Showing papers on "Required navigation performance published in 2017"

An Analysis of Map Matching Algorithm for Recent Intelligent Transport System

Abstract: Map matching is a technique combining electronic map with locating information to obtain the real position of vehicles in a road network. Map matching algorithms can be divided in real-time and offline algorithms. Real-time algorithms associate the position during the recording process to the road network. Offline algorithms are used after the data is recorded and are then matched to the road network. Real-time applications can only calculate based upon the points prior to a given time (as opposed to those of a whole journey), but are intended to be used in 'live' environments. This brings a compromise of performance over accuracy. Offline applications can consider all points and so can tolerate slower performance in favour of accuracy. The MM algorithms integrate positioning data with spatial road network data to identify the correct link on which a vehicle is travelling and to determine the location of a vehicle on a link. A map-matching algorithm could be used as a key component to improve the performance of systems that support the navigation function of intelligent transport systems. A number of map-matching algorithms have been developed by around the world using different techniques such as topological analysis of spatial road network data, probabilistic theory, fuzzy logic, and belief theory. The performances of these algorithms have improved over the years due to the application of advanced techniques in the map matching processes and improvements in the quality of both positioning and spatial road network data. However, these algorithms are not always capable of supporting intelligent transport system applications with high required navigation performance, especially in difficult and complex environments such as dense urban areas. The main objectives of this paper are thus to uncover the constraints and limitations by an in-depth literature review and to recommend ideas to address them. This paper also presents some ideas for monitoring the integrity of map matching algorithms. The map-matching algorithms considered in this paper are generic and do not assume knowledge of ‘future’ information (i.e. based on either cost or time). Clearly, such data would result in relatively simple map-matching algorithms.

A Novel Vehicle-Based GNSS Integrity Augmentation System for Autonomous Airport Surface Operations

Abstract: Autonomous vehicles equipped with integrity augmentation systems offer the potential to increase safety, efficiency and sustainability of airport ground operations. The model predictive behavior of these systems supports a timely detection of any deviations from the Required Navigation Performance (RNP), producing useful alerts for onboard mission management. Firstly, the system architecture of a Navigation and Guidance System (NGS) for autonomous airport surface vehicle operations based on Global Navigation Satellite System (GNSS) measurements is described. Subsequently, an integrity augmentation module is implemented in the NGS by modeling the key GNSS signal degradation phenomena including masking, multipath and signal attenuation. The GNSS integrity augmentation system is capable of monitoring the RNP and alerting the remote operator of the airport surface vehicle. The uniqueness of the presented system is that both caution and warning flags are produced based on prediction-avoidance and reaction-correction capabilities respectively. Additionally, the system is capable of issuing suitable steering commands to the onboard mission management system/remote ground base station operator in the event of GNSS signal degradations or losses. Multipath is modelled in detail using a ray tracing algorithm and the vehicle position error is computed as a function of relative geometry between the satellites, receiver antenna and reflectors in realistic airport operation scenarios. Additionally, the surface vehicle dynamics and reflective surfaces of buildings are modelled in order to simulate a vehicle trajectory through a typical airport airside/aprons environment. Simulation case studies are performed to validate the mathematical models developed for the integrity augmentation system and the results corroborate the suitability of the proposed system to generate useful and timely integrity flags when GNSS is used as the primary means of navigation.

Feasibility analysis of low-cost GNSS receivers for achieving required positioning performance in CAV applications

Abstract: For Connected and Autonomous Vehicle (CAV) applications, the location solution is desired to provide better than 0.1m real-time positioning accuracy. This level of accuracy can only be achieved by using geodetic GNSS receivers under an open sky observation condition, and each unit costs around £20,000. This kind of geodetic GNSS receiver is not a good option for mass market use in terms of price and ubiquity aspects. Therefore, using low-cost receiver to achieve real-time, high accuracy and ubiquitous positioning performance could be a future trend. This paper will first establish a framework of assessing low-cost receivers based on required navigation performance (RNP) concept in aviation and required accuracy categories in ITS. Then adynamic test that was conducted to simulate the future CAV driving environment will be introduced. Under the guidance of the former established framework, the collected data was post-processed to explore the real positioning performance of both two grades receivers. By comparing real-time/post-processed results and high-end/low-cost receivers, the limitations and technical gaps between two types of receivers, as well as current positioning solution and required positioning performance will be identified.

