Optimization-Based Estimation and Factor Graphs

factor graph optimizationFGOGNSS/INSRTKPPP-RTKsmoothingnonlinear optimizationrobust estimationsensor fusion

Pillar lead: Weisong Wen

Factor graph optimization is the mathematical engine that links signals, measurements, maps, sensors, and integrity. We use it as a unifying framework — letting navigation systems reason over time, fuse heterogeneous measurements, and handle outliers more flexibly than classical filtering-only pipelines.

The Extended Kalman Filter condenses all history into one current state with a single linearization and handles outliers poorly; IPNL uses factor graph optimization to jointly optimize a window of states over time and fuse heterogeneous measurements into a robust trajectory.

The foundational paper Factor Graph Optimization for GNSS/INS Integration: A Comparison with the Extended Kalman Filter (Wen, Pfeifer, Bai, Hsu, NAVIGATION 2021) was named the 2024 Most-Cited Paper in NAVIGATION: Journal of the Institute of Navigation. The follow-on work extends FGO into integrity-constrained estimation, smartphone IMU-only indoor SLAM (IEEE TAES 2024), 3D vision-aided GNSS RTK (NAVIGATION 2023), and self-supervised weighting (AutoW, ION GNSS+ 2024). The open-source GraphGNSSLib library is the community-facing artifact of this pillar.

Related Projects

Multi-Agent Collaborative GNSS for Intelligent Transportation Systems completed
UrbanNav active
LunaNav: Lunar Robotic Exploration active
Robust GNSS Navigation for Urban Air Traffic Management active
GraphGNSSLib active
Universal Vehicle Self-Diagnosis: Predictive Component Monitoring active
3D Map-Aided GNSS (3DMA) for Smartphone and IoT active
Environment-Aware GNSS for UAS and Autonomous Driving active
Precision Start-Gate Monitoring for Olympic-Class Windsurfing active

Related Publications

2026 (4)

patent

Hsu, L. T& Wen, W (2026).3D LiDAR Aided GNSS and the Method for NLOS Detection and Correction (CA 3,156,087). Canadian Intellectual Property Office (CIPO).

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

Che, D., Hua, L., Hou, P., Hsu, L.-T., Fei, Ye, & Zhang, B. (2026).Single-frequency RTK positioning in the presence of ambiguity-like code biases. Measurement. https://doi.org/10.1016/j.measurement.2026.120370

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

2025 (15)

book

Hsu, L. T., Zhang, G., & F., N. H. (2025).Chapter: Map-Aided GNSS Positioning. Springer Publishers Inc.

book

Hsu, L. T., Zhang, G., & Wen, W. (2025).Principles of Indoor Positioning and Indoor Navigation. Artech House Publishers Inc.

Code

patent

Hsu, L. T& Wen, W (2025).3D LiDAR Aided GNSS and the Method for NLOS Detection and Correction (ZL 2022 1 0905688.2). China National Intellectual Property Administration (CNIPA).

patent

Hsu, L. T& Wen, W (2025).3D LiDAR Aided GNSS and the Method for NLOS Detection and Correction (HK 40077647). Hong Kong Intellectual Property Department.

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

Bai, S., Wen, W., Su, D., & Hsu, L. T. (2025).Graph-Based Indoor 3D Pedestrian Location Tracking With Inertial-Only Perception. IEEE Transactions on Mobile Computing. https://doi.org/10.1109/tmc.2025.3526196

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

Ng, H. F., Zhong, Q., Groves, P., & Hsu, L. T. (2025).Grid-based 3DMA GNSS with clustering and Doppler velocity using factor graph optimisation. The Journal of Navigation. https://doi.org/10.1017/s0373463325000220

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

journal Q1

Liu, X., Wen, W., Huang, F., Gao, H., Wang, Y., & Hsu, L. T. (2025).3-D LiDAR-Aided GNSS NLOS Mitigation for Reliable GNSS-RTK Positioning in Urban Canyons. IEEE Transactions on Instrumentation and Measurement. https://doi.org/10.1109/tim.2025.3629836

journal Q1

Yang, P., Wen, W., Bai, S., & Hsu, L. T. (2025).Tightly joined positioning and control model for unmanned aerial vehicles based on factor graph optimization. IEEE Transactions on Vehicular Technology. https://doi.org/10.1109/tvt.2025.3589556

