Jiaheng Sun | Northeastern University, China

About Me

I am an undergraduate student at the School of Computer Science and Engineering, Northeastern University, China, expecting my B.Eng. in June 2027. I am currently a visiting student researcher at the Department of Informatics, University of Oslo, hosted by Prof. Tor Skeie within the DSTrain project. At Northeastern I work with Prof. Tiancheng Zhang and Asst. Prof. Hengyu Liu (Aalborg University).

Research Interests

My research connects spatio-temporal data systems with foundation models in two ways.

Foundation models as supervision. Diffusion-based trajectory predictors are sensitive to their initial noise prior, but a vision-language critic returns a non-differentiable scalar, so there is no gradient path from its judgment into the noise space. I use reinforcement learning to turn scalar VLM rewards into scene-conditioned refinements of that prior, with the critic invoked only during training and bypassed at inference.
Measuring what foundation models actually do. Benchmarks for LLM data agents report aggregate task accuracy, which cannot say which capability an agent is missing, and on trajectory data many tasks are passable by tabular shortcuts that never reason spatially. I build diagnostic benchmarks that decompose a run into capability milestones, probe for shortcuts, and refuse to draw conclusions from saturated tasks.

Keywords: trajectory prediction and planning for autonomous driving · diffusion models · reinforcement learning · VLM/LLM agents · benchmark design and evaluation.

News

[Aug. 2026] Visiting the Department of Informatics, University of Oslo, hosted by Prof. Tor Skeie (DSTrain project on LLM-based trajectory planning for autonomous driving).
[2026] VLM-Guided Diffusion Models for Vehicle Trajectory Prediction is under major revision at World Wide Web Journal.
[Sep. 2025] First Prize (Liaoning Province), National Undergraduate Mathematical Contest in Modeling.

Publications

VLM-Guided Diffusion Models for Vehicle Trajectory Prediction

Jiaheng Sun*, Hengyu Liu*, Zhihong Cui, Haoyu Wang, Xinyuan Zhang, Amir Taherkordi, Tor Skeie, Jianwei Zhang, Kaize Shi, Tiancheng Zhang (*Equal contribution)

World Wide Web Journal (WWWJ), 2026. CCF B.

Co-first author · Under review (major revision)

TripWire: A Capability-Diagnostic Benchmark for Spatio-Temporal Data Agents

Jiaheng Sun, Hengyu Liu, Zhihong Cui, Tiancheng Zhang, et al.

Working title. In preparation, targeting ICLR 2027.

Benchmark and scoring design · evaluation harness

Patents

A Trajectory Prediction Method for Autonomous Driving Based on VLM, PPO and Diffusion Models. Tiancheng Zhang, Jiaheng Sun (second inventor), Hengyu Liu, Haoyu Wang, Huimin Zhu, Mengxin Wang. Chinese Invention Patent, filed and under examination.

Education and Awards

B.Eng. in Computer Science, Northeastern University, China. Sep. 2023 – Jun. 2027 (expected). GPA 4.159/5.000, rank 17/214 (top 7.98%).
Visiting Student Researcher, Department of Informatics, University of Oslo, Norway. Aug. 2026.
First Prize (Liaoning Province), National Undergraduate Mathematical Contest in Modeling, 2025.
University Scholarship (Third Class), Northeastern University, 2024 and 2025.
English: IELTS Academic 7.0 · College English Test Band 6: 547/710.