Topic
Required navigation performance
About: Required navigation performance is a research topic. Over the lifetime, 343 publications have been published within this topic receiving 3477 citations. The topic is also known as: RNP.
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TL;DR: A number of Signals of Opportunity (SoOP) techniques are explored to improve the RNP when Unmanned Aerial Vehicles (UAV) are employed in urban canyons, providing a clear opportunity to provide considerable savings in both infrastructure as well as energy costs.
38 citations
20 Sep 2004
TL;DR: A system has been built to provide continuous real-time state estimates of the aircraft being tracked and a verification that the aircraft is following the ADS-B broadcast intent, and continuous Geometric Conformance and Intent Conformance metrics are defined to analyze ADS- B intent verification.
Abstract: *† ‡ § ** Automatic Dependent Surveillance – Broadcast (ADS-B) promises to provide significant operational enhancements to military and civilian applications. However, as currently designed, ADS-B will not necessarily provide guaranteed, uninterrupted state and intent data from ADS-B equipped aircraft. Data dropouts, erroneous inputs, and deception may degrade data integrity. To assure ADS-B data integrity, a system has been built to provide continuous real-time state estimates of the aircraft being tracked and a verification that the aircraft is following the ADS-B broadcast intent. This system uses a suite of Kalman filters to smooth out noise within measured ADS-B signals, identify and suppress erroneous data, coast between data dropouts, and provide the current best state estimates. Continuous Geometric Conformance and Intent Conformance metrics are defined to analyze ADS-B intent verification. Geometric Conformance analyzes the aircraft states to verify that the aircraft lies within the horizontal and vertical Required Navigation Performance (RNP) limits. Intent Conformance compares the aircraft motion and the broadcast intent in horizontal, vertical, and speed dimensions. Examples demonstrate data integrity checks with simulated ADS-B data signals.
37 citations
Journal Article•
TL;DR: The main objectives of this paper are to uncover the constraints and limitations by an in-depth literature review and to recommend ideas to address them, including some ideas for monitoring the integrity of map matching algorithms.
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.
35 citations
TL;DR: A low cost navigation system based on Vision Based Navigation and other avionics sensors is presented, which is designed for small size Unmanned Aerial Vehicle (UAV) applications and shows that the integrated system can reach position, velocity and attitude accuracies compatible with CAT-II precision approach requirements.
Abstract: A low cost navigation system based on Vision Based Navigation (VBN) and other avionics sensors is presented, which is designed for small size Unmanned Aerial Vehicle (UAV) applications. The main objective of our research is to design a compact, lightweight and relatively inexpensive system capable of providing the required navigation performance in all phases of flight of a small UAV, with a special focus on precision approach and landing, where Vision Based Navigation (VBN) techniques can be fully exploited in a multisensory integrated architecture. Various existing techniques for VBN are compared and the Appearance-based Navigation (ABN) approach is selected for implementation. Feature extraction and optical flow techniques are employed to estimate flight parameters such as roll angle, pitch angle, deviation from the runway and body rates. Additionally, we address the possible synergies between VBN, Global Navigation Satellite System (GNSS) and MEMS-IMU (Micro-Electromechanical System Inertial Measurement Unit) sensors and also the use of Aircraft Dynamics Models (ADMs) to provide additional information suitable to compensate for the shortcomings of VBN and MEMS-IMU sensors in high-dynamics attitude determination tasks. An Extended Kalman Filter (EKF) is developed to fuse the information provided by the different sensors and to provide estimates of position, velocity and attitude of the UAV platform in real-time. Two different integrated navigation system architectures are implemented. The first uses VBN at 20 Hz and GPS at 1 Hz to augment the MEMS-IMU running at 100 Hz. The second mode also includes the ADM (computations performed at 100 Hz) to provide augmentation of the attitude channel. Simulation of these two modes is performed in a significant portion of the AEROSONDE UAV operational flight envelope and performing a variety of representative manoeuvres (i.e., straight climb, level turning, turning descent and climb, straight descent, etc.). Simulation of the first integrated navigation system architecture (VBN/IMU/GPS) shows that the integrated system can reach position, velocity and attitude accuracies compatible with CAT-II precision approach requirements. Simulation of the second system architecture (VBN/IMU/GPS/ADM) also shows promising results since the achieved attitude accuracy is higher using the ADM/VBS/IMU than using VBS/IMU only. However, due to rapid divergence of the ADM virtual sensor, there is a need for frequent re-initialisation of the ADM data module, which is strongly dependent on the UAV flight dynamics and the specific manoeuvring transitions performed.
33 citations
25 Apr 2006
TL;DR: Results clearly show that HIGH can support lower RNP operations such as RNP 0.1 as well as future lower R NP levels, and are contrasted with stand-alone GPS systems.
Abstract: Honeywell has developed an algorithm that tightly integrates GPS and IRS into a hybrid navigation solution adequate to achieve 100% worldwide availability of RNP 0.1 without the use of differential corrections. This algorithm, referred to as Honeywell Inertial GPS Hybrid (HIGH), improves all four of the navigation characteristics critical for RNP operations - accuracy, integrity, continuity and availability. With its increased level of availability, HIGH can support RNP operations that are lower than can be achieved with stand-alone GPS. RNP operations require the navigation system provide an integrity bound called Horizontal Integrity Limit (HIL). An RNP operation can proceed as long as the HIL remains below the threshold required for that operational level. On average, stand-alone HILs are at least 50% worse than HIGH HILs under good satellite geometries, and become significantly degraded or unavailable when in RAIM holes or during GPS outages. HIGH enhances system continuity by coasting on the inertial when no satellite measurements are available. Honeywell has applied the HIGH technology on both military and commercial aircraft platforms. Operational benefits of HIGH are examined and contrasted with stand-alone GPS based solutions. HIGH is based on Honeywell's solution separation method to provide the integrity level and the Fault Detection and Exclusion (FDE) capability. With this method, a bank of Kalman filters is used to provide multiple hybrid solutions, each excluding different combinations of zero, one or two satellites. The algorithm detects and isolates a satellite failure by comparing the various solutions. Since one of the solutions will not contain the effects of the satellite error, an uncorrupted solution is always available. Appendix R of RTCA/DO-229C provides the requirements and test procedures for tightly integrated GPS/Inertial systems. Honeywell's HIGH implementations have demonstrated compliance to Appendix R. Compliance to Appendix R is critical to ensure a consistent basis for certification for these types of systems. The paper provides results from flight tests and simulations implementing the HIGH technology. These results support the claimed enhanced performance for integrity, continuity and availability and are contrasted with stand-alone GPS systems. The results clearly show that HIGH can support lower RNP operations such as RNP 0.1 as well as future lower RNP levels. Plans for enhancing the performance in future applications are also examined. I. INTRODUCTION The required navigation performance (RNP) concept allows aircraft to operate in a defined airspace based on the
32 citations