A collision avoidance algorithm for helicopter Flight Director and Surveillance System

The introduction of automated flight control and management systems have made possible aircraft designs that sacrifice arodynamic stability in order to incorporate stealth technology intro their shape, operate more efficiently, and are highly maneuverable. Therefore, modern flight management systems are reliant on multiple redundant sensors to monitor and control the rotations of the aircraft. To this end, a novel distributed quaternion Kalman filtering algorithm is developed for tracking the rotation and orientation of an aircraft in the three-dimensional space. The algorithm is developed to distribute computation among the sensors in a manner that forces them to consent to a unique solution while being robust to sensor and link failure, a desirable characteristic for flight management systems. In addition, the underlying quaternion-valued state space model allows to avoid problems associated with gimbal lock. The performance of the developed algorithm is verified through simulations.

The differences in performance of various manufacturers' Flight Management Systems (FMSs) and their associated Flight Management Computers (FMCs) have the potential for significant operational impact on the air traffic control system and as such need to be examined on a recurring basis. Performance-based navigation (PBN) is a fundamental principle for aircraft operations that will facilitate the transition to future airspace systems. A critical element of PBN is the FMS's capability to fly a consistently repeatable and predictable flight path trajectory that will meet the expectations of air traffic control. FMS manufacturers build their systems in accordance with and for area navigation systems, Technical Standard Orders and Advisory Circulars. Area Navigation (RNAV) and Required Navigation Performance (RNP) procedures and routes are published by the Federal Aviation Administration (FAA) according to criteria contained in FAA orders. It is anticipated that the resulting performance of the aircraft FMC will meet the procedure design requirements identified in the FAA criteria. Sometimes, due to the nearly independent development of procedure design criteria and aircraft performance standards, the paths of various aircraft on the same procedure do not coincide and therefore do not match the expectations of the procedure designer. These differences may result from any or all of the following: variations in FMC equipment installed on the aircraft; variations and errors in procedure coding in the FMC navigation database; variations in aircraft-to-FMC interface and associated aircraft performance capabilities; and variations in flight crew training and procedures. The hypothesis of this paper is that the FMCs built by avionics manufacturers and installed as the core of the FMC/FMS combinations in various airframe platforms perform differently and we will attempt to quantify those differences. This paper focuses on FMC performance when flying Standard Instrument Departures (SIDs) and their associated waypoints and leg types (path terminators) and combinations as described in. Public instrument procedures flown using RNAV equipment are used as the baseline for measuring the performance variations. Controlled field observations trials were made using twelve FMS test benches and three simulators at seven major FMC manufacturers and two airlines. Analysis of data from the trials confirms differences and the details are presented. The intent of this report is to contribute technical data as a foundation for the acceptance of required navigation performance (RNP) departures.

China has been gradually relaxing its ban on the use of low-altitude airspace across the country. To guarantee the high reliability of air traffic management (ATM), conflict detection and conflict resolution (CDR) approaches are indispensable to maintain safe separation between neighbouring small fixed-wing aircraft. In this study, we analyse a temporal and spatial integrated strategy for safety assessment purposes in opening the low-altitude urban airspace of Chinese pilot cities. First, we present a detailed mathematical description of the proposed algorithms based on a spatial grid partitioning system (SGPS). For our system, a conflict detection (CD) algorithm is designed to determine if two trajectories pass through the same grid space within overlapping time windows. A conflict resolution (CR) algorithm integrates a proposed time scheduling-based technique (TST) and vertical change-based technique (VCT), which operate under predetermined basic principles. Then, based on our novel CDR algorithms, a causal model is constructed in graphical modelling and analysis software (GMAS) to generate a state space that can provide a global perspective on scenario dynamics and better understanding of induced conflict occurrences. Finally, simulation results demonstrate that the proposed approach is practical and efficient.

The differences in performance of various manufacturers' Flight Management Systems (FMSs) and their associated Flight Management Computers (FMCs) have the potential for significant impact on the air traffic control system and as such need to be examined and reexamined. While Performance-Based Navigation (PBN), Area Navigation (RNAV) and Required Navigation Performance (RNP) procedures and routes are designed according to criteria contained in Federal Aviation Administration (FAA) orders, FMC manufacturers build their systems in accordance with Minimum Aviation System Performance Standards (MASPS) and Minimum Operational Performance Standards (MOPS) for area navigation systems, Technical Standard Orders (TSOs) and Advisory Circulars (ACs). With the exception of some minor differences, it has been shown in previous research on this subject that the resulting performance of the aircraft FMC will generally meet the procedure design requirements identified in the FAA criteria.

