IPNL Intelligent Positioning & Navigation Lab EN 简 繁
RESEARCH

Integrity, Fault Detection, and Safety-Quantifiable Localization

Navigation systems that estimate both state and trust — fault detection, non-Gaussian overbounding, protection-level computation, and integrity-constrained optimization for safety-critical autonomy.

navigation integrityfault detectionprotection leveloverboundingnon-Gaussian errorsintegrity-constrained FGOsafety-critical localizationspoofing detection

Pillar lead: Penggao Yan

Accuracy is not enough for safety-critical navigation: a confident answer in the wrong place is more dangerous than an honest “I don’t know.” This pillar builds systems that estimate not only where they are, but whether that answer can be trusted — outputting a state estimate and a quantified protection level together.

Conventional estimators output only a position with no measure of trust, dangerous for safety-critical autonomy; IPNL estimates state and trust together — fault detection, non-Gaussian overbounding and protection levels — and outputs a safety decision.

We develop fault detection, non-Gaussian error bounding, protection-level computation, and integrity-constrained optimization. Representative threads: Principal Gaussian Overbound for Heavy-tailed Error Bounding (Yan, Zhong, Hsu, IEEE TAES 2024), Integrity-Constrained Factor Graph Optimization (Xia, Wen, Hsu, NAVIGATION 2024), and Fault Detection for Gaussian Mixture Noises in Lidar/IMU Integrated Localization (Yan et al., NAVIGATION 2025).

This pillar is the technical core of the 2023 ION Per Enge Early Achievement Award and the RGC Research Impact Fund R5009-21 (HK$4.43M total (HK$3.1M RGC), Project Coordinator, 2021–2026).

Lab Contributors

Weisong Wen (11) Penggao Yan (7) Feng Huang (4) Bing Xu (3) Qian Meng (3) Jiachong Chang (2) Xiao Xia (2) Xiwei Bai (2) Yihan Zhong (2) Zhengdao Li (2) Baoshan Song (1) Guohao Zhang (1) Jiachen Zhang (1) Liang Zhang (1) Sai Hu (1) Yuan Li (1) Yuhao Zhang (1)

Related Projects

Related Publications

2026 (4)

journal Q1
Song, B., Giamou, M., Yan, P., Xia, C., & Hsu, L.-T. (2026).Certifiable Alignment of GNSS and Local Frames via Lagrangian Duality. IEEE Robotics and Automation Letters. https://doi.org/10.1109/LRA.2026.3693943
journal Q1
Yan, P., Zhan, X., Sun, R., & Hsu, L.-T. (2026).Credible Uncertainty Quantification Under Noise and System Model Mismatch in Localization Systems. IEEE Transactions on Instrumentation and Measurement. https://doi.org/10.1109/tim.2026.3682809
journal Q2
Yuan, Li, Yan, P., & Hsu, L.-T. (2026).Investigation of performance improvement in GNSS PPP-RTK ambiguity resolution. Advances in Space Research. https://doi.org/10.1016/j.asr.2026.01.099
journal Q1
Yan, P., Jin, R., Zhang, J., Wang, C.-W., & Hsu, L.-T. (2026).Jackknife ARAIM: Efficient GNSS Integrity Monitoring for Simultaneous Faults under Non-Gaussian Errors. Aerospace Systems. https://doi.org/10.1007/s42401-026-00457-2

2025 (6)

