On the Availability of Fault Detection and Exclusion in GNSS Receiver Autonomous Integrity Monitoring

2009 ◽  
Vol 62 (2) ◽  
pp. 251-261 ◽  
Author(s):  
Jinling Wang ◽  
Pieter B. Ober
Keyword(s):  
Real Time ◽  
Satellite System ◽  
Integrity Monitoring ◽  
Actual Performance ◽  
The Real ◽  
Gnss Receiver ◽  
Expected Performance ◽  
Receiver Autonomous Integrity Monitoring ◽  
Integrity Risk ◽  
Global Navigation Satellite

Global Navigation Satellite System (GNSS) Receiver Autonomous Integrity Monitoring (RAIM) is essential for safety-of-life and liability critical applications. This paper discusses two fundamentally different ways to assess the integrity risk of an operation with RAIM, based on a different amount of information available: the expected (or average) performance that is computed using the GNSS models only and the real-time (or actual) performance, which also uses information on the internal status of a GNSS receiver. It is shown both theoretically and by simulation that the real-time integrity risk significantly exceeds the expected risk after the detection and exclusion of a failing satellite. Therefore, while most published RAIM algorithms base their performance assessment on the expected performance only, this is only correct when the requirements allow the risk evaluation to be averaged over multiple operations. However, when the GNSS integrity requirement is to be applied on a ‘per operation’ basis, real-time integrity measures are more appropriate.

scholarly journals Analyses of the sensitivity of multi-constellation advanced receiver autonomous integrity monitoring vertical protection level availability to error parameters and a failure model over China

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401877619 ◽  
Author(s):  
Xueen Zheng ◽  
Ye Liu ◽  
Guochao Fan ◽  
Jing Zhao ◽  
Chengdong Xu
Keyword(s):  
Satellite System ◽  
Protection Level ◽  
Integrity Monitoring ◽  
System Service ◽  
Service Stations ◽  
Receiver Autonomous Integrity Monitoring ◽  
Global Navigation Satellite ◽  
Range Error ◽  
Monitoring Algorithm ◽  
Advanced Receiver

The availability of advanced receiver autonomous integrity monitoring for vertical guidance down to altitudes of 200 ft (LPV-200) is discussed using real satellite orbit/ephemeris data collected at eight international global navigation satellite system service stations across China. Analyses were conducted for the availability of multi-constellation advanced receiver autonomous integrity monitoring and multi-fault advanced receiver autonomous integrity monitoring, and the sensitivity of availability in response to changes in error model parameters (i.e. user range accuracy, user range error, Bias-Nom and Bias-Max) was used to compute the vertical protection level. The results demonstrated that advanced receiver autonomous integrity monitoring availability based on multiple constellations met the requirements of LPV-200 despite multiple-fault detections that reduced the availability of the advanced receiver autonomous integrity monitoring algorithm; the advanced receiver autonomous integrity monitoring availability thresholds of the user range error and Bias-Nom used for accuracy were more relevant to geographic information than the user range accuracy and Bias-Max used for integrity at the eight international global navigation satellite system service stations. Finally, the possibility of using the advanced receiver autonomous integrity monitoring algorithm for a Category III navigation standard is discussed using two sets of predicted errors, revealing that the algorithm could be used in 79% of China.

Failure Modes and Models for Integrated GPS/INS Systems

2007 ◽  
Vol 60 (2) ◽  
pp. 327-348 ◽  
Author(s):  
Umar Iqbal Bhatti ◽  
Washington Yotto Ochieng
Keyword(s):  
Failure Modes ◽  
Cost Effective ◽  
Satellite System ◽  
Integrated System ◽  
Data Consistency ◽  
Coupling Mechanism ◽  
Integrity Monitoring ◽  
Potential Failure ◽  
Receiver Autonomous Integrity Monitoring ◽  
Global Navigation Satellite

