Publications

Refine Results

(Filters Applied) Clear All

Tagged As

Electro-optical system analysis for sense and avoid

August 18, 2008
  |
Conference Paper
Author:
John Daniel Griffith
…
Published in:
AIAA Guidance, Navigation, and Control Conf. and Exhibit, 19-21 August 2008.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This paper presents a parametric analysis of the sense and avoid capability for an electro- optical system on unmanned aircraft. Our sensor analysis is based on simulated encounters from a new U.S. airspace encounter model that provides a comprehensive distribution of typical visual flight rule (VFR) aircraft behavior and encounter geometries. We assess the exchange between the sensor field-of-view shape and detection range with the probability of intruder detection prior to near miss. This assessment also includes a trade-off analysis between field-of-view azimuth angle and probability of detection with fixed tracking technology (i.e. pixel array sensor and tracking algorithm). Initial results suggest that current standards are suitable for detecting larger aircraft but may not be ideal for small aircraft such as ultralights.
READ LESS

Summary

This paper presents a parametric analysis of the sense and avoid capability for an electro- optical system on unmanned aircraft. Our sensor analysis is based on simulated encounters from a new U.S. airspace encounter model that provides a comprehensive distribution of typical visual flight rule (VFR) aircraft behavior and encounter...

READ MORE
Electro-optical system analysis for sense and avoid

Hazard alerting using line-of-sight rate

August 18, 2008
  |
Conference Paper
Author:
Mykel J. Kochenderfer
…
Published in:
AIAA Guidance, Navigation, and Control Conf., 18-21 August 2008.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This paper presents an analysis of an electro-optical hazard alerting system based on intruder line-of-sight rate. We use a recently-developed airspace encounter model to analyze intruder line-of-sight rate behavior prior to near miss. We look at a simple hazard alerting system that alerts whenever the line-of-sight rate drops below some set threshold. Simulations demonstrate that such an approach, regardless of the chosen threshold, leads to frequent false alerts. We explain how the problem of hazard alerting can also be formulated as a partially observable Markov decision process (POMDP) and show how such an approach significantly decreases the false alert rate.
READ LESS

Summary

This paper presents an analysis of an electro-optical hazard alerting system based on intruder line-of-sight rate. We use a recently-developed airspace encounter model to analyze intruder line-of-sight rate behavior prior to near miss. We look at a simple hazard alerting system that alerts whenever the line-of-sight rate drops below some...

READ MORE
Hazard alerting using line-of-sight rate

Encounter modeling for sense and avoid deployment

May 5, 2008
  |
Conference Paper
Author:
Mykel J. Kochenderfer
…
Published in:
2008 Integrated Communications, Navigation, and Surveillence Conf., 5-7 May 2008.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

Integrating unmanned aircraft into civil airspace requires the development and certification of systems for sensing and avoiding other aircraft. Because such systems are typically very complex and a high-level of safety must be maintained, rigorous analysis is required before they can be certified for operational use. As part of the certification process, collision avoidance systems need to be evaluated across millions of randomly generated close encounters that are representative of actual operations. New encounter models are under development that capture changes that have occurred in U.S. airspace since earlier models were developed in the 1980s and 1990s. These models capture the characteristics of small, General Aviation aircraft that may not be receiving Air Traffic Control services as well as typically larger aircraft that are squawking a discrete transponder code. Both models allow dynamic changes in airspeed, vertical rates, and turn rates in a way that was not possible previously. This paper describes the process used to construct the encounter models, how the models may be used in the development of sense-and-avoid systems for unmanned aircraft, and their application in an analysis of an electro-optical system for collision avoidance.
READ LESS

Summary

Integrating unmanned aircraft into civil airspace requires the development and certification of systems for sensing and avoiding other aircraft. Because such systems are typically very complex and a high-level of safety must be maintained, rigorous analysis is required before they can be certified for operational use. As part of the...

READ MORE
Encounter modeling for sense and avoid deployment

Analysis of ground surveillance assets to support Global Hawk airspace access at Beale Air Force Base

August 10, 2007
  |
Project Report
Author:
Randall T. Wiken
…
Published in:
Project Report ATC-335, MIT Lincoln Laboratory
Topic:
air traffic control
R&D area:
R&D group:

Summary

This study, performed from May 2006 to January 2007 by MIT Lincoln Laboratory, investigated the feasibility of providing ground-sensor-based traffic data directly to Global Hawk operators at Beale AFB. The system concept involves detecting and producing tracks for all cooperative (transponder-equipped) and non-cooperative aircraft from the surface to 18,000 ft MSL, extending from the Beale AFB Class C airspace cylinder northward to the China Military Operations Area (MOA). Data from multiple sensors can be fused together to create a comprehensive air surveillance picture, with the altitudes of non-cooperative targets estimated by fusing returns from all available sensor data. Such a capability, if accepted by the FAA, could mitigate the need for Temporary Flight Restrictions (TFR) to satisfy Certificate of Waiver or Authorization (COA) requirements. There are no existing specifications for ground-sensor-based Unmanned Aerial Systems (UAS) traffic avoidance procedures, nor is it yet known how precisely altitude needs to be estimated. It may be possible to avoid traffic laterally, in which case traffic altitude need not be known accurately. If, however, it is necessary to also avoid traffic vertically, then altitudes will need to be estimated to some (as yet undefined) level of accuracy.
READ LESS