Integrity monitoring in GNSS/INS systems by optical augmentation

Abstract: Reliable aircraft guidance is one of the main contributors to the high level of safety that is achieved today on modern aircraft. Especially during the landing phase, where aircraft are close to other surrounding traffic and ground obstacles, any undetected deviation from the desired flight path may lead to catastrophic consequences. Automatic landing systems today are based on different ground-based guidance techniques, for example the Instrument Landing System (ILS). They perform well but are expensive in terms of installation and maintenance costs and therefore are only available on bigger airports. In contrast smaller General Aviation (GA) aircraft and regional airports often are not equipped with the above named landing systems. Therefore, this paper presents an alternate low cost aircraft autonomous landing system for GA aircraft, which does not require any type of ground-based navigation equipment. The system consists of a classical GNSS/INS system that is augmented by a new optical positioning system for integrity monitoring. The monitor ensures that any deviation caused by either the navigation system or the guidance system will alert the pilot and trigger an automatic go-around maneuver. This paper outlines the developed system architecture and presents the basic monitoring algorithms. The system was designed in compliance with the Required Navigation Performance (RNP) concept introduced and published by ICAO. The system is still under development and was tested during real flight trials onboard a twin-engine Dornier 128 aircraft during various approaches on Braunschweig airport, see figure 1. This paper presents a profound analysis of the achieved system performance during normal operation and discusses the error budgets that result from the positioning system on the one hand and the flight control deviation on the other. Finally, simulated sensor errors were applied to the recorded flight data in order to demonstrate the fault detection capability within the necessary time to alert. The following analysis presents the performance that can already be achieved by the system today and identify potential gaps with respect to the required system performance.

Optimization-Based Design of Departure and Arrival Routes in Terminal Maneuvering Area

Abstract: The efficient design of departure and arrival routes in the airspace surrounding airports, called the terminal maneuvering area, is crucial for increasing the capacity of such areas, thus alleviati...

Trajectory Specification for Terminal Air Traffic: Pairwise Conflict Detection and Resolution

Abstract: Trajectory Specification is the explicit bounding and control of aircraft trajectories such that the position at any point in time is constrained to a precisely defined volume of space. The bounding space is defined by cross-track, along-track, and vertical tolerances relative to a reference trajectory that specifies position as a function of time. The tolerances are dynamic and will be based on the aircraft navigation capabilities and the current traffic situation. Assuming conformance, Trajectory Specification can guarantee safe separation for an arbitrary period of time even in the event of an air traffic control (ATC) system or datalink failure; hence it can help to achieve the high level of safety and reliability needed for ATC automation. It can also reduce the reliance on tactical backup systems during normal operation. This paper applies it to the terminal area around a major airport and presents algorithms and software for detecting and resolving conflicts. A representative set of pairwise conflicts was generated, and a fast-time simulation was run on them. All conflicts were successfully resolved in real time, demonstrating the computational feasibility of the concept.

Operational Receiver Autonomous Integrity Monitoring Prediction System for Air Traffic Management System

Abstract: The Global Positioning System (GPS) is the key enabling technology for new air traffic management (ATM) systems. However, for civil aviation safety-of-life applications, the sensors of an ATM system using GPS must meet the required navigation performance, especially integrity. According to a new ATM system requirement, the receiver autonomous integrity monitoring (RAIM) prediction system (RPS) is an essential element for predicting GPS service quality for a 72 h period. Many web-based RPSs have been developed and are operated by civil aviation organizations around the world. However, none can autonomously provide the GPS RAIM availability information to the new ATM system. Thus, this study develops an RPS that can be integrated with the new ATM system. Airport operators can obtain the forecast results directly from the ATM system for a specific flight-information region. The system integration is validated using three years of actual operation results of the new ATM system. An evaluation of its support fo...

Placing LDACS-based ranging sources for robust RNP 1.0 accuracy en-route

Abstract: Global Navigation Satellite Systems (GNSS) are becoming the primary means of navigation for civil aviation. Nevertheless, concerns about GNSS outages remain, driving the need for Alternative Positioning, Navigation and Timing (APNT) systems to provide availability and continuity for performance-based navigation services. Although the existing Distance Measuring Equipment (DME) infrastructure is able to provide Required Navigation Performance (RNP) 1.0 accuracy, it is not robust for individual station outages. Additionally, we show that in the European airspace DME is reaching the capacity limit. To address these two problems, we propose a methodology based on modular APNT. In the presented approach, the complementary ranging sources are optimally placed to obtain robustness. It is assumed that the L-Band Digital Aeronautical Communications System (LDACS) can provide this capability. As shown in the results, the modular APNT system is able to provide robust RNP 1.0 coverage for Germany using 17 new LDACS ground stations to complement the network of 73 existing DME installations in Germany.