journal Q1

Liu, X., Wen, W., Zhang, L., & Hsu, L. T. (2025).3D LiDAR Aided GNSS NLOS Correction by Direction-of-Arrival Estimation Using Doppler Measurements in Urban Canyons. IEEE Transactions on Intelligent Transportation Systems. https://doi.org/10.1109/tits.2025.3596582

conference

Huang, F., Zhong, Y., Chen, H., Dongzhe, Su, Jin, Wu, Wen, W., & Hsu, L.-T. (2025).Roadside GNSS Aided Multi-Sensor Integrated System for Vehicle Positioning in Urban Areas. 2025 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). https://doi.org/10.1109/IROS60139.2025.11246475

conference

Zhong, Y., Hoi-Fung, Ng, Hsu, L.-T., & Wen, W. (2025).GNSS/Map Integration with Batch Factor Graph Optimization for Reliable Trajectory Estimation in Urban Canyon. 2025 IEEE/ION Position, Location and Navigation Symposium (PLANS). https://doi.org/10.1109/PLANS61210.2025.11028209

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 (23)

patent

Hsu, L. T& Wen, W (2024).3D LiDAR Aided GNSS and the Method for NLOS Detection and Correction (US 12,123,961 B2). U.S. Patent and Trademark Office. https://patents.google.com/patent/US12123961B2

journal Q1

Xin, S., Geng, J., & Hsu, L. T. (2024).Factor Graph Optimization-based GNSS PPP-RTK: An Alternative Platform to Study Urban GNSS Precise Positioning. IEEE Transactions on Aerospace and Electronic Systems. https://doi.org/10.1109/taes.2024.3360380

journal Q1

Iyer, K., Dey, A., Xu, B., Sharma, N., & Hsu, L. T. (2024).Enhancing positioning in GNSS denied environments based on an extended Kalman filter using past GNSS measurements and IMU. IEEE Transactions on Vehicular Technology. https://doi.org/10.1109/tvt.2024.3360076

journal Q1

Zhong, Y., Hu, R., Bai, X., Li, X., Hsu, L. T., & Wen, W. (2024).Enhancing GNSS Positioning Accuracy for Road Monitoring Systems: A Factor Graph Optimization Approach Aided by Geospatial Information. IEEE Transactions on Instrumentation and Measurement. https://doi.org/10.1109/tim.2024.3369156

journal Q1

Xu, P., Zhang, G., Zhong, Y., Yang, B., & Hsu, L. T. (2024).A Framework for Graphical GNSS Multipath and NLOS Mitigation. IEEE Transactions on Intelligent Transportation Systems. https://doi.org/10.1109/tits.2024.3374819

journal Q1

Vicenzo, S., Xu, B., Xu, H., & Hsu, L. T. (2024).GNSS direct position estimation-inspired positioning with pseudorange correlogram for urban navigation. GPS Solutions. https://doi.org/10.1007/s10291-024-01627-5

journal Q1

Zhang, L., Ng, H. F., Zhang, G., & Hsu, L. T. (2024).Ray-Tracing Correction for GNSS Velocity Estimation Using Doppler Frequency: A Feasibility Analysis. IEEE Transactions on Instrumentation and Measurement. https://doi.org/10.1109/tim.2024.3385033

journal Q1

Zhong, Y., Wen, W., & Hsu, L. T. (2024).Trajectory Smoothing Using GNSS/PDR Integration Via Factor Graph Optimization in Urban Canyons. IEEE Internet of Things Journal. https://doi.org/10.1109/jiot.2024.3396360

journal Q1

Jin, R., Zhang, G., Hsu, L. T., & Hu, Y. (2024).A Survey on Cooperative Positioning Using GNSS Measurements. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2024.3397879

journal Q1

Bai, X.& Hsu, L. T. (2024).GNSS/Visual/IMU/Map Integration Via Sliding Window Factor Graph Optimization for Vehicular Positioning in Urban Areas. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2024.3412208

journal Q1

Zheng, X., Wen, W., & Hsu, L. T. (2024).Tightly-coupled visual/inertial/map integration with observability analysis for reliable localization of intelligent vehicles. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2024.3419101

journal Q1

Bai, S., Wen, W., Hsu, L. T., & Yang, P. (2024).Factor Graph Optimization-Based Smartphone IMU-Only Indoor SLAM With Multi-Hypothesis Turning Behavior Loop Closures. IEEE Transactions on Aerospace and Electronic Systems. https://doi.org/10.1109/taes.2024.3430256

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

journal Q?

