Unsigned-Long

I'm currently a master candidate at the School of Geodesy and Geomatics (SGG), Wuhan University (WHU). My area of research currently focuses on integrated navigation systems and multi-sensor fusion. I'm working on the continue-time-based (B-spline-based) state estimation currently 😃.

About Me

Student at Wuhan University, E-Mail: shlchen@whu.edu.cn.
A brief introduction about me can be found here.
I love photography, I also love writing cpp (cplusplus) and creating funny toy libraries.
Ask me about anything here.

Open-Source Works

iKalibr: unified targetless spatiotemporal calibration for resilient integrated inertial systems.
River: a continuous-time-based radar-inertial velocity estimator.
eKalibr: an event-based visual intrinsic and spatiotemporal calibrator.

Research Works

eKalibr: an event-based visual calibrator. Related paper(s) 👇:
- S. Chen, X. Li*, L. Yuan and Z. Liu, "eKalibr: Dynamic Intrinsic Calibration for Event Cameras From First Principles of Events," in IEEE Robotics and Automation Letters (RA-L), 2025. [paper-ral] [paper-arXiv] [video] [code]
- S. Chen, X. Li*, and L. Yuan, "eKalibr-Stereo: Continuous-Time Spatiotemporal Calibration for Event-Based Stereo Visual Systems," in IEEE Robotics and Automation Letters (RA-L), 2025. [paper-ral] [paper-arXiv] [video] [code]
- S. Chen, X. Li*, and L. Yuan. eKalibr-Inertial: Continuous-Time Spatiotemporal Calibration for Event-Based Visual-Inertial Systems[J]. arXiv preprint arXiv:2509.05923, 2025. [paper-arXiv] [code]
iKalibr: a continuous-time, targetless, unified spatiotemporal calibrator. Related paper(s) 👇:
- S. Chen, X. Li*, S. Li*, Y. Zhou, and X. Yang, "iKalibr: Unified Targetless Spatiotemporal Calibration for Resilient Integrated Inertial Systems," in IEEE Transactions on Robotics (T-RO), 2025. [paper-tro] [paper-arXiv] [video 1] [video 2] [code]
- S. Chen, X. Li*, S. Li and Y. Zhou, "iKalibr-RGBD: Partially-Specialized Target-Free Visual-Inertial Spatiotemporal Calibration For RGBDs via Continuous-Time Velocity Estimation," in IEEE Robotics and Automation Letters (RA-L), 2024. [paper-ral] [paper-arXiv] [code]
- S. Chen, X. Li*, S. Li, Y. Zhou and S. Wang, "MI-Calib: An Open-Source Spatiotemporal Calibrator for Multiple IMUs Based on Continuous-Time Batch Optimization," in IEEE Robotics and Automation Letters (RA-L), 2024. [paper-ral] [code] [video]
- S. Chen, X. Li*, S. Li, Y. Zhou and S. Wang, "RIs-Calib: An Open-Source Spatiotemporal Calibrator for Multiple 3D Radars and IMUs Based on Continuous-Time Estimation," in IEEE Transactions on Instrumentation and Measurement (TIM), 2024. [paper-tim] [paper-arXiv] [code] [video]
- S. Chen, X. Li*, S. Li, Y. Zhou and S. Wang, "Targetless Spatiotemporal Calibration for Multiple Heterogeneous Cameras And IMUs Based on Continuous-Time Trajectory Estimation," in IEEE Transactions on Instrumentation and Measurement (TIM), 2023. [paper-tim]

River: a continuous-time-based radar-inertial velocity estimator. Related paper(s) 👇:
- S. Chen, X. Li*, S. Li, Y. Zhou and S. Wang, "River: A Tightly-Coupled Radar-Inertial Velocity Estimator Based on Continuous-Time Optimization," in IEEE Robotics and Automation Letters (RA-L), 2024. [paper-ral] [code] [video]

Interesting Point

So why is my nickname ULong2 😃? ULong is a data type in C++ that stands for unsigned long integer, which can store a large number, but no negative numbers are allowed. This represents my desire to explore a wide range of knowledge and a positive (non-negative) mindset. Interestingly, Long is also the pinyin for one of the Chinese characters in my name. And the number 2, yes, is my lucky number.