Summary

This study, performed from May 2006 to January 2007 by MIT Lincoln Laboratory, investigated the feasibility of providing ground-sensor-based traffic data directly to Global Hawk operators at Beale AFB. The system concept involves detecting and producing tracks for all cooperative (transponder-equipped) and non-cooperative aircraft from the surface to 18,000 ft...

READ MORE
Analysis of ground surveillance assets to support Global Hawk airspace access at Beale Air Force Base

The Traffic Alert and Collision Avoidance System

June 1, 2007
  |
Journal Article
Author:
James K. Kuchar
…
Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 277-296.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

The Traffic Alert and Collision Avoidance System (TCAS) has had extraordinary success in reducing the risk of mid-air collisions. Now mandated on all large transport aircraft, TCAS has been in operation for more than a decade and has prevented several catastrophic accidents. TCAS is a unique decision support system in the sense that it has been widely deployed (on more than 25,000 aircraft worldwide) and is continuously exposed to a high-tempo, complex air traffic system. TCAS is the product of carefully balancing and integrating sensor characteristics, tracker and aircraft dynamics, maneuver coordination, operational constraints, and human factors in time-critical situations. Missed or late threat detections can lead to collisions, and false alarms may cause pilots to lose trust in the system and ignore alerts, underscoring the need for a robust system design. Building on prior experience, Lincoln Laboratory recently examined potential improvements to the TCAS algorithms and monitored TCAS activity in the Boston area. Now the Laboratory is pursuing new collision avoidance technologies for unmanned aircraft.
READ LESS

Summary

The Traffic Alert and Collision Avoidance System (TCAS) has had extraordinary success in reducing the risk of mid-air collisions. Now mandated on all large transport aircraft, TCAS has been in operation for more than a decade and has prevented several catastrophic accidents. TCAS is a unique decision support system in...

READ MORE
The Traffic Alert and Collision Avoidance System

Improving the resolution advisory reversal logic of the traffic alert and collision avoidance system

October 15, 2006
  |
Conference Paper
Author:
Andrew D. Zeitlin
…
Published in:
25th IEEE/AIAA Digital Avionics Systems Conf., 15-18 October 2006, pp. 561-570.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

The Traffic Alert and Collision Avoidance System (TCAS II) is the worldwide standard system for manned aircraft to avoid collisions with airborne transponder-equipped traffic. A safety vulnerability of the collision avoidance logic was reported by European analysts, who also proposed a change to correct it. The safety issue concerns limitations in the ability of TCAS to reverse the sense of a Resolution Advisory (RA) during an encounter. The issue was addressed by a team of experts1 in the Requirements Working Group (RWG) of RTCA Special Committee 147 [1]. This paper discusses the problem, the metrics and methods used in the analysis, and presents results that quantify the effectiveness of the proposed solution. Finally, recommendations are presented for implementing the change.
READ LESS

Summary

The Traffic Alert and Collision Avoidance System (TCAS II) is the worldwide standard system for manned aircraft to avoid collisions with airborne transponder-equipped traffic. A safety vulnerability of the collision avoidance logic was reported by European analysts, who also proposed a change to correct it. The safety issue concerns limitations...

READ MORE
Improving the resolution advisory reversal logic of the traffic alert and collision avoidance system

Evaluation of proposed changes to the ACAS modified tau calculation

May 1, 2006
  |
Conference Paper
Author:
James K. Kuchar
Published in:
Int. Civil Aviation Organization Aeronautical Surveillance Panel Working Group, 1 May 2006.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

Modified tau is a parameter computed by ACAS to estimate the earliest time at which a collision could occur should an intruder aircraft accelerate toward the own aircraft. A concern with the modified tau calculation has been raised in a class of encounters where intruders are already close and converging slowly. In these problem cases, ACAS may induce a Near Mid-Air Collision by generating RAs with inappropriate timing or initial sense or failing to reverse sense when necessary. Performance in some problem encounters is greatly improved when using several proposed changes to the modified tau equations. These changes are outside CP112E, which focuses only on RA reversals. Although changes to modified tau resolve some problem encounters, aggregate risk-ratio results do not support implementing the existing proposals. There remains a concern about mid-air collision risk due to vulnerability in the existing modified tau equations, yet a robust solution to the problem has not been developed.
READ LESS

Summary

Modified tau is a parameter computed by ACAS to estimate the earliest time at which a collision could occur should an intruder aircraft accelerate toward the own aircraft. A concern with the modified tau calculation has been raised in a class of encounters where intruders are already close and converging...