Ho, H. Y., Ng, H. F., Wen, W., Gu, Y., & Hsu, L. T. (2024).Enhancing Smartphone-based Pedestrian Positioning: Using Factor Graph Optimization with Indoor/Outdoor Detection for 3DMA GNSS/Visual-Inertial State Estimation. Journal of Data Science and Intelligent Systems. https://doi.org/10.47852/bonviewjdsis42022961

journal Q1

Zhang, L., Ng, H. F., Zhong, Y., Zhang, G., & Hsu, L. T. (2024).GNSS Doppler Velocity Estimation Aided by 3D Mapping Database. IEEE Transactions on Intelligent Transportation Systems. https://doi.org/10.1109/tits.2024.3486448

conference

Bai, S., Wen, W., Yue, Yu, & Hsu, L.-T. (2024).Invariant Extended Kalman Filtering for Pedestrian Deep-Inertial Odometry. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. https://doi.org/10.5194/isprs-archives-xlviii-4-2024-607-2024

conference

Penghui, Xu& Hsu, L.-T. (2024).AutoW: Self-Supervision Learning for Weighting Estimation in GNSS Positioning. ION GNSS+, The International Technical Meeting of the Satellite Division of The Institute of Navigation. https://doi.org/10.33012/2024.19896

conference

Hoi-Fung, Ng, Penghui, Xu, Zhong, Y., Zhang, G., Wen, W., & Hsu, L.-T. (2024).DGNSS Corrected Pseudorange and Time-Differenced Carrier Phase (TDCP) Measurements using Differentiable Factor Graph Optimization (DFGO). ION GNSS+, The International Technical Meeting of the Satellite Division of The Institute of Navigation. https://doi.org/10.33012/2024.19908

conference

Vicenzo, S., Xin, Qi, Bing, Xu, & Hsu, L.-T. (2024).Machine Learning Assisted GNSS Direct Position Estimation for Urban Environments Applications. The International Technical Meeting of the The Institute of Navigation. https://doi.org/10.33012/2024.19567

conference

Yuan, Li, Liu, X., Wen, W., Hsu, L.-T., Yuan, Y., Bian, G., & Chen, Q. (2024).Factor Graph Optimization Based Multi Epoch Ambiguity Resolution for GNSS RTK and its Evaluation in Hong Kong Urban Canyons. ION GNSS+, The International Technical Meeting of the Satellite Division of The Institute of Navigation. https://doi.org/10.33012/2024.19805

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

conference

Meiling, Su, Wang, B., Ahad, S., Huang, X., Zhang, G., & Hsu, L.-T. (2024).An Adaptive Weighted GNSS/VINS/Wi-Fi RTT-based Seamless Positioning System for Smartphone. 2024 14th International Conference on Indoor Positioning and Indoor Navigation (IPIN). https://doi.org/10.1109/IPIN62893.2024.10786175

2023 (23)

patent

Gong, Z, Bao, X, B, Y., Y, G., Hsu, L. T, & Wen, W (2023).Vehicle Position Enhancement System and Method (车载位置增强系统及方法) (CN 202310289415.4). China National Intellectual Property Administration (CNIPA). https://patents.google.com/patent/CN116660938A

journal Q3

Zhong, Y., Huang, F., Zhang, J., Wen, W., & Hsu, L. T. (2023).Low‐cost solid‐state LiDAR/inertial‐based localization with prior map for autonomous systems in urban scenarios. IET Intelligent Transport Systems. https://doi.org/10.1049/itr2.12273

journal Q1

Yan, P., Wen, W., & Hsu, L. T. (2023).Integration of Vehicle Dynamic Model and System Identification Model for Extending the Navigation Service Under Sensor Failures. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2023.3273185

journal Q1

Zhang, L., Wen, W., Hsu, L. T., & Zhang, T. (2023).An Improved Inertial Preintegration Model in Factor Graph Optimization for High Accuracy Positioning of Intelligent Vehicles. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2023.3282623