patent
Wang, Q, Huang, X, Shaheer, M, Mohammad, T, Zhang, X, Luo, M, Hsu, L. T, & Usmani, A (2025).Indoor Fire Monitoring Based on Look-Up-From-Floor Sensing of Ceiling (granted) (US 12,292,340 B2). U.S. Patent and Trademark Office. https://patents.google.com/patent/US12292340B2
journal Q1
Yan, P., Hu, Y., Wen, W., & Hsu, L. T. (2025).Multiple Faults Isolation For Multi-Constellation GNSS Positioning through Incremental Expansion of Consistent Measurements. IEEE Sensors Journal. https://doi.org/10.1109/jsen.2024.3524434
journal Q1
Yan, P., Li, Z., Huang, F., Wen, W., & Hsu, L. T. (2025).Fault Detection Algorithm for Gaussian Mixture Noises: An Application in Lidar/IMU Integrated Localization Systems. NAVIGATION: Journal of the Institute of Navigation. https://doi.org/10.33012/navi.684
journal Q1
Zheng, X., Wen, W., & Hsu, L. T. (2025).Safety-quantifiable line feature-based monocular visual localization with 3d prior map. IEEE Transactions on Intelligent Transportation Systems. https://doi.org/10.1109/tits.2025.3572620
conference
Zhengdao, Li, Yan, P., Wen, W., & Hsu, L.-T. (2025).Paired Cauchy-Gaussian overbound for not symmetric unimodal heavy-tailed distributions. 2025 IEEE/ION Position, Location and Navigation Symposium (PLANS). https://doi.org/10.1109/PLANS61210.2025.11028215
conference
Song, B., Wen, W., & Hsu, L.-T. (2025).Certifiably Optimal Satellite Orbit Determination Based on Doppler Measurements for Low-Earth-Orbit Satellites. 2025 IEEE/ION Position, Location and Navigation Symposium (PLANS). https://doi.org/10.1109/PLANS61210.2025.11028259

2024 (9)

patent
Wang, Q, Huang, X, Shaheer, M, Mohammad, T, Zhang, X, Luo, M, Hsu, L. T, X, W., Xiao, F, & Usmani, A (2024).Indoor Fire Monitoring Based on Look-Up-From-Floor Sensing of Ceiling (US 2023/0062745 A1). U.S. Patent and Trademark Office. https://patents.google.com/patent/US20230062745A1
patent
Wang, Q, Huang, X, Shaheer, M, Mohammad, T, Zhang, X, Luo, M, Hsu, L. T, X, W., Xiao, F, & Usmani, A (2024).Indoor Fire Monitoring Based on Look-Up-From-Floor Sensing of Ceiling (granted) (ZL 202211006213.6). China National Intellectual Property Administration (CNIPA).
patent
Wang, Q, Huang, X, Shaheer, M, Mohammad, T, Zhang, X, Luo, M, Hsu, L. T, X, W., Xiao, F, & Usmani, A (2024).Indoor Fire Monitoring Based on Look-Up-From-Floor Sensing of Ceiling (granted) (US 11,860,043 B2). U.S. Patent and Trademark Office. https://patents.google.com/patent/US11860043B2
journal Q1
Yan, P., Zhong, Y., & Hsu, L. T. (2024).Principal Gaussian Overbound for Heavy-tailed Error Bounding. IEEE Transactions on Aerospace and Electronic Systems. https://doi.org/10.1109/taes.2024.3448405
journal Q1
Yan, P., Xia, X., Brizzi, M., Wen, W., & Hsu, L. T. (2024).Subspace-based Adaptive GMM Error Modeling for Fault-Aware Pseudorange-based Positioning in Urban Canyons. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2024.3450198
journal Q1
Xia, X., Wen, W., & Hsu, L. T. (2024).Integrity-Constrained Factor Graph Optimization for GNSS Positioning in Urban Canyons. NAVIGATION: Journal of the Institute of Navigation. https://doi.org/10.33012/navi.660
journal Q1
Zhang, J., Liu, X., Wen, W., & Hsu, L. T. (2024).Safety-Quantifiable Planar-Feature-based LiDAR Localization with a Prior Map for Intelligent Vehicles in Urban Scenarios. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2024.3467115
conference
Yan, P., Zhong, Y., & Hsu, L.-T. (2024).Bounding the Heavy-Tailed Pseudorange Error by Leveraging Membership Weights Analysis of Gaussian Mixture Model. ION Pacific PNT. https://doi.org/10.33012/2024.19604
conference
Yan, P., Wen, W., Huang, F., & Hsu, L.-T. (2024).A Fault Detection Algorithm for LiDAR/IMU Integrated Localization Systems with Non-Gaussian Noises. The International Technical Meeting of the The Institute of Navigation. https://doi.org/10.33012/2024.19564