Conflict is inevitable to take place in collaborative design, and conflict resolution plays an important part in complex product collaborative design systems. Firstly, a mathematic description model in collaborative design considering resource conflict, process conflict and design conflict is given, and the mathematic model expresses the origin of conflict and shows that conflict resolution is a multiobjective planning problem. Next, a conflict resolution algorithm considering design objective optimization is presented, and fuzzy value and fuzzy grade are applied in the algorithm. Depending on both considering design variables having fundamental influences on its design objectives and the cost of conflict resolution, the algorithm can improve the quality and efficiency of conflict resolution. Finally, an example of single cylindrical gear reducer is used to show the validity of the algorithm.

The Flight Management System (FMS) has been identified by researchers, airline pilots, and airline instructors as hard to learn and difficult to use. Using the FMS to execute airline missiontasksrequiresthedevelopmentandmaintenanceofapilot’scognitiveskillstointeract with the FMS user-interface. This cognition is guided by visual cues (e.g. labels, prompts), user-interfaceconventions,andmemorizedactionsequences.Pilotactionspromptedbyvisual cues on the user-interface take less time to learn and reduce the likelihood of errors while performing infrequent tasks in revenue-service operations. The analysis described in this paper identified the presence of visual cues to completely guide all pilot actions for twenty five percent (25%) of 102 airline mission tasks performed using a modern FMS. Further, forty-five percent (45%) of the tasks were identified as occurring infrequently and were not completely supported by salient visual cues. The low percentage of tasks supported entirely by visual cues contributes to pilots perceptions about the difficulty in learning and using the FMS. Implications for training the FMS and the design of improved user-interfaces are discussed.

This paper describes a modular flight management system for unmanned multicopters, small unmanned fixed wing vehicles, vehicles used in Urban Air Mobility concepts, helicopters and other VTOL vehicles. With the expected growth in traffic of these types of vehicles especially in the urban environment it is necessary to generate reliable precalculated 4D trajectories for these vehicles. Furthermore, some of these vehicles need additional guidance to keep them on the precalculated path.The second central use case for this system is the fast trajectory calculation for fast and real time traffic simulations with a broad variety of vehicles, especially vehicles which are not covered by conventional flight management and trajectory generation systems.To solve these requirements, the system precalculates precise 4D trajectories for classic and experimental mission designs. These trajectories are tested for safety and continuity by a separate module and could then be executed on the corresponding vehicle (or a simulation) with the use of a guidance module.To calculate this huge variety of vehicles with different means of propulsion, the vehicle performance is kept in a separate module. This allows the system to not only work with different vehicle types, but also to switch between different vehicle configurations with considerable changes in the vehicle’s performance and behavior.Some of the targeted vehicles only exist in an earlier design stage or do not provide details performance information. Thus, the performance module is able to work with very simple performance modules based on early design conditions as well as detailed performance models based on exhaustive knowledge of the vehicle’s physical behavior.As the flight behaviors could change between the vehicles and their corresponding performance types, not all vehicles could use the same flight phases. Different parts of the trajectory are designed by different modules which specialize in the design of a specific flight phase. The performance module holds the information which flight phase could be applied on the vehicle and the corresponding boundaries. The system includes conventional flight phase modules for takeoff, cruise and landing and the transition between these phases as well as some specific flight phases, such as following waypoints relative to a moving target.The central trajectory management module then coordinates the different flight phases and ensures a continuous trajectory. This module also adds flight phases where required to guaranty a smooth transition between the different phases.Finally, this paper will show some example implementation of this system into traffic simulations and vehicle simulations.