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

Chang, J., Hu, R., Huang, F., Xu, D., & Hsu, L. T. (2023).LiDAR-based NDT Matching Performance Evaluation for Positioning in Adverse Weather Conditions. IEEE Sensors Journal. https://doi.org/10.1109/jsen.2023.3312911

journal Q1

Wen, W., Bai, X., & Hsu, L. T. (2023).3D Vision Aided GNSS Real-Time Kinematic Positioning for Autonomous Systems in Urban Canyons. NAVIGATION: Journal of the Institute of Navigation. https://doi.org/10.33012/navi.590

journal Q1 Featured

Liu, X., Wen, W., & Hsu, L. T. (2023).GLIO: Tightly-coupled gnss/lidar/imu integration for continuous and drift-free state estimation of intelligent vehicles in urban areas. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2023.3323648

journal Q1 Featured

Xu, P., Zhang, G., Yang, B., & Hsu, L. T. (2023).PositionNet: CNN-based GNSS positioning in urban areas with residual maps. Applied Soft Computing. https://doi.org/10.2139/ssrn.4194604

journal Q1

Huang, F., Wen, W., Zhang, J., Wang, C., & Hsu, L. T. (2023).Dynamic Object-aware LiDAR Odometry Aided by Joint Weightings Estimation in Urban Areas. IEEE Transactions on Intelligent Vehicles. https://doi.org/10.1109/tiv.2023.3338141

journal Q1 Featured

Hsu, L. T., Huang, F., Ng, H. F., Zhang, G., Zhong, Y., Bai, X., & Wen, W. (2023).Hong Kong UrbanNav: An open-source multisensory dataset for benchmarking urban navigation algorithms. NAVIGATION: Journal of the Institute of Navigation. https://doi.org/10.33012/navi.602

journal Q1

Ng, H. F., Hsu, L. T., & Zhang, G. (2023).Multi-Epoch Kriging-Based 3D Mapping-Aided GNSS and Doppler Measurement Fusion using Factor Graph Optimization. NAVIGATION: Journal of the Institute of Navigation. https://doi.org/10.33012/navi.617

journal Q1

Li, Z., Lee, P. H., Hung, T. H. M., Zhang, G., & Hsu, L. T. (2023).Intelligent Environment-Adaptive GNSS/INS Integrated Positioning with Factor Graph Optimization. Remote Sensing. https://doi.org/10.3390/rs16010181

conference

Zheng, Xi, Wen, W., & Hsu, L.-T. (2023).Tightly-coupled Line Feature-aided Visual Inertial Localization within Lightweight 3D Prior Map for Intelligent Vehicles. 2023 IEEE 26th International Conference on Intelligent Transportation Systems (ITSC). https://doi.org/10.1109/itsc57777.2023.10422196

conference

Huang, F., Chen, H., Urtay, A., Dongzhe, Su, Wen, W., & Hsu, L.-T. (2023).Roadside Infrastructure assisted LiDAR/Inertial-based Mapping for Intelligent Vehicles in Urban Areas. 2023 IEEE 26th International Conference on Intelligent Transportation Systems (ITSC). https://doi.org/10.1109/itsc57777.2023.10422552

conference

Bai, X.& Hsu, L.-T. (2023).GVIM: GNSS/Visual/IMU/Map Integration Via Sliding Window Factor Graph Optimization in Urban Canyons. Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023). https://doi.org/10.33012/2023.19458

conference

Bai, S., Wen, W., Hsu, L.-T., & Yue, Yu (2023).Factor Graph Optimization-based Indoor Pedestrian SLAM with Probabilistic Exact Activity Loop Closures using Smartphone. 2023 13th International Conference on Indoor Positioning and Indoor Navigation (IPIN). https://doi.org/10.1109/ipin57070.2023.10332510

conference

Vicenzo, S., Bing, Xu, Dey, A., & Hsu, L.-T. (2023).Experimental Investigation of GNSS Direct Position Estimation in Densely Urban Area. Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023). https://doi.org/10.33012/2023.19341

conference

Penghui, Xu, Hoi-Fung, Ng, Zhong, Y., Zhang, G., Wen, W., Yang, Bo, & Hsu, L.-T. (2023).Differentiable Factor Graph Optimization with Intelligent Covariance Adaptation for Accurate Smartphone Positioning. Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023). https://doi.org/10.33012/2023.19297

conference

Huang, F., Wen, W., Zhang, G., Dongzhe, Su, & Hsu, L.-T. (2023).Adaptive Multi-Sensor Integrated Navigation System Aided by Continuous Error Map from RSU for Autonomous Vehicles in Urban Areas. 2023 IEEE 26th International Conference on Intelligent Transportation Systems (ITSC). https://doi.org/10.1109/itsc57777.2023.10422216

conference

Zhang, H., Wen, W., & Hsu, L.-T. (2023).A New GNSS Ambiguity Resolution Method Through Mixed Integer Programming. Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023). https://doi.org/10.33012/2023.19317

conference

Zhang, L., Hoi-Fung, Ng, Zhang, G., & Hsu, L.-T. (2023).3D Mapping Aided GNSS Positioning Using Doppler Frequency for Urban Areas. Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023). https://doi.org/10.33012/2023.19340

conference

Liu, X., Wen, W., & Hsu, L.-T. (2023).3D LiDAR Aided GNSS NLOS Correction with Direction of Arrival Estimation Using Doppler Measurements. Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023). https://doi.org/10.33012/2023.19447

