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The Federal Aviation Administration (FAA) has been mandated by the Congressional funding bill of 2012 to open the National Airspace System (NAS) to Unmanned Aircraft Systems (UAS). With the growing use of unmanned systems, NASA has established a multi-center \"UAS Integration in the NAS\" Project, in collaboration with the FAA and industry, and is guiding its research efforts to look at and examine crucial safety concerns regarding the integration of UAS into the NAS. Key research efforts are addressing requirements for detect-and-avoid (DAA), self-separation (SS), and collision avoidance (CA) technologies. In one of a series of human-in-the-loop experiments, NASA Langley Research Center set up a study known as Collision Avoidance, Self-Separation, and Alerting Times (CASSAT). The first phase assessed active air traffic controller interactions with DAA systems and the second phase examined reactions to the DAA system and displays by UAS Pilots at a simulated ground control station (GCS). Analyses of the test results from Phase I and Phase II are presented in this paper. Results from the CASSAT study and previous human-in-the-loop experiments will play a crucial role in the FAA's establishment of rules, regulations, and procedures to safely, efficiently, and effectively integrate UAS into the NAS.

This article is from Sensors (Basel, Switzerland) , volume 12 . Abstract The accurate perception of the surroundings of a vehicle has been the subject of study of numerous automotive researchers for many years. Although several projects in this area have been successfully completed, very few prototypes have actually been industrialized and installed in mass produced cars. This indicates that these research efforts must continue in order to improve the present systems. Moreover, the trend to include communication systems in vehicles extends the potential of these perception systems transmitting their information via wireless to other vehicles that may be affected by the surveyed environment. In this paper we present a forward collision warning system based on a laser scanner that is able to detect several potential danger situations. Decision algorithms try to determine the most convenient manoeuvre when evaluating the obstacles’ positions and speeds, road geometry, etc. Once detected, the presented system can act on the actuators of the ego-vehicle as well as transmit this information to other vehicles circulating in the same area using vehicle-to-vehicle communications. The system has been tested for overtaking manoeuvres under different scenarios and the correct actions have been performed.

The USAF's F-16 Automatic Ground Collision Avoidance System (Auto GCAS) uses a single pre-planned roll to wings- level and 5-g pull-up to meet the operational requirements of being both aggressive and timely, meaning that extremely agile avoidance maneuvers will be executed at the last second to avoid the ground. There currently exists no similar Auto GCAS for manned military heavy' aircraft with lower climb performance such as transport, tanker, or bomber aircraft. This research proposes a new optimal control approach to the ground collision avoidance problem for heavy aircraft by mapping the aggressive and timely requirements of the automatic recovery to an optimal control formulation which includes lateral maneuvers around terrain. Results are presented for representative heavy aircraft scenarios against 3-D digital terrain, which are then compared to a Multi-Trajectory Auto GCAS with ve pre-planned maneuvers. Metrics were developed to quantify the improvement from using an optimal approach versus the pre-planned maneuvers. The research results provide a basis to evaluate the expected performance of any future Auto GCAS for all aircraft.

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This paper presents a scalable method to efficiently search for the most likely state trajectory leading to an event given only a simulator of a system. Our approach uses a reinforcement learning formulation and solves it using Monte Carlo Tree Search (MCTS). The approach places very few requirements on the underlying system, requiring only that the simulator provide some basic controls, the ability to evaluate certain conditions, and a mechanism to control the stochasticity in the system. Access to the system state is not required, allowing the method to support systems with hidden state. The method is applied to stress test a prototype aircraft collision avoidance system to identify trajectories that are likely to lead to near mid-air collisions. We present results for both single and multi-threat encounters and discuss their relevance. Compared with direct Monte Carlo search, this MCTS method performs significantly better both in finding events and in maximizing their likelihood.

G-induced loss of consciousness (G-LOC) is a pilot human factors (HF) problem that plagues all air forces that fly high performance fighter aircraft. Spatial disorientation (SD) is an even more serious HF problem that affects not only the military but also commercial aviation. By some estimates, one out of every four aircraft mishaps is due to a HF problem, and the pilot flies a perfectly operating aircraft into the terrain. Altitude warning systems and other voice or buzzer devices in the cockpit have been relatively ineffective at reducing the number of mishaps. To stem the tremendous loss of pilots and aircraft because of HF-related mishaps, the U.S. Air Force and Russian Air Force have developed automated collision avoidance systems. The U.S. Air Force has developed a Ground Collision Avoidance System (GCAS) that is automatic and requires no pilot intervention. The philosophy behind this system is reliability, pilot unobtrusiveness, and invisibility. The Russians also have developed a pilot state monitoring system that is automatic, but includes the pilot in its control loop. The Russian system even includes an onboard video camera that allows ground operators to observe the pilot during the mission. The objective of this paper is to discuss these two automated collision avoidance systems and to distinguish between the roles of the humans versus machines in each one. (4 figures, 6 refs.)