A method for conflict detection and resolution based on the parameterization of the aircraft intents is presented. The method is also based on the use of predefined trajectory patterns, which are in fact flight intents; these patterns include standard airline procedures and air traffic control regulations. The conflict resolution problem is formulated as a parametric optimization problem subject to constraints; the optimality criterium is defined so that the deviation from the intended (preferred) trajectories in the lateral profile is minimized. The resolution trajectory patterns take into account changes of the nominal waypoints (vectoring) and changes of the aircraft speeds. The method is applied to the case of multiple conflicts among commercial transport aircraft in converging traffic in the terminal area; different scenarios are considered, which include locked aircraft, that is, aircraft whose trajectories are known and fixed. The conflict detection and resolution algorithm relies on a kinetic trajectory predictor (nonlinear point-mass model with variable mass), which is accurate, flexible, and transparent, and provides the high-fidelity prediction required in the analysis of the demanding terminal area traffic. The cost of the global conflict resolution process is assessed, in terms of extra distance traveled, extra flight time, and extra fuel consumed for each aircraft.

NASA researchers, working under the Aviation System Capacity Program and in conjunction with the FAA Free Flight Program Office, have developed a set of decision support tools to assist terminal area air traffic controllers with control of arrival and departure traffic. Two of these tools, the Final Approach Spacing Tool (FAST) and the Expedite Departure Path (EDP) tool, provide air traffic controllers with heading, speed and altitude advisories to assist in spacing aircraft. This paper describes the conflict prediction and resolution algorithm shared by aFAST and EDP to produce conflict-free aircraft trajectories with realistic conflict resolution maneuvers. The process is accomplished in three stages: prediction, classification and resolution. A conflict prediction scheme is documented which incorporates all applicable FAA separation requirements, including automatic detection of separation during transition from staggered to simultaneous parallel approach operations. A method of classifying predicted conflicts with a limited set of criteria is detailed. Finally, a knowledge-based conflict resolution process is presented which allows for resolution of predicted conflicts in a manner consistent with controller practice: including prioritization of resolution tactics and mixture of multiple degrees of freedom to achieve separation. The scheme has been employed in both closed-loop simulations to determine solution stability and controller-in-the-loop simulations to begin development of the resolution tactics knowledge base.

This paper presents a SOA and cloud computing based architecture for the distributed simulation of advanced flight management system (FMS). The architecture is designed to facilitate the fast simulation, validation and evaluation of different FMS system designs and functionalities with customized system configurations and widely varying aircraft equipage levels under various operation conditions. It is also intended to accommodate the potential evolutionary extensions of new avionics concepts and functionalities such as the future CNS/ATM and 4-D trajectory based technologies. To address the requirements of flexibility, scalability and reusability, the design of the simulation architecture takes advantage of the cloud computing and service oriented architecture (SOA) and the key enabling technologies are developed: simulation unit service encapsulation, simulation agent technology and simulation orchestration. Based on the proposed architecture associated technologies, the simulation components are encapsulated as services or accessed through agents, and the configuration of different FMS system frameworks and simulation tasks can be achieved through simulation orchestration. A prototype avionic simulation system that implements the SOA/cloud computing architecture is developed and illustrated with application cases. The applications demonstrate that the proposed architecture enables fast and scalable simulation of both existing and new FMS design and technologies.

A conflict detection and resolution (CD&R) concept for the terminal maneuvering area (TMA) was evaluated in a fast-time batch simulation study at the National Aeronautics and Space Administration (NASA) Langley Research Center. The CD&R concept is being designed to enhance surface situation awareness and provide cockpit alerts of potential conflicts during runway, taxi, and low altitude air-to-air operations. The purpose of the study was to evaluate the performance of aircraft-based CD&R algorithms in the TMA, as a function of surveillance accuracy. This paper gives an overview of the CD&R concept, simulation study, and results.

The final thesis focuses on the use of new technologies in the field of communication, navigation, and surveillance systems in general aviation. The thesis aims to supplement the study material for the subject Aeronautical Navigation 2, providing the reader with a comprehensive overview of modern systems used in aviation, their development, and functionality. The work focuses on the overview and analysis of current trends in digital communication systems such as Datalink, ACARS, CPDLC, and SATCOM, navigation technologies including Inertial Navigation and Reference Systems (INS, IRS), as well as the Flight Management System (FMS), and surveillance systems such as ADS-B and multilateration. The thesis also includes a historical context of the development of such aviation systems and an overview of the legislative frameworks at international, European, and national levels. As part of the design section of thesis, a proposal was written for the modernization of the aircraft fleet of the University of Žilina, with the aim of upgrading and providing training in accordance with current technological trends.

