NASA’s unique test capabilities and the FAA’s novel collision avoidance technology.”
Initial SAA flight tests successfully demonstrated both the automatic collision avoidance system as well as pilot-in-the-loop self-separation functionality for UAS. Over the course of five weeks, nine flights were conducted. The team flew 170 encounters and collected over 50 hours of flight data with notable accomplishments. These flight tests marked the first time that a UAS collision avoidance system was tested without artificial horizontal and vertical offsets applied to the algorithm as the air-to-air encounters were flown in actual conflict conditions. These flights were also the first time that a coordinated automatic response was employed by a UAS to resolve collision avoidance conflicts. In addition, tests involving Armstrong’s Ikhana and a GA-owned Predator B marked the first air-to-air collision avoidance encounters between two UAS.
Objectives of this effort included evaluation of the performance of ACAS Xu collision avoidance algorithms against air traffic using both legacy Traffic Collision Avoidance System (TCAS II) messages and proof of concept Automatic Dependent Surveillance-Broadcast (ADS-B) messages. For these tests, air traffic designated as a non-cooperative intruder was tracked using an air-to-air radar system developed by GA-ASI. ACAS Xu is the first collision avoidance function designed explicitly for UAS. It can be matched to aircraft performance and is designed to be fully interoperable with future ACAS X variants as well as with legacy systems such as the TCAS II currently used on most commercial transport aircraft.
Researchers evaluated three self-separation displays and algorithms and their ability to effectively inform the UAS pilot of nearby traffic and help resolve conflicts in a timely manner. These flight tests also validated airborne radar and ADS-B surveillance simulation models on sensor performance and uncertainties to help determine the effects of these parameters and environmental conditions on self-separation algorithm’s performance. Flight-testing of collision-avoidance and self-separation technology contributes to ongoing work to develop a technical standard for a sense/detect-and-avoid system for UAS.
For more about NASA Armstrong Flight Research Center, visit www.nasa.gov/centers/armstrong
Filed Under: Aerospace + defense