READ MORE
Evaluation of proposed changes to the ACAS modified tau calculation

Update on the analysis of ACAS performance on Global Hawk

May 1, 2006
  |
Conference Paper
Author:
James K. Kuchar
Published in:
Int. Civil Aviation Organization Aeronautical Surveillance Panel Working Group, 1 May 2006.
Topic:
UAVs
R&D area:
R&D group:

Summary

Initial results are presented from a Lincoln Laboratory study of ACAS performance on the Global Hawk UAV. The study has been applying the process outlined in the ICAO ACAS Manual which involves developing UAV airspace encounter models and running fast-time Monte Carlo simulations of encounters. ACAS performance was examined in conventional aircraft vs. conventional aircraft, conventional aircraft vs. non-ACAS Global Hawk, and conventional aircraft vs. ACAS-equipped Global Hawk cases. The existing ICAO and ACASA encounter models were modified to reflect Global Hawk flight characteristics. ACAS performance on Global Hawk was also assessed parametrically across reaction latencies from 0 - 20 s. Global Hawk flight characteristics were shown to have a small but measurable negative impact on collision risk. Assuming no system failures or visual acquisition effects occur, performance with ACAS on Global Hawk is significantly better than without ACAS if response latencies (from the moment an RA is issued to the moment maneuvering begins) are less than 10 s. Performance drops off rapidly at latencies greater than 10 s. The needs for improved airspace models and a more in-depth study of the interaction between visual acquisition and ACAS are noted.
READ LESS

Summary

Initial results are presented from a Lincoln Laboratory study of ACAS performance on the Global Hawk UAV. The study has been applying the process outlined in the ICAO ACAS Manual which involves developing UAV airspace encounter models and running fast-time Monte Carlo simulations of encounters. ACAS performance was examined in...

READ MORE
Update on the analysis of ACAS performance on Global Hawk

Safety analysis methodology for unmanned aerial vehicle (UAV) collision avoidance systems

June 27, 2005
  |
Conference Paper
Author:
James K. Kuchar
Published in:
USA/Europe Air Traffic Management Seminar, 27-30 June 2005.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

The integration of Unmanned Aerial Vehicles (UAVs) into civil airspace requires new methods of ensuring collision avoidance. Concerns over command and control latency, vehicle performance, reliability of autonomous functions, and interoperability of sense-and-avoid systems with the Traffic Alert and Collision Avoidance System (TCAS) and Air Traffic Control must be resolved. This paper describes the safety evaluation process that the international community has deemed necessary to certify such systems. The process focuses on a statistically-valid estimate of collision avoidance performance developed through a combination of airspace encounter modeling, fast-time simulation of the collision avoidance system across millions of encounter scenarios, and system failure and event sensitivity analysis. Example simulation results are provided for an implementation of the analysis process currently being used to evaluate TCAS on the Global Hawk UAV.
READ LESS

Summary

The integration of Unmanned Aerial Vehicles (UAVs) into civil airspace requires new methods of ensuring collision avoidance. Concerns over command and control latency, vehicle performance, reliability of autonomous functions, and interoperability of sense-and-avoid systems with the Traffic Alert and Collision Avoidance System (TCAS) and Air Traffic Control must be resolved...

READ MORE
Safety analysis methodology for unmanned aerial vehicle (UAV) collision avoidance systems

Safety analysis process for the Traffic Alert and Collision Avoidance System (TCAS) and see-and-avoid systems on remotely piloted vehicles

September 20, 2004
  |
Conference Paper
Author:
James K. Kuchar
…
Published in:
AIAA 3rd Unmanned-Unlimited Technical Conf., 20-23 September 2004, pp. 1-13.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

The integration of Remotely Piloted Vehicles (RPVs) into civil airspace will require new methods of ensuring traffic avoidance. This paper discusses issues affecting requirements for RPV traffic avoidance systems and describes the safety evaluation process that the international community has deemed necessary to certify such systems. Alternative methods for RPVs to perform traffic avoidance are discussed, including the potential use of new see-and- avoid sensors or the Traffic Alert and Collision Avoidance System (TCAS). Concerns that must be addressed to allow the use of TCAS on RPVs are presented. The paper then details the safety evaluation process that is being implemented to evaluate the safety of TCAS on Global Hawk. The same evaluation process can be extended to other RPVs and traffic avoidance systems for which thorough safety analyses will also be required.
READ LESS

Summary

The integration of Remotely Piloted Vehicles (RPVs) into civil airspace will require new methods of ensuring traffic avoidance. This paper discusses issues affecting requirements for RPV traffic avoidance systems and describes the safety evaluation process that the international community has deemed necessary to certify such systems. Alternative methods for RPVs...

READ MORE
Safety analysis process for the Traffic Alert and Collision Avoidance System (TCAS) and see-and-avoid systems on remotely piloted vehicles
41-50 of 91