GNSS/Electronic Compass/Road Segment Information Fusion for Vehicle-to-Vehicle Collision Avoidance Application

Abstract: The increasing number of vehicles in modern cities brings the problem of increasing crashes. One of the applications or services of Intelligent Transportation Systems (ITS) conceived to improve safety and reduce congestion is collision avoidance. This safety critical application requires sub-meter level vehicle state estimation accuracy with very high integrity, continuity and availability, to detect an impending collision and issue a warning or intervene in the case that the warning is not heeded. Because of the challenging city environment, to date there is no approved method capable of delivering this high level of performance in vehicle state estimation. In particular, the current Global Navigation Satellite System (GNSS) based collision avoidance systems have the major limitation that the real-time accuracy of dynamic state estimation deteriorates during abrupt acceleration and deceleration situations, compromising the integrity of collision avoidance. Therefore, to provide the Required Navigation Performance (RNP) for collision avoidance, this paper proposes a novel Particle Filter (PF) based model for the integration or fusion of real-time kinematic (RTK) GNSS position solutions with electronic compass and road segment data used in conjunction with an Autoregressive (AR) motion model. The real-time vehicle state estimates are used together with distance based collision avoidance algorithms to predict potential collisions. The algorithms are tested by simulation and in the field representing a low density urban environment. The results show that the proposed algorithm meets the horizontal positioning accuracy requirement for collision avoidance and is superior to positioning accuracy of GNSS only, traditional Constant Velocity (CV) and Constant Acceleration (CA) based motion models, with a significant improvement in the prediction accuracy of potential collision.

Integrated GNSS/DR/road segment information system for variable road user charging

Abstract: Road User Charging (RUC) is designed to reduce congestion and collect revenue for the maintenance of transportation infrastructure. In order to determine the charges, it is important that appropriate Road User Charging Indicators (RUCI) are defined. This paper focusses on Variable Road User Charging (VRUC) as the more dynamic and flexible compared to Fixed Road User Charging (FRUC), and thus is a better reflection of the utility of the road space. The main issues associated with VRUC are the definition of appropriate charging indicators and their measurement. This paper addresses the former by proposing a number of new charging indicators, considering the equalization of the charges and marginal social cost imposed on others. The measurement of the indicators is addressed by a novel data fusion algorithm for the determination of the vehicle state based on the integration of Global Navigation Satellite Systems (GNSS) with Dead Reckoning (DR) and road segment information. Statistical analyses are presented in terms of the Required Navigation Performance (RNP) parameters of accuracy, integrity, continuity and availability, based on simulation and field tests. It is shown that the proposed fusion model is superior to positioning with GPS only, and GPS plus GLONASS, in terms of all the RNP parameters with a significant improvement in availability.

Fault-tolerant airport vehicle integrated navigation system

Abstract: A fault-tolerant airport vehicle integrated navigation system as a structural part of Advanced Surface Movement Guidance and Control System (A-SMGCS) is presented in the report. The structure of airport vehicle navigation system algorithms, algorithms of complex information processing (CIP), with an increased resistance to internal and external disturbances of unknown origin and realizing functions of detection, control and exclusion of satellite signals from navigation solution, which contain errors of different origin and type are given. Based on this approach integrity monitoring algorithm of navigation system is built. The basis of system is strapdown inertial navigation system (SINS), corrected by global navigation system (GNSS) receiver and odometer dead reckoning system (ORS). Two approaches to improve the reliability of system navigation definitions are offered, one of which is based on the navigation data autonomous integrity monitoring coming from the GNSS receiver and the second — on the use of data from ORS and nonholonomic properties in case of vehicle moving without a slip. Simulation results of airport vehicle navigation system error estimation process and detection of navigation satellites failures are given, confirming developed algorithms operability and efficiency.

Safety assessment of RNP AR approach procedures

Abstract: The required navigation performance authorisation required (RNP AR) approach, which is one of the performance-based navigation procedures, enables safer and efficient flight operations in busy and challenging mountainous areas. The RNP system increases situational awareness of pilots because of including monitoring and alerting service on board and ensuring lateral track accuracy of up to ± 0.1 NM. In this study, RNP AR approach (RNP AR APCH) procedures which will be a solution to prevent controlled flight into terrain (CFIT) accidents are defined. CFIT accidents mostly occur in the approach and landing phase of flights because of the lack of precision approaches. Moreover, flight operational safety assessment (FOSA) methodology published for only RNP AR APCH procedures is assessed. The FOSA is a significant part of the operational authorisation for RNP AR APCH procedures and also is applied to evaluate particular cases and could be useful method for mitigating the risk of CFIT.