GPS is the most widely used global navigation satellite system. By design, there is no provision for real time integrity information within the Standard Positioning Service (SPS). However, in safety critical sectors like aviation, stringent integrity performance requirements must be met. This can be achieved externally or at the receiver level through receiver autonomous integrity monitoring (RAIM). The latter is a cost effective method that relies on data consistency, and therefore requires redundant measurements. An external aid to provide this redundancy can be in the form of an Inertial Navigation System (INS). This should enable continued performance even during RAIM holes (when no redundant satellite measurements are available). However, due to the inclusion of an additional system and the coupling mechanism, integrity issues become more challenging. To develop an effective integrity monitoring capability, a good understanding of the potential failure modes of the integrated system is vital. In this paper potential failure modes of integrated GPS/INS systems are identified. This is followed by the specification of corresponding models that would be required to investigate the capability of existing integrity algorithms and to develop enhancements or new algorithms.

Integrity monitoring for Kalman filter-based localization

2020 ◽  
Vol 39 (13) ◽  
pp. 1503-1524
Author(s):  
Guillermo Duenas Arana ◽  
Osama Abdul Hafez ◽  
Mathieu Joerger ◽  
Matthew Spenko
Keyword(s):  
Kalman Filter ◽  
Time Window ◽  
Satellite System ◽  
Navigation Satellite ◽  
Robot Localization ◽  
Sensor Faults ◽  
Prior Work ◽  
Integrity Monitoring ◽  
Integrity Risk ◽  
Global Navigation Satellite

The problem of quantifying robot localization safety in the presence of undetected sensor faults is critical when preparing for future applications where robots may interact with humans in life-critical situations; however, the topic is only sparsely addressed in the robotics literature. In response, this work leverages prior work in aviation integrity monitoring to tackle the more challenging case of evaluating localization safety in Global Navigation Satellite System (GNSS)-denied environments. Localization integrity risk is the probability that a robot’s pose estimate lies outside pre-defined acceptable limits while no alarm is triggered. In this article, the integrity risk (i.e., localization safety) is rigorously upper bounded by accounting for both nominal sensor noise and other non-nominal sensor faults. An extended Kalman filter is employed to estimate the robot state, and a sequence of innovations is used for fault detection. The novelty of the work includes (1) the use of a time window to limit the number of monitored fault hypotheses while still guaranteeing safety with respect to previously occurring faults and (2) a new method to account for faults in the data association process.

A distribution model of the GNSS code noise and multipath error considering both elevation angle and orbit type

2018 ◽  
Vol 233 (5) ◽  
pp. 1900-1915 ◽  
Author(s):  
Guochao Fan ◽  
Chengdong Xu ◽  
Jing Zhao ◽  
Xueen Zheng
Keyword(s):  
Prior Information ◽  
Elevation Angle ◽  
Satellite System ◽  
Distribution Model ◽  
Orbit Type ◽  
Integrity Monitoring ◽  
Multipath Error ◽  
Receiver Autonomous Integrity Monitoring ◽  
Orbit Types ◽  
Global Navigation Satellite

Commonly, the code noise and multipath error is considered to fully obey the Gaussian distribution. While in the cases with different elevation angles and orbit types, the assumption may be inappropriate. Based on an empirical study, by considering both the elevation angle and the orbit type, a new code noise and multipath distribution model is proposed to describe a more accurate code noise and multipath distribution in this paper. Actual code noise and multipath data from 10 observation stations during two months are researched, and the parameters and elevation angle range of code noise and multipath distribution model are determined. The code noise and multipath distribution model is verified to be more accurate than the model presented in the Global Navigation Satellite System Evolutionary Architecture Study report, according to the analysis on the code noise and multipath overbounding, position error overbounding, and the availability of receiver autonomous integrity monitoring. This model provides more accurate prior information for receiver autonomous integrity monitoring, especially its availability.

