Reliability Monitoring of GNSS Aided Positioning for Land Vehicle Applications in Urban Environments
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5)µ4& &OWVFEFMPCUFOUJPOEV %0$503"5%&-6/*7&34*5²%&506-064& %ÏMJWSÏQBS Institut Supérieur de l’Aéronautique et de l’Espace 1SÏTFOUÏFFUTPVUFOVFQBS Khairol Amali BIN AHMAD le jeudi 11 juin 2015 5JUSF Surveillance de la fiabilité du positionnement par satellite (GNSS) pour les applications de véhicules terrestres dans les milieux urbains Reliability Monitoring of GNSS Aided Positioning for Land Vehicle Applications in Urban Environments ²DPMF EPDUPSBMF et discipline ou spécialité ED MITT : Réseaux, télécom, système et architecture 6OJUÏEFSFDIFSDIF Équipe d'accueil ISAE-ONERA SCANR %JSFDUFVS T EFʾÒTF M. Christophe MACABIAU (directeur de thèse) M. Mohamed SAHMOUDI (co-directeur de thèse) Jury : M. Michel BOUSQUET - Président M. David BÉTAILLE M. Philippe BONNIFAIT M. Roland CHAPUIS M. Maan EL-BADAOUI EL-NAJJAR - Rapporteur M. Bernd EISSFELLER - Rapporteur M. Christophe MACABIAU - Directeur de thèse M. Mohamed SAHMOUDI - Co-directeur de thèse Abstract This thesis addresses the challenges in reliability monitoring of GNSS aided navigation for land vehicle applications in urban environments. The main objective of this research is to develop methods of trusted positioning using GNSS measurements and confidence measures for the user in constrained urban environments. In the first part of the thesis, the NLOS errors in urban settings are characterized by means of a 3D model of the ur- ban surrounding. In an environment with limited number of visible satellites, excluding degraded signals could result in not having enough number of acceptable measurements for a position fix or adversely affect the satellites geometry. Using a GNSS simulator together with the 3D model, NLOS signals are identified and their biases are predicted. From this prediction, NLOS signals are corrected and used to improve the accuracy and integrity of the estimated positions. For the second part of the thesis, the work proposes a reliability monitoring technique in the range domain for urban environment using a trusted velocity sensor. The approach takes on pseudorange (PR) prediction using hybridization with other sensors. Single odometer and a gyro are used to obtain a reference position for reliability checking of GNSS pseudorange. By using the hybrid approach, residuals are generated and test statistic are calculated, and tested against a threshold. A few forms of residuals were derived based on several observables, namely the PR, the range rate and the velocity. Finally, the research developed a novel exper- imental scheme in integrity monitoring for positioning in urban environment. Working directly in the position domain, Horizontal Position Errors (HPE) are characterized us- ing generalized Pareto Distribution. Then, a test statistic is derived based on position residuals which CDF are mapped or inflated to match the characterized overbounding position error CDF. By monitoring the test statistic against a specific threshold, the positioning integrity and continuity are met at a certain level of confidence. In addition, the Horizontal Protection Level (HPL) computation using a composite approach has also been analysed. Acknowledgements I would like to express my sincere gratitude to those who have helped me in whatever ways along my journey to complete this thesis. I especially wish to acknowledge my two supervisors, Dr. Christophe Macabiau and Dr. Mohamed Sahmoudi, whom I am forever indebted, for making this research possible. Thank you both for the supervision, guidance and mentoring throughout the studies and also for the encouragement and providing insightful comments which are beneficial for the progress of the thesis. I would like to extend my thanks also to the jury members who have taken their time to review the thesis and shared their vast knowledge and experience in providing their comments and recommendations. My gratitude also goes to the colleagues and staffs of DEOS - Aude, Syed, Paulo, Cheng, Azeddine, Remy, Nabil, Quintin, Beno^ıt,Gael and others, - who in one way or another give me the sense of companionship and comradery that I am not alone in the struggle. And last but not least, to my beloved family - who had accompanied me with persever- ance along this arduous journey till the end. ii Contents Abstract i Acknowledgements ii List of Figures vii List of Tables xi Abbreviations xiii RESUM´ E´ DES TRAVAUX EN FRANC¸AIS1 1 Introduction 53 1.1 Motivation................................... 54 1.2 GNSS Systems Overview............................ 56 1.3 GNSS General Working Principle...................... 60 1.3.1 Pseudorange measurement and positioning............. 60 1.3.2 Doppler Measurement and its relation to range rate and carrier phase.................................. 