Geometric approach for RNP transition to xLS procedure design

Abstract: The required navigation performance (RNP) transition to a xLS (ILS/GLS) is expected to be a near future flight procedure to reduce flight time and fuel burn, and enable precision approach. However, for the development of this new procedure design criteria, there are some problems regarding the transition from RNP segment to the xLS precision approach segment. This paper reveals the requirements to allow an aircraft to smoothly fly on the intended path including the transition. Based on the obtained requirements, a full-flight simulator experiment was conducted, and the requirements were proven to be appropriate. Finally, based on these requirements, the RNP transition to xLS flight procedures design criteria was developed to enable a procedure designer to design a flyable RNP transition to xLS procedure.

Automatic speed profiling and automatic landings during advanced RNP to xLS flight tests

Abstract: We report on the performance of our Airbus 320 during novel advanced required navigation performance (RNP) procedures which contain a fixed radius turn that delivers the aircraft onto a short ILS precision final above aerodrome level. The approaches were flown automatically with guidance and autothrust as computed by the flight management system. Main areas of interest of the flight trials were the performance of the autoland capability, vertical path following during the RNP part of the procedure as well as maintaining an optimized speed profile during the continuous descent approaches Within the PBN concept exists the possibility to incorporate turns with a precise ground track into departure, en-route, arrival and approach procedures called fixed radius transitions or radius-to-fix. They offer the advantage of repeatable ground tracks during the turn and thus more freedom for the procedure designer when route planning in dense traffic, high terrain or obstacle rich environments. Additionally, ARINC 424 allows to specify altitude constraints at waypoints and vertical path angles for each RNP segment terminating at such a waypoint. Whilst offering these benefits such advanced RNP approach operations are still non-precision procedures and automatic landings cannot be performed after their successful completion. Hence, to enable automatic landings and to extract maximum benefits from RNP operations, they must transition into a precision final approach segment provided by any precision landing system (ILS, GLS, MLS) so that the guidance loops for flare and land modes of the auto flight guidance system can activate. This is often called RNP to xLS (or RNP2xLS). Moreover, the vertical path angle feature is currently largely unused and unexplored, except for the final approach segment of an RNP approach. These new options, when properly exercised, would allow any aircraft to benefit from better fuel efficiency during a continuous descent approach and a potentially reduced obstacle clearance due to the fixed vertical RNP profile and RF tracks. Ground tracks are repeatable and could be used for better noise abatement — besides their main purpose, obstruction clearance along the aircraft's path. In this study we investigated the use of the described ARINC424 coding options onto (a) the performance of the speed profile for arrival time optimization (b) the vertical path during the RNP part of the procedure and (c) the performance of the autoland capability after a curved transition onto an ILS. For the trials, we designed five instrument approaches to runway 26 at Braunschweig-Wolfsburg airport, which is equipped with an Instrument Landing System. A RF curve terminates at the ILS intercept point at heights 550ft, 750ft, 1000ft, 1500ft and 2000ft above aerodrome level and each approach had four different initial approach fixes which corresponded to a track angle change of 30,60,90 and 180 degrees during the constant radius turn-to-final. For each initial approach path coded as advanced RNP segments, we programmed different combinations of vertical path angle and height constraints at waypoints. Moreover, as the thrust computer automatically reduces speed to a value suitable for initial approach, we varied the distance of the initial approach fix of one of the approaches from ranging between 3 to 7NM from the FAF in order to allow the aircraft to decelerate as late as possible. For the trials, we used DLR's own Advanced Technology Research Aircraft (ATRA), an Airbus A320 MSN659 with flight test instrumentation and a Thales FMS2. The approaches were entirely flown using the auto flight guidance in managed mode and with auto-thrust activated. The approach mode was armed either at the FAF or before the initial approach fix. We show supporting evidence that RNP2ILS approaches can be safely flown all the way to an automatic landing using the flight management guidance computer and the auto flight control system. In order to fly the desired path with vertical path angle during the RNP initial and intermediate approach, a separate mode (such as LNAV/VNAV) different from the singular approach mode would need to be implemented in the aircraft. Additionally, airlines and other operators currently apply stabilization criteria following which the aircraft must be established on a straight final with the correct sink rate at 1000ft above aerodrome level in order to continue the approach. For landings in low visibility conditions, more stringent criteria are often applied. An operational implementation of RNP2ILS approaches with a curved final intercept would require a rephrasing of the criteria to include a concept such as RNP established.