The Effect of Terrain Mask on RAIM Availability

2009 ◽  
Vol 63 (1) ◽  
pp. 105-117 ◽  
Author(s):  
Tomislav Radišić ◽  
Doris Novak ◽  
Tino Bucak
Keyword(s):  
Global Navigation Satellite System ◽  
Satellite System ◽  
Navigation Satellite ◽  
Integrity Monitoring ◽  
Specific Location ◽  
Gps Satellites ◽  
Satellite Geometry ◽  
Minimum Number ◽  
Receiver Autonomous Integrity Monitoring ◽  
Global Navigation Satellite

Receiver Autonomous Integrity Monitoring (RAIM) is a method, used by an aircraft's receiver, for detecting and isolating faulty satellites of the Global Navigation Satellite System (GNSS). In order for a receiver to be able to detect and isolate a faulty satellite using a RAIM algorithm, a couple of conditions must be met: a minimum number of satellites, and an adequate satellite geometry. Due to the highly predictable orbits of the GPS satellites, a RAIM availability prediction can be done easily. A number of RAIM methods exist; however, none of them takes into account the precise terrain masking of the satellites for the specific location. They consider a uniform fixed mask angle over the whole horizon. This paper will introduce the variable mask RAIM algorithm in order to show to what extent the terrain can affect the RAIM availability and how much it differs from the conventional algorithms.

scholarly journals Real-time integrity monitoring for a wide area precise positioning system

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Yuechen Wang ◽  
Jun Shen
Keyword(s):  
Real Time ◽  
High Precision ◽  
Satellite Orbit ◽  
Satellite System ◽  
Wide Area ◽  
Positioning System ◽  
Dual Frequency ◽  
Integrity Monitoring ◽  
Precise Positioning ◽  
Global Navigation Satellite

Abstract The wide area precise positioning system (WAPPS) is a high-precision positioning system based on a global navigation satellite system. Using a GEO satellite or a communication network, it provides users, in its service area, with real-time satellite orbit, clock, and other corrections. Users can achieve centimeter-level static positioning or decimeter-level kinematic positioning by precise point positioning. With the demands for applications of both high-precision and safety of life in real time, WAPPS is facing urgent needs to improve its service integrity. This study presents a real-time integrity monitoring approach for WAPPS. Using dual-frequency ionosphere-free corrections of GPS and BDS, along with monitor station data, related error models are established and the integrity monitoring is achieved, based on the analysis of satellite corrected residuals. In addition, satellite faults are simulated for performance verification. The results show that the algorithm can monitor both step and drift faults effectively and alert users in time.

scholarly journals MODERNIZATION OF THE ESTONIAN NATIONAL GNSS REFERENCE STATION NETWORK

2018 ◽  
Vol 44 (2) ◽  
pp. 55-62 ◽  
Author(s):  
Jaanus Metsar ◽  
Karin Kollo ◽  
Artu Ellmann
Keyword(s):  
Real Time ◽  
Global Navigation Satellite System ◽  
Geodetic Network ◽  
Satellite System ◽  
Reference Station ◽  
Navigation Satellite ◽  
Station Network ◽  
The Real ◽  
Gnss Network ◽  
Global Navigation Satellite

The first GNSS (Global Navigation Satellite System) CORS (Continuously Operating Reference Station) in Estonia became operational in 1996. Starting from 2008 four Estonian CORS are incorporated into the EPN (EUREF Permanent GNSS Network). During the years 2014-2015 modernization of the GNSS CORS in Estonia was carried out. Currently the total number of the resulting ESTPOS reference stations is 28. These ESTPOS stations were interconnected to the I order national geodetic network by a special GNSS campaign in 2017. The maintenance and compilation of the ESTPOS based research products is explained. Aspects of the ESTPOS usage, including also the real time surveys, are discussed. Comparisons with SWEPOS (Swedish national GNSS CORS) and FinnRef (Finnish national GNSS CORS) networks indicate possibilities for further ESTPOS developments.

scholarly journals Multi-Layer Defences for Robust GNSS Timing Retrieval

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7787
Author(s):  
Ciro Gioia ◽  
Daniele Borio
Keyword(s):  
Global Navigation Satellite System ◽  
Interference Mitigation ◽  
Satellite System ◽  
Navigation Satellite ◽  
Integrity Monitoring ◽  
Gnss Receivers ◽  
Mitigation Techniques ◽  
Receiver Autonomous Integrity Monitoring ◽  
Global Navigation Satellite