2022 (8)

patent

Hsu, L. T& Wen, W (2022).3D LiDAR Aided GNSS and the Method for NLOS Detection and Correction (US 2023/0033404 A1). U.S. Patent and Trademark Office. https://patents.google.com/patent/US20230033404A1

journal Q1

Wen, W., Zhang, G., & Hsu, L. T. (2022).GNSS Outlier Mitigation via Graduated Non-Convexity Factor Graph Optimization. IEEE Transactions on Vehicular Technology. https://doi.org/10.1109/tvt.2021.3130909

journal Q1

Bai, X., Wen, W., & Hsu, L. T. (2022).Time-correlated Window Carrier-phase Aided GNSS Positioning Using Factor Graph Optimization for Urban Positioning. IEEE Transactions on Aerospace and Electronic Systems. https://doi.org/10.1109/taes.2022.3149730

journal Q2

Zhang, J, Wen, W, Huang, F, Wang, Y, Chen, X, & Hsu, L. T. (2022).GNSS-RTK Adaptively Integrated with LiDAR/IMU Odometry for Continuously Global Positioning in Urban Canyons. Applied Sciences. https://doi.org/10.3390/app12105193

journal Q1

Zhang, L.& Hsu, L. T. and Zhang T. (2022).A Novel INS/USBL Integrated Navigation Scheme Via Factor Graph Optimization. IEEE Transactions on Vehicular Technology. https://doi.org/10.1109/tvt.2022.3177739

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

journal Q1

Wen, W.& Hsu, L. T. (2022).AGPC-SLAM: Absolute Ground Plane Constrained 3D LiDAR SLAM. NAVIGATION: Journal of the Institute of Navigation. https://doi.org/10.33012/navi.527

conference

Liu, X., Wen, W., & Hsu, L.-T. (2022).3D LiDAR Aided GNSS Real-time Kinematic Positioning via Coarse-to-fine Batch Optimization for High Accuracy Mapping in Dense Urban Canyons. Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022). https://doi.org/10.33012/2022.18545

2021 (10)

patent

Zhang, G& Hsu, L. T (2021).3D map-aided GNSS cooperative positioning method and system (ZL 201910866398.X). China National Intellectual Property Administration. https://patents.google.com/patent/CN110426717B

journal Q2

Kan, Y.C., Hsu, L. T., & Chung, E. (2021).Performance Evaluation on Map-based NDT Scan Matching Localization using Simulated Occlusion Datasets. IEEE Sensors Letter. https://doi.org/10.1109/lsens.2021.3060097

journal Q1

Jiang, C., B., X., & Hsu, L. T. (2021).A Probabilistic Approach to Detect and Mitigate GNSS NLOS Using State Augmented Kalman Filter. GPS Solutions. https://doi.org/10.1007/s10291-021-01101-6

journal Q1 Featured

Wen, W., Pfeifer, T., Bai, X., & Hsu, L. T. (2021).Factor Graph Optimization for GNSS/INS Integration: A Comparison with the Extended Kalman Filter. NAVIGATION: Journal of the Institute of Navigation. https://doi.org/10.1002/navi.421

journal Q1

Zhang, J., Wen, W., Huang, F., & Hsu, L. T. (2021).Coarse-to-Fine Loosely-Coupled LiDAR-Inertial Odometry for Urban Positioning and Mapping. Remote Sensing. https://doi.org/10.3390/rs13122371

journal Q1

Yang, S.& Hsu, L.T. (2021).Tightly Coupled Integrated Navigation System Via Factor Graph for UAV Indoor Localization. Aerospace Science and Technology. https://doi.org/10.1016/j.ast.2020.106370

journal Q2

Luo, H., Y., L., Wang, J., Weng, D., J., Y., Hsu, L. T., & Chen, W. (2021).Integration of GNSS and BLE Technology With Inertial Sensors for Real-Time Positioning in Urban Environments. IEEE Access. https://doi.org/10.1109/access.2021.3052733

journal Q1

Yue, J., Wen, W., Han, J., & Hsu, L. T. (2021).3D Point Clouds Data Super Resolution Aided LiDAR Odometry for Vehicular Positioning in Urban Canyons. IEEE Transactions on Vehicular Technology. https://doi.org/10.1109/tvt.2021.3069212

journal Q1 Featured

H.F., N.& Hsu, L.T. (2021).3D Mapping Database Aided GNSS RTK and Its Assessments in Urban Canyons. IEEE Transactions on Aerospace and Electronic Systems. https://doi.org/10.1109/taes.2021.3069271