Midair collision risk when executing an incorrect approach during established on required navigation performance operations

Abstract: Providing improved efficiency in the terminal environment around high-capacity airports, Established on RNP leverages Required Navigation Performance technology to safely allow reduced aircraft-to-aircraft separation during curved simultaneous approaches. As one element in a comprehensive safety analysis, this paper describes the methodology and results used to estimate the mid-air collision risk when at least one aircraft leaves the intended approach path by inadvertently selecting an unintended flight procedure. The analysis considers three possible cases where an aircraft could be put at risk of collision during such an event: one where the trailing aircraft flying to the intended runway may be put at risk; a second where an aircraft flying to the incorrectly selected runway is put at risk; and, a third case, which only occurs when more than three parallel runways are available, where an aircraft flying to a runway between the intended runway and the incorrectly selected runway is put at risk of collision. The analysis concludes that all three cases could pose significant risk if not appropriately mitigated with controller monitoring and procedure design, but the third case is the most severe.

Integration of an ARAIM algorithm in the development of an instrument approach procedure and for pre-flight operational briefing

Abstract: Advanced Receiver Autonomous Integrity Monitoring (ARAIM) offers the opportunity to enable Global Navigation Satellite System (GNSS) receivers to serve as a primary means of navigation, worldwide, for precision approach down to Localizer Performance with Vertical guidance (LPV-200) operation. Previous produced works analysed the performance of this new technique, clearly showing the potential of ARAIM architectures to provide the Required Navigation Performance (RNP) for LPV 200. However, almost all of the studies were performed with respect to fixed points on a grid on the Earth’s surface, with full view of the sky, evaluating ARAIM performance from a geometrical point of view and using nominal performance in simulated scenarios lasting several days. In our previous work we presented the ARAIM performance in simulated operational configurations. Attitude changes from manoeuvers, obscuration by the aircraft body and shadowing from the surrounding environment could all affect the incoming signal from the GNSS constellations, leading to configurations that could adversely affect the real performance. In this paper, we continue the previous work. The new proposed algorithm integrates ARAIM performance prediction capability, considering the attitude and terrain shadowing effects, in two different scenarios: In the design of instrument approach procedures. The algorithm could be used to improve the procedure of the development of new instrument approaches, reducing time, effort and costs. In the aircraft Flight Management Systems. The algorithm could support the pilots in the pre-flight briefing, highlighting possible integrity outage in advance and allowing them to select a different approach or making them aware of the need to utilise additional positioning systems. Increased awareness and better pre-flight planning could ultimately improve the safety of flights and contribute to the safe introduction of GNSS as a viable positioning method for instrument approach.

Operational Feasibility of Segmented Independent Parallel Approaches

Abstract: Noise, especially in the vicinity of airports, is one of the most important factors of modern air transport systems, especially at major hub airports. New approach designs like curved Required Navigation Performance (RNP) procedures to independent parallel runway systems can decrease the noise footprint in sensitive ground areas without reducing airport capacity. So far, only straight-in ILS (or MLS) approaches are allowed for independent parallel approach operations. To introduce RNP curved/segmented approaches as a further option for independent approaches to a parallel runway system, a safety concept has been developed by DLR in recent years based on the ICAO SaRPS for independent parallel approaches (ICAO Doc 9643). Following this concept, curved RNP approach operations should be possible at Frankfurt/Main airport enabling noise abatement even in high density traffic situations. This paper considers the operational aspects of independent segmented parallel approach procedures at major airport-hubs with parallel runway systems like Frankfurt Airport. It reports about a new route design enabling the management of mixed aircraft equipage. The focus is on the operational feasibility of the new TMA design. This has been assessed by a real-time simulation with controllers of the German Air Navigation Service (DFS). The results of these simulations are presented in this paper

Quantification of midair collision risk for established on required navigation performance operations

Abstract: Established on Required Navigation Performance (EoR) (RNP) is an operational concept which leverages performance-based navigation (PBN) to eliminate the separation requirement of 1000 feet vertically or 3 nautical miles horizontally. EoR promises many benefits to the National Airspace System (NAS) such as increased navigational performance, reduced pilot and controller work load, and lower track miles flown. Prior work presented the results from human-in-the-loop experimentation designed to assess these operations and the development of collision risk models that leverage these experimental results. This paper focuses on the application of the models recently derived and interpretation of results obtained. The results indicate mid-air collision risk is between 10−9 and 10−10 per operation for simultaneous independent EoR operations to dual parallel runways separated by 3600 feet or greater and to triple parallel runways separated by 3900 feet or greater regardless of whether the turns were designed with TF or RF legs.