63 1.3.3 Dilution of Precision (DOP) - Impact of Satellite-User Geometry on positioning.............................. 65 1.4 Navigation solution reliability performance in civil aviation........ 66 1.5 GNSS Augmentation System......................... 68 1.6 Integrity of GNSS Positioning......................... 70 1.7 Thesis objectives................................ 73 1.8 Thesis contributions.............................. 74 1.9 Thesis Structure................................ 75 1.10 List of Publications............................... 76 2 GNSS-based Navigation in Urban Environments: state-of-the-art 79 2.1 Positioning challenges in urban environments................ 80 2.1.1 Obstruction of satellite visibility................... 80 2.1.2 Multipath................................ 81 2.1.3 NLOS signal.............................. 82 2.2 Reliability needs of GNSS navigation for land applications......... 82 2.2.1 Impact of positioning integrity on the reliability of land application 85 2.3 Performance measures for land applications................. 86 2.4 Previous works on improving GNSS positioning Quality in Urban Envi- ronments.................................... 87 iii Contents iv 2.4.1 GNSS Errors Mitigation........................ 87 2.4.1.1 In receiver methods..................... 87 2.4.1.2 Hardware-based approaches................. 89 2.4.1.3 MP and NLOS modelling.................. 90 2.4.1.4 NLOS detection....................... 92 2.4.1.5 Constructive use of NLOS/MP............... 94 2.4.2 Hybridizations............................. 95 2.4.2.1 GNSS/DR Fusion...................... 96 2.4.2.2 Map matching........................ 98 2.4.2.3 GNSS/2D or 3D GIS Fusion................ 99 2.5 Conclusion................................... 100 3 Existing Works on Reliability and Integrity Monitoring of GNSS Po- sitioning 103 3.1 RAIM and Fault Detection.......................... 104 3.2 LSR RAIM................................... 104 3.2.1 Test Statistic.............................. 106 3.2.2 Detection Threshold.......................... 108 3.2.3 Relation between test statistic and position error.......... 109 3.2.4 Weighted LSR RAIM......................... 112 3.2.5 Slope based HPL............................ 113 3.3 Maximum Solution of Separation (MSS) RAIM............... 114 3.3.1 Test Statistic.............................. 115 3.3.2 Detection Threshold.......................... 115 3.3.3 HPL computation........................... 116 3.4 Benefits and Opportunity from Multi-constellation and multi-frequencies 117 3.5 Multiple Faults................................. 117 3.5.1 Iterative approach of multi-faults detection............. 119 3.5.2 Other approaches to deal with multiple faults............ 120 3.5.3 Slope-based HPL in multi-faults case................. 124 3.5.4 NIORAIM: HPL Optimisation.................... 125 3.5.5 Multiple Hypothesis Solution Separation (MHSS) RAIM...... 126 3.6 Error Overbounding.............................. 126 3.6.1 Range Domain Overbound...................... 128 3.6.2 Position Domain Overbound..................... 130 3.6.3 Parameter Inflation.......................... 130 3.6.4 Heavy Tail Overbounding....................... 131 3.7 Conclusion................................... 131 4 NLOS Characterization in Urban Environments Using a 3D Model 133 4.1 Introduction................................... 133 4.2 Predicting GNSS signal propagation conditions via 3D model....... 134 4.2.1 SE-NAV deterministic simulator of GNSS reception in urban en- vironment................................ 136 4.2.2 Reliability of 3D model for reception state prediction and NLOS bias prediction............................. 138 4.3 Proposed approach for positioning with NLOS signals........... 141 Contents v 4.3.1 LOS/NLOS pseudoranges measurements model........... 141 4.3.2 Integration of the 3D-based bias estimation in the PVT Kalman Filter.................................. 144 4.3.3 Data collection, equipment and software............... 146 4.4 Results and analysis.............................. 146 4.4.1 Estimation of Variance (C/No) Model Parameters......... 146 4.4.2 NLOS/LOS prediction by SE-NAV.................. 147 4.4.3 Results of the estimated position................... 149 4.4.4 Bias prediction by SE-NAV...................... 151 4.5 Conclusion................................... 153 5 Measurement Reliability via Pseudorange Prediction Using a Hybrid Approach 155 5.1 Introduction................................... 155 5.2 GNSS Quality control............................. 156 5.3 Hybrid navigation for vehicle in urban areas................. 158 5.4 Vehicle models................................. 160 5.5 Sensor configurations.............................. 164 5.6 Sensors fusion methods............................. 167 5.7 GNSS/Odometer/Gyro integration