The Phase 1 DAA Minimum Operational Performance Standards (MOPS) provided requirements for two classes of DAA equipment: equipment Class 1 contains the basic DAA equipment required to assist a pilot in remaining well clear, while equipment Class 2 integrates the Traffic Alert and Collision Avoidance (TCAS) II system. Thus, the Class 1 system provides RWC functionality only, while the Class 2 system is intended to provide both RWC and Collision Avoidance (CA) functionality, in compliance with the Minimum Aviation System Performance (MASPS) for the Interoperability of Airborne Collision Avoidance Systems. The FAAs TCAS Program Office is currently developing Airborne Collision Avoidance System X (ACAS X) to support the objectives of the Federal Aviation Administrations (FAA) Next Generation Air Transportation System Program (NextGen). ACAS X has a suite of variants with a common underlying design that are intended to be optimized for their intended airframes and operations. ACAS Xu being is designed for UAS and allows for new surveillance technologies and tailored logic for platforms with different performance characteristics. In addition to Collision Avoidance (CA) alerting and guidance, ACAS Xu is being tuned to provide RWC alerting and guidance in compliance with the SC 228 DAA MOPS. With a single logic performing both RWC and CA functions, ACAS Xu will provide industry with an integrated DAA solution that addresses many of the interoperability shortcomings of Phase I systems. While the MOPS for ACAS Xu will specify an integrated DAA system, it will need to show compliance with the RWC alerting thresholds and alerting requirements defined in the DAA Phase 2 MOPS. Further, some functional components of the ACAS Xu system such as the remote pilots displayed guidance might be mostly references to the corresponding requirements in the DAA MOPS. To provide a seamless, integrated, RWC-CA system to assist the pilot in remaining well clear and avoiding collisions, several issues need to be addressed within the Phase 2 SC-228 DAA efforts. Interoperability of the RWC and CA alerting and guidance, and ensuring pilot comprehension, compliance and performance, will be a primary research area.

This registration corresponds to a Systematic Literature Review (SLR) conducted as a preliminary step within a broader research study. The sole purpose of this SLR is to systematically identify and retrieve high-quality and relevant academic publications related to Maritime Collision Prevention Systems (MCPS) that try to implement COLREGs (International Regulations for Preventing Collisions at Sea). The aim is not to perform a comprehensive review or meta-analysis of the findings presented in these studies, but rather to apply the structured and transparent methodology of an SLR to ensure a rigorous and unbiased selection of sources for subsequent analysis. All methodological details, including search strategies, inclusion/exclusion criteria, and data management procedures, are documented in this registration to ensure transparency and reproducibility.

This report was done on behalf of the Defense Safety Oversight Council Aviation Safety Improvements Task Force, Safety Technology Working Group. This study concludes that implementation of Automatic Collision Avoidance Systems (Auto-CAS) in F-16, F/A-18, F/A-22, and F-35 aircraft would save aircrew lives and preserve, and enhance combat capability.

This paper describes a Modeling and Simulation of an Unmanned Aircraft Systems (UAS) Collision Avoidance System, capable of representing different types of scenarios for UAS collision avoidance. Commercial and military piloted aircraft currently utilize various systems for collision avoidance such as Traffic Alert and Collision A voidance System (TCAS), Automatic Dependent Surveillance-Broadcast (ADS-B), Radar and ElectroOptical and Infrared Sensors (EO-IR). The integration of information from these systems is done by the pilot in the aircraft to determine the best course of action. In order to operate optimally in the National Airspace System (NAS) UAS have to work in a similar or equivalent manner to a piloted aircraft by applying the principle of "detect-see and avoid" (DSA) to other air traffic. Hence, we have taken these existing sensor technologies into consideration in order to meet the challenge of researching the modeling and simulation of an approximated DSA system. A Schematic Model for a UAS Collision Avoidance System (CAS) has been developed ina closed loop block diagram for that purpose. We have found that the most suitable software to carry out this task is the Satellite Tool Kit (STK) from Analytical Graphics Inc. (AGI). We have used the Aircraft Mission Modeler (AMM) for modeling and simulation of a scenario where a UAS is placed on a possible collision path with an initial intruder and then with a second intruder, but is able to avoid them by executing a right tum maneuver and then climbing. Radars have also been modeled with specific characteristics for the UAS and both intruders. The software provides analytical, graphical user interfaces and data controlling tools which allow the operator to simulate different conditions. Extensive simulations have been carried out which returned excellent results.