2023 (5)

patent
Meng, Q& Hsu, L. T (2023).Integrity Monitoring Method, Apparatus and Electronic Device for Navigation Systems (导航系统的完好性监测方法、完好性监测装置及电子设备, granted) (ZL 202010387470.3). China National Intellectual Property Administration (CNIPA).
journal Q1
Chang, J., Huang, F., Zhang, L., Xu, D., & Hsu, L. T. (2023).Selection of Areas for Effective GNSS Spoofing Attacks to a Vehicle-mounted MSF System based on Scenario Classification Models. IEEE Transactions on Vehicular Technology. https://doi.org/10.1109/tvt.2023.3279831
journal Q1
Zhang, Z., Li, Y., He, X., & Hsu, L. (2023).Resilient GNSS real-time kinematic precise positioning with inequality and equality constraints. GPS Solutions. https://doi.org/10.1007/s10291-023-01454-0
journal Q1
Fang, J., Yue, J., Xu, B., & Hsu, L. T. (2023).A post-correlation graphical way for continuous GNSS spoofing detection. Measurement. https://doi.org/10.1016/j.measurement.2023.112974
journal Q1
Chang, J., Zhang, Y., Fan, S., Huang, F., Xu, D., & Hsu, L. T. (2023).An Anti-spoofing Model based on MVM and MCCM for a Loosely-coupled GNSS/INS/LiDAR Kalman Filter. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2023.3335356

2022 (2)

patent
Meng, Q, Hsu, L. T, & B, X. (2022).Spoofing Signal Generation Method and Apparatus (欺骗信号生成方法及装置, granted) (ZL 201910778721.8). China National Intellectual Property Administration (CNIPA).
journal Q1
Meng, Q. and Hsu L. T. (2022).Resilient Interactive Sensor-Independent-Update Fusion Navigation Method. IEEE Transactions on Intelligent Transportation Systems. https://doi.org/10.1109/tits.2022.3150273

2021 (2)

journal unranked
S., H., Kan, Y.C., & Hsu, L.T. (2021).Localization Uncertainty Constrained Lateral PID Control with Aids of Fuzzy Logic Considering LiDAR NDT Matching Error. Journal of Aeronautics, Astronautics and Aviation, Series A.
journal Q1
Bai, X., Wen, W., & Hsu, L. T. (2021).Degeneration-aware Outlier Mitigation for Visual Inertial Integrated Navigation System in Urban Canyons. IEEE Transactions on Instrumentation and Measurement. https://doi.org/10.1109/tim.2021.3126010

2020 (3)

journal Q3
El-Mowafy, A., B., X., & Hsu, L. T. (2020).Integrity Monitoring of multi-GNSS SPP and DGNSS in Urban Environment using ARAIM and 3D City Models. Journal of Spatial Science.
journal Q3
Meng, Q.& Hsu, L. T. (2020).Integrity for Autonomous Vehicles and Towards a Novel Alert Limit Determination Method. Proc. IMechE, Part D: Journal of Automobile Engineering. https://doi.org/10.1177/0954407020965760
journal Q1
Meng, Q.& Hsu, L. T. (2020).Integrity Monitoring for All-Source Navigation Enhanced by Kalman Filter-Based Solution Separation. IEEE Sensors Journals. https://doi.org/10.1109/jsen.2020.3026081

2019 (2)

journal Q3
Wen, W., Bai, X., Zhan, W., Tomizuka, M., & Hsu, L. T. (2019).Uncertainty Estimation of LiDAR Matching Aided by Dynamic Vehicle Detection and High Definition Map. IET Electronics Letters. https://doi.org/10.1049/el.2018.8075
journal Q2
Meng, Q., Hsu, L. T., B., X., Luo, X., & El-Mowafy, A. (2019).A GPS Spoofing Generator using an Open Sourced Vector Tracking-Based Receiver. Sensors. https://doi.org/10.3390/s19183993

2018 (1)

journal Q2
Zhang, G.& Hsu, L.T. (2018).A New Path Planning Algorithm Using GNSS Localization Error Map for UAV in Urban Area. Journal of Intelligent & Robotic Systems. https://doi.org/10.1007/s10846-018-0894-5

2017 (1)

journal Q1
Hsu, L. T., Tokura, H., Kubo, N., Y., G., & Kamijo, S. (2017).Multiple Faulty GNSS Measurement Exclusion based on Consistency Check in Urban Canyons. IEEE Sensors Journal. https://doi.org/10.1109/jsen.2017.2654359

2010 (1)

journal unranked
Tao, A. L., Hsu, L. T., & Jan, S. S. (2010).Wide Area Differential GNSS in Taiwan: Development and Validation Testing. Journal of Aeronautics, Astronautics and Aviation, Series A.