The Generic Resolution Advisor and Conflict Evaluator (GRACE) for Detect-And-Avoid (DAA) Systems

Abramson, Michael J.; Refai, Mohamad; Santiago, Confesor

doi:10.2514/6.2017-4485

Cited by 23 publications

(14 citation statements)

References 28 publications

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“…18 The encounters between UAS and VFR aircraft were simulated using SAA Control, a client of the Java Architecture for DAA Extensibility and Modeling (JADEM). 24 JADEM employs a model of a DAA system that provides functions to evaluate potential LoDWC, to declare a DAA alert, and to optionally execute a maneuver to avoid predicted LoDWC. In this study, both the UAS trajectories and the actual VFR flight tracks were played back from files to create encounters.…”

Section: Iva Aces Generated Encountersmentioning

confidence: 99%

“…[4][5][6][7] Prototype DAA algorithms have also been developed to alerting and guidance research. [8][9][10] These developments enabled the RTCA Special Committee 228 (SC-228) to publish the Minimum Operational Performance Standards (MOPS) for DAA systems 11 and air-to-air radar 12 in 2017. The corresponding Technical Standard Orders (TSO), TSO-C211 and TSO-C212, were published by the Federal Aviation Administration (FAA) in October 2017.…”

Section: Introductionmentioning

confidence: 99%

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Well Clear Trade Study for Unmanned Aircraft System Detect And Avoid with Non-Cooperative Aircraft

Cone

Lee

et al. 2018

2018 Aviation Technology, Integration, and Operations Conference

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This paper presents a process for selecting candidate Detect-and-Avoid Well Clear definitions for Unmanned Aircraft Systems and non-cooperative aircraft. The selection is based on considerations of the unmitigated collision risk, maneuver initiation range, and others. Operational assumptions related to low cost, size, weight, and power sensors equipped by the Unmanned Aircraft Systems are applied to set the scope of aircraft performance and drive metrics computation. Four candidate Well Clear definitions, two primary and two secondary, varying from 1500 to 2500 ft in their horizontal miss distance and from 0 to 25 sec in modified tau, are selected for future analyses.

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Section: Iva Aces Generated Encountersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Well Clear Trade Study for Unmanned Aircraft System Detect And Avoid with Non-Cooperative Aircraft

Cone

Lee

et al. 2018

2018 Aviation Technology, Integration, and Operations Conference

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“…This study used a fast-time simulation with a generic resolver developed at NASA as a DAA system. 9 The simulation includes a model for selecting a maneuver from the guidance options offered and a model for pilot delays associated with evaluating and executing maneuvers in this domain. Aircraft were modeled using a kinematic trajectory generator that accepts aircraft performance constraints and produces trajectories that satisfy those constraints.…”

Section: B Simulation Platformmentioning

confidence: 99%

UAS Well Clear Recovery against Non-Cooperative Intruders using Vertical Maneuvers

Cone

Thipphavong

Lee

et al. 2017

17th AIAA Aviation Technology, Integration, and Operations Conference

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This paper documents a study that drove the development of a mathematical expression in the detect-and-avoid (DAA) minimum operational performance standards (MOPS) for unmanned aircraft systems (UAS). This equation describes the conditions under which vertical maneuver guidance should be provided during recovery of DAA well clear separation with a non-cooperative VFR aircraft. Although the original hypothesis was that vertical maneuvers for DAA well clear recovery should only be offered when sensor vertical rate errors are small, this paper suggests that UAS climb and descent performance should be considered-in addition to sensor errors for vertical position and vertical rate-when determining whether to offer vertical guidance. A fast-time simulation study involving 108,000 encounters between a UAS and a non-cooperative visual-flight-rules aircraft was conducted. Results are presented showing that, when vertical maneuver guidance for DAA well clear recovery was suppressed, the minimum vertical separation increased by roughly 50 feet (or horizontal separation by 500 to 800 feet). However, the percentage of encounters that had a risk of collision when performing vertical well clear recovery maneuvers was reduced as UAS vertical rate performance increased and sensor vertical rate errors decreased. A class of encounter is identified for which vertical-rate error had a large effect on the efficacy of horizontal maneuvers due to the difficulty of making the correct left/right turn decision: crossing conflict with intruder changing altitude. Overall, these results support logic that would allow vertical maneuvers when UAS vertical performance is sufficient to avoid the intruder, based on the intruder's estimated vertical position and vertical rate, as well as the vertical rate error of the UAS' sensor. * mod  = modified tau threshold I. Introduction AFE integration of unmanned aircraft systems (UAS) into the U.S. National Airspace System (NAS) requires that they interoperate with existing safety systems for manned aircraft. One requirement that is particularly difficult for UAS to satisfy is the requirement for aircraft to perform see-and-avoid to remain "well clear" of other aircraft. 1 This requirement is in the FAA's Federal Aviation Regulation §91.113(b), which dictates that, "When weather conditions permit, regardless of whether an operation is conducted under instrument flight rules or visual flight rules, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft. When a rule of this section gives another aircraft the right of way, the pilot shall give way to that aircraft and may not pass over, under, or ahead of it unless well clear." §91.113 also covers right-of-way rules for air vehicle operations. If two aircraft get too close and lose "well clear," they are expected to maneuver immediately and attempt to regain it. However, the exact definition of the term "well clear" is not given in the regulations, and is subject to interpretation by the pilot. This is diffi...

