Research and Product Testing of NASA ADS-B Detect-and-Avoid AlgorithmLead by Ricardo Arteaga, CxP Orion Flight Systems Engineer at NASA Dryden, the research team based out of the NASA Armstrong Flight Research Center in Edwards, California recently published a research document titled “Application of an ADS-B Sense and Avoid Algorithm,” discussing the testing of their patented (Patent #9,405,005) ADS-B, sense and avoid, avionics software. The software, exclusively licensed by Vigilant Aerospace Systems, outlined in the document provides the foundation for our FlightHorizon detect and avoid avionics software for manned and unmanned aircraft systems. As this research has great implications for the future of sense-and-avoid technology in the national airspace, we’ve shared some highlights from the research document below. Below is a brief summary with excerpts explaining what this research means for the future of unmanned systems integrations into the national airspace. Read the full 20-page document: Application of an ADS-B Sense and Avoid Algorithm_AFRC-E-DAA-TN30918_20160007770 [PDF]
Benefits of ADS-BAutomatic Dependent Surveillance-Broadcast (ADS-B) improves on current radar-based systems by providing more precise tracking and faster transmitting. According to research, “[ADS-B] tracks aircraft position with a much higher resolution and lower error rate [than existing radar-based systems].” ADS-B can be broken into two categories: ADS-B Out and ADS-B In. “ADS-B Out refers to the broadcast of ownship state information of an appropriately equipped aircraft. ADS-B In refers to the ability of an appropriately equipped aircraft to receive and display ADS-B information from other aircraft.” Typically, ADS-B systems rate a navigation accuracy category (NACp) ADS-B accuracy parameter of 8 or 9 rather than the standard radar systems which typically rate at a NACp of 6 or 7. Also, ADS-B systems have less physical and mechanical drawbacks allowing for more information to transmit more efficiently: “Without the mechanical constraints of radar-based systems, ADS-B systems can update an aircraft state much faster (typically 1Hz, instead of once every 12 seconds).”
Important Regulatory Notes for Next Generation Air Traffic Control Systems (ATC)
- As of January 2020, the U.S. Federal Aviation Administration (FAA) has mandated that all aircraft operating within the National Airspace System (NAS) class A airspace must be equipped with ADS-B Out technology. See the FAA FAQs page for more information on this regulation.
Sense and Avoid Sub-Functions of SystemFrom document: Table 2. Sense and avoid sub-functions
|Detect:||Detect presence of aircraft in vicinity of UAS|
|Track:||Estimate position and velocity (state) of intruders based on one or more surveillance reports|
|Evaluate:||Assess collision risk based on intruder and UAS states|
|Prioritize:||Prioritize intruder tracks based on a collision risk threshold|
|Declare:||Decide that action is needed|
|Determine:||Determine what action is required|
|Command:||Communicate determined action to UAS|
|Execute:||Execute the determined action|
Sense and Avoid System Pilot UsabilityBefore conducting a live test of the sense and avoid software, a simulation tool was designed into the software to allow for NASA pilots to test and score the user performance and experience of working with the software. The test was conducted on a range of pilots including a fighter pilot, large transport pilot, general aviation pilot, and unmanned aircraft vehicle pilot. “Each pilot was asked to fly an encounter scenario, such as the scenario shown in Fig. 7, in this simulated environment after having received minimal instructions on how to use the software. Each encounter scenario had at least one future loss of separation in the horizontal or vertical dimension. At the onset of the simulation, the two aircraft were on a direct collision course.” After running the simulation, each pilot rated the software on the usefulness, accuracy, timeliness of the RAs as well as the pilot response time (general ability to follow the visual and aural cues). The table below shows the results of the pilot usability test.
Real-Time Environment Sense and Avoid System Test with Cessna 172On August 3, 2015, NASA conducted a “proof of concept flight of the [sense and avoid software] display system.” An instructor pilot flew a training mission in a Cessna 172 manned aircraft equipped with and recording ADS-B In surveillance data. During this real-time flight test, the ADS-B system recorded two surveillance targets (aircrafts in range), which were detected and tracked in real-time. This demonstration validated that the system was receiving and displaying the (a) relative horizontal position, (b) ground speed, (c) heading (directionality or track angle), (d) pressure altitude of airborne traffic relative to ownship, (e) vertical trend of airborne traffic, (f) air/ground status of aircrafts, and (g) flight ID (ICAO code).
- NASA Technical Reports Server (NTRS): “Application of an ADS-B Sense and Avoid Algorithm”; Document ID: 20160007770.
- For more information on ADS-B systems, check out this excellent resource page from the FAA on Automatic Dependent Surveillance-Broadcast (ADS-B).
Vigilant Aerospace is the leading developer of detect-and-avoid and airspace management software for uncrewed aircraft systems (UAS or drones). The company’s product, FlightHorizon, is based on two NASA patents and uses data from multiple sources to display a real-time picture of the air traffic around a UAS and to provide automatic avoidance maneuvers to prevent collisions. The software is designed to meet industry technical standards, to provide automatic safety and to allow UAS to safely fly beyond the sight of the pilot. The software has won multiple industry awards and the company has had contracts and users at NASA, the FAA, the U.S. Department of Defense and with a variety of drone development programs. Visit our website at www.VigilantAerospace.com