Automatic Ground Collision Avoidance Systems (Auto-GCAS) utilizes Digital Terrain Elevation Data (DTED) stored onboard a plane to determine potential recovery maneuvers. Because of the current limitations of computer hardware on military airplanes such as the F-22 and F-35, the DTED must be compressed through a lossy technique called binary-tree tip-tilt. The purpose of this study is to determine the accuracy of the compressed data with respect to the original DTED. This study is mainly interested in the magnitude of the error between the two as well as the overall distribution of the errors throughout the DTED. By understanding how the errors of the compression technique are affected by various factors (topography, density of sampling points, sub-sampling techniques, etc.), modifications can be made to the compression technique resulting in better accuracy. This, in turn, would minimize unnecessary activation of A-GCAS during flight as well as maximizing its contribution to fighter safety.

Topics: Federal Aviation Administration time/frequency - collision avoidance program; Relationship of time/frequency - CAS to future T/F systems; Brief review of the collision avoidance problem and discussion of time/frequency - CAS ground station factors; Remarks on World-Wide Time Synchronization by VLF; Precise time and time interval (PTTI) activities and plans (USAF); Discussion of synchronization by transportable clocks; Use of loran-C for timing; Loran-C/D systems concept; Timing potential of loran-C/D; Navy time/frequency programs; Application of time/frequency techniques in military station keeping; Satellite synchronization; Satellite tracking and data acquisition (STADAN) frequency combiner and microelectronic clock; Astrodata timing; GEOS time synchronization; ATS time synchronization; Satellite synchronization techniques; World-wide time review; Remarks on the application of RF spectroscopy of stores ions to frequency standards.

An analysis was performed to predict the effects of the Traffic Alert and Collision Avoidance System (TCAS III) on the performance of the Air Traffic Control Radar Beacon System (ATCRBS) in the Los Angeles Basin. This was accomplished by comparing the effects of TCAS III and TCAS II operations on airborne transponder and ground-based ATCRBS interrogator performance in the same hypothetical peak Los Angeles Basin aircraft deployment. (Author)

This report reviews the essential considerations in the design of anti-collision systems for use in road traffic, in terms of the expected effects on driver behavior and, consequently, on traffic safety. The two critical questions that should be answered before any CAS could function in a sensible way are: (1) What is the criterion for system activation? (2) What action will subsequently have to be performed? Different criteria for activation, while all in temporal terms, will give rise to different rates of alarms and of false alarms. A priori calculations are given for fixed time criteria, time-to- collision criteria, and worst-case criteria. A time-to-collision criterion must a priori be judged to be most adapted to 'natural' driving behavior. With respect to the actual action to be undertaken, the choice is among different levels of system take-over, where the variation is from 'none' to 'total'. Keywords: Netherlands, Collision avoidance, Behavior, Land transportation, Traffic.

Unmanned aircraft systems (UAS) will be required to equip with a detect-­‐and-­‐avoid (DAA) system in order to satisfy the federal aviation regulations to maintain well clear of other aircraft, some of which may be equipped with a Traffic Collision Avoidance System (TCAS) to mitigate the possibility of mid-­‐air collisions. As such, the minimum operational performance standards (MOPS) for UAS DAA systems are being designed with TCAS interoperability in mind by a group of industry, government, and academic institutions named RTCA Special Committee-228 (SC-228). This document will discuss the development of the spatial-­‐temporal volume known as the collision avoidance region in which the DAA system is not allowed to provide vertical guidance to maintain or regain DAA well clear that could conflict with resolution advisories (RAs) issued by the intruder aircraft's TCAS system. Three collision avoidance region definition candidates were developed based on the existing TCAS RA and DAA alerting definitions. They were evaluated against each other in terms of their interoperability with TCAS RAs and DAA alerts in an unmitigated factorial encounter analysis of 1.3 million simulated pairs.

Two different aspects of formation control of multiple agents subjected to linear transformation have been addressed in this paper. We consider a set of complex single integrator systems so that the dimension of the system reduces to half as opposed to the vector representation in Cartesian coordinate system. We first design a stable formation controller in an attempt to solve the formation control turned to stabilization problem and then find a collision avoidance controller in the transformed domain, respectively. Different linear transformations are used to facilitate the formation control task in a different way. For example Jacobi transformation is used to separate the shape control and trajectory control. The inverse of the transformation must have nonzero eigenvalues with both positive and negative real parts which may lead the system to instability. If the inverse of the transformation appears in closed loop then a diagonal stabilizing matrix is required to reassign the eigenvalues of the inverse of transformation in the right half of complex plane. The algorithm to find such stabilizing matrix is provided. We then define a matrix of potential in the actual domain which is the stepping stone to find a matrix of potential in the transformed domain. Thus collision avoidance controller can be designed directly in the transformed domain. The mathematical proof is given that both the actual and transformed system behaves identically. Simulation results are provided to support our claim.