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“…To account for this, researchers developed guidance to regain DAA well clear. Guidance to regain DAA well clear would engage at any point that a loss of DAA well clear could not be avoided and would highlight a narrow range of headings or altitudes/vertical speeds to achieve in order to maximize separation at the closest point of approach (CPA) between own ship and the intruder [12]. DAA maneuver guidance could then be distinguished by when in an encounter it is issued: guidance to remain DAA well clear when DAA well clear can still be maintained, and guidance to regain DAA well clear when DAA well clear is to be recovered.…”

Section: Daa Alerting and Guidancementioning

confidence: 99%

“…The Java Architecture for DAA Modeling and Extensibility (JADEM), developed at NASA Ames Research Center, generated the DAA system alerts and maneuver guidance [12]. JADEM references a configurable DAA well clear definition in order to determine if traffic within its simulated sensor ranges satisfy various alert criteria.…”

Section: Experimental Daa Systemmentioning

confidence: 99%

An Interoperability Concept for Detect and Avoid and Collision Avoidance Systems: Results from a Human-in-the-Loop Simulation

Rorie

Fern

2018

2018 Aviation Technology, Integration, and Operations Conference

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The integration of Unmanned Aircraft Systems (UAS) into the National Airspace System (NAS) poses a variety of technical challenges to UAS developers and aviation regulators. In response to growing demand for access to civil airspace in the United States, the Federal Aviation Administration (FAA) has produced a roadmap identifying key areas requiring further research and development. One such technical challenge is the development of a "detect and avoid" system (DAA) capable of providing a means of compliance with the "see and avoid" requirement in manned aviation. The purpose of the DAA system is to support the pilot, situated at a ground control station (GCS), in maintaining "DAA well clear" of nearby aircraft through the use of GCS displays and alerts. In addition to its primary function of aiding the pilot in maintaining DAA well clear, the DAA system must also safely interoperate with existing NAS systems and operations, such as the airspace management procedures of air traffic controllers (ATC) and Collision Avoidance (CA) systems currently in use by manned aircraft, namely the Traffic Alert and Collision Avoidance System (TCAS II). It is anticipated that many UAS architectures will integrate both a DAA system and a TCAS II. It is therefore necessary to explicitly study the integration of DAA and TCAS II alerting structures and maneuver guidance formats to ensure that pilots understand the appropriate type and urgency of their response to the various alerts. This paper presents a concept of interoperability for the two systems. The concept was developed with the goal of avoiding any negative impact on the performance level of TCAS II while retaining a DAA system that still effectively enables pilots to maintain DAA well clear. The interoperability concept described in the paper focuses primarily on facilitating the transition from a latestage DAA encounter (where a loss of DAA well clear is imminent) to a TCAS II Corrective Resolution Advisory (RA), which requires pilot compliance within five seconds of its issuance. The interoperability concept was presented to 10 participants (6 active UAS pilots and 4 active commercial pilots) in a medium-fidelity, human-in-the-loop simulation designed to stress different aspects of the DAA and TCAS II systems. Pilots' ability to maintain separation, their rate of compliance and response times using the interoperability concept are reported. Results indicated that pilots exhibited comprehension of, and appropriate prioritization within, the DAA-TCAS II combined alert structure. Pilots demonstrated a high rate of compliance with TCAS II RAs and were also seen to respond to corrective RAs within the five second requirement established for manned aircraft. The DAA system presented under test was also shown to be effective in supporting pilots' ability to maintain DAA well clear in the overwhelming majority of cases in which pilots had sufficient time to respond.

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The Generic Resolution Advisor and Conflict Evaluator (GRACE) for Detect-And-Avoid (DAA) Systems

Cited by 23 publications

References 28 publications

Well Clear Trade Study for Unmanned Aircraft System Detect And Avoid with Non-Cooperative Aircraft

Well Clear Trade Study for Unmanned Aircraft System Detect And Avoid with Non-Cooperative Aircraft

UAS Well Clear Recovery against Non-Cooperative Intruders using Vertical Maneuvers

An Interoperability Concept for Detect and Avoid and Collision Avoidance Systems: Results from a Human-in-the-Loop Simulation

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