A multi-layered interference mitigation approach can significantly improve the performance of Global Navigation Satellite System (GNSS) receivers in the presence of jamming. In this work, three levels of defence are considered including: pre-correlation interference mitigation techniques, post-correlation measurement screening and FDE at the Position, Velocity, and Time (PVT) level. The performance and interaction of these receiver defences are analysed with specific focus on Robust Interference Mitigation (RIM), measurement screening through Lock Indicator (LIs) and Receiver Autonomous Integrity Monitoring (RAIM). The case of timing receivers with a known user position and using Galileo signals from different frequencies has been studied with Time-Receiver Autonomous Integrity Monitoring (T-RAIM) based on the Backward-Forward method. From the experimental analysis it emerges that RIM improves the quality of the measurements reducing the number of exclusions performed by T-RAIM. Effective measurements screening is also fundamental to obtain unbiased timing solutions: in this respect T-RAIM can provide the required level of reliability.

Bayesian Fault-Tolerant Position Estimator and Integrity Risk Bound for GNSS Navigation

2014 ◽  
Vol 67 (5) ◽  
pp. 753-775 ◽  
Author(s):  
Fang-Cheng Chan ◽  
Mathieu Joerger ◽  
Samer Khanafseh ◽  
Boris Pervan
Keyword(s):  
Considerable Increase ◽  
Fault Tolerant ◽  
Satellite System ◽  
Substantial Improvement ◽  
Test Statistic ◽  
Prior Probabilities ◽  
Risk Bound ◽  
Receiver Autonomous Integrity Monitoring ◽  
Integrity Risk ◽  
Global Navigation Satellite

The advent of multiple Global Navigation Satellite System (GNSS) constellations will result in a considerable increase in the number of satellites for positioning worldwide. This substantial improvement in measurement redundancy has the potential to radically advance receiver autonomous integrity monitoring (RAIM) performance. However, regardless of the number of satellites, the performance of existing RAIM methods is sensitive to the assumed prior probabilities of individual fault hypotheses. In this paper, a new method is developed using Bayes’ theorem to generate upper bounds on posterior probabilities of individual fault hypotheses given current user measurements. These bounds are used in a Bayesian fault-tolerant position estimator (FTE) that minimizes integrity risk. The detection test statistic is a measurement-based integrity risk bound, which is directly compared with a pre-specified risk requirement. The associated challenge of quantifying continuity risk is resolved using a bounding approach, which is also detailed in this work. The new Bayesian FTE method is shown to be more robust to uncertainty in prior probability of fault occurrence than existing RAIM methods.

scholarly journals Methodology for the Correction of the Spatial Orientation Angles of the Unmanned Aerial Vehicle Using Real Time GNSS, a Shoreline Image and an Electronic Navigational Chart

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2810
Author(s):  
Krzysztof Naus ◽  
Piotr Szymak ◽  
Paweł Piskur ◽  
Maciej Niedziela ◽  
Aleksander Nowak
Keyword(s):  
Real Time ◽  
Spatial Orientation ◽  
Orientation Angle ◽  
Satellite System ◽  
Angle Measurement ◽  
Angle Correction ◽  
Lidar Measurements ◽  
Aerial Vehicle ◽  
Marine Applications ◽  
Global Navigation Satellite

Undoubtedly, Low-Altitude Unmanned Aerial Vehicles (UAVs) are becoming more common in marine applications. Equipped with a Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) receiver for highly accurate positioning, they perform camera and Light Detection and Ranging (LiDAR) measurements. Unfortunately, these measurements may still be subject to large errors-mainly due to the inaccuracy of measurement of the optical axis of the camera or LiDAR sensor. Usually, UAVs use a small and light Inertial Navigation System (INS) with an angle measurement error of up to 0.5∘ (RMSE). The methodology for spatial orientation angle correction presented in the article allows the reduction of this error even to the level of 0.01∘ (RMSE). It can be successfully used in coastal and port waters. To determine the corrections, only the Electronic Navigational Chart (ENC) and an image of the coastline are needed.

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