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 (7)

journal Q1

Chiang, K. W., H., L. Y., Hsu, L. T., & Chu, F. Y. (2020).The Design a TDCP-Smoothed GNSS/Odometer Integration Scheme with Vehicular-Motion Constraint and Robust Regression. Remote Sensing. https://doi.org/10.3390/rs12162550

journal Q1

Bai, X., Wen, W., & Hsu, L. T. (2020).Robust Visual-Inertial Integrated Navigation System Aided by Online Sensor Model Adaption for Autonomous Ground Vehicles in Urban Areas. Remote Sensing. https://doi.org/10.20944/preprints202003.0018.v1

journal Q1

Wen, W., Zhang, G., & Hsu, L. T. (2020).Object Detection Aided GNSS and Its Integration with LiDAR in Highly Urbanized Areas. IEEE Intelligent Transportation Systems Magazine. https://doi.org/10.1109/mits.2020.2994131

journal Q1

F., N. H., Zhang, G., & Hsu, L. T. (2020).A Computation Effective Range-Based 3D Mapping Aided GNSS with NLOS Correction Method. Journal of Navigation. https://doi.org/10.1017/s037346332000003x

journal Q2

Wen, W., Bai, X., Zhang, G., Chen, S., Yuan, F., & Hsu, L. T. (2020).Multi-Agent Collaborative GNSS/Camera/INS Integration Aided by Inter-ranging for Vehicular Navigation in Urban Areas. IEEE Access. https://doi.org/10.1109/access.2020.3006210

journal Q1

Zhang, G., Wen, W. Xu B., & Hsu, L. T. (2020).Extending Shadow Matching to Tightly-Coupled GNSS/INS Integration System. IEEE Transactions on Vehicular Technology. https://doi.org/10.1109/tvt.2020.2981093

journal Q1

Zhang, G., F., N. H., & Hsu, L. T. (2020).3D Mapping Database Aided GNSS Based Collaborative Positioning Using Factor Graph Optimization. IEEE Transactions on Intelligent Transportation Systems. https://doi.org/10.1109/tits.2020.2988531

2019 (4)

book

Hsu, L. T., Wen, W., & Zhang, G (2019).Chapter 2 - Vehicular Positioning System. Nova Science Publishers Inc.

journal Q1

Wen, W., Zhang, G., & Hsu, L. T. (2019).Correcting NLOS by 3D LiDAR and building height to improve GNSS single point positioning. NAVIGATION: Journal of the Institute of Navigation. https://doi.org/10.1002/navi.335

journal Q1

Wen, W., Bai, X., Kan, Y.C., & Hsu, L. T. (2019).Tightly Coupled GNSS/INS Integration Via Factor Graph and Aided by Fish-eye Camera. IEEE Transactions on Vehicular Technology. https://doi.org/10.1109/tvt.2019.2944680

journal Q1

B., X.& Jia, Q. and Hsu L. T. (2019).Vector Tracking Loop-based GNSS NLOS Detection and Correction: Algorithm Design and Performance Analysis. IEEE Transactions on Instrumentation and Measurement. https://doi.org/10.1109/tim.2019.2950578

2018 (3)

patent

Wang, Y& Hsu, L. T (2018).Positioning method and electronic equipment (CN 111198389B). China National Intellectual Property Administration. https://patents.google.com/patent/CN111198389B

journal Q1

Zhang, G.& Hsu, L. T. (2018).Intelligent GNSS/INS Integrated Navigation System for a Commercial UAV Flight Control System. Aerospace Science and Technology. https://doi.org/10.1016/j.ast.2018.07.026

journal Q2

Wen, W., Hsu, L. T., & Zhang, G. (2018).Performance analysis of NDT-based graph slam for autonomous vehicle in diverse typical driving scenarios of Hong Kong. Sensors. https://doi.org/10.3390/s18113928