In the application of Internet of Things, UAV (Unmanned aerial vehicle) can be used in wireless image acquisition system, farmland information acquisition system, traffic monitoring system, infrared monitoring system and so on. With the extensive application of unmanned aerial vehicles in production and life, the need for effective supervision of unmanned aerial vehicles is increasingly urgent. According to the task requirements of UAV flight monitoring and control, an Internet of Things+UAV flight monitoring and management system is designed. The system realizes the functions of real-time acquisition of navigation parameters, on-line adjustment of flight control parameters, track planning and echo, data storage and analysis, etc., and provides favorable guarantee for over-the-horizon flight. Providing UAV with flight monitoring, aviation meteorology, planning management, aviation information, airspace management, system management and other services can ensure UAV to fly safely and orderly.

Stochastic optimal control for aircraft conflict resolution under wind uncertainty

Uninhabited Aerial Vehicles will require autonomous collisio n detection and avoidance capabilities in order to gain wide acceptance and usage in the National Airspace System. The collision detection and avoidance problem is primarily a motion estimation problem, relying on the accuracy of the sensing, processing, actuation and control algorithms onboard the vehicle. Computer vision is a growing field in robotics and autonomous vehicles, and has made vision a feasible technology for object detection in different platforms. In this work, we investigate the feasibil ity of using optic flow techniques in order to design an altitude hold controller for a fixed wing aircraft flying a nap -of -the -earth trajectory in the presence of variable terrain. Simulated results yield an error of approximately 1.5% in altitude variat ion for steady level flight (approximately 15 cm) for terrain disturbances of maximum amplitude 4 m. Experimental results obtained from flight data using the UIUC UAV platform are used to validate the controller, and sources of error along with potential improvements in equipment and procedures are cited. I. Introduction N essential challenge inherent to the integration of uninhabited aerial vehicles (UAVs) into the National Airspace System (NAS) is the inability to provide adequate safety assurances for th ese vehicles in a verifiable manner. The FAA requires that UAVs be capable of see -and -avoid functionality, unfortunately most solutions to the problem of autonomous surveillance, guidance and navigation are insufficiently scalable, reliable, verifiable or cost -effective. Implementation of safe and reliable object avoidance is crucial for the survival of autonomous vehicles intended to navigate in densely populated environments such as the NAS. In order to meet these stringent requirements, UAVs must be eq uipped with reactive sensing technologies that enable real -time conflict detection and object avoidance. Numerous techniques have been developed in the past few years to optimize the decision making process and solve the path planning problem in real -time , while accounting for aircraft dynamics, obstacle avoidance constraints and safe flight considerations. Regrettably, many of these techniques underestimate the difficulty of accurately sensing a dynamic and imperfect environment in an accurate and practic al manner. Making decisions based on distorted estimations of the surrounding environs is a pitfall that can destabilize even the most robust of path planning algorithms. Presently, state -of -the -art conflict detection and resolution systems employ a combi nation of radar, sonar and laser systems: while reliable, these systems are often prohibitive due to weight, size and equipment cost for certain UAV applications. Video recording devices are another alternative for environmental sensing, and have become standard equipment on many UAVs due to their exploratory nature. Although video images from this source are often intended for secondary mission purposes, such as target tracking and surveillance, they have been shown capable of providing valuable informati on for more important tasks, like collision avoidance. However, the nature of a fixed wing UAV platform brings rigorous safety requirements and constraints to the field of autonomous conflict detection and resolution: limited minimum flying speeds and res tricted maneuverability, thereby making the need for real -time sensing and decision -making paramount for safety purposes. In this paper we investigate the applicability of c omputer vision techniques that have been developed in order to estimate motion from two dimensional images. In the next section we provide a brief discussion of optical flow theory, and section 3 provides a direct implementation of the optical flow theory to an aircraft altitude controlle r. Section 4 provides the setup and simulation of several scenarios used to evaluate the performance of the controller designed in the previous section. Experimental video data taken from actual flight tests is used in order to asses the 1