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NeMo-map: Neural implicit flow fields for spatio-temporal motion mapping
Örebro University, School of Science and Technology.ORCID iD: 0000-0002-1298-5607
Örebro University, School of Science and Technology.ORCID iD: 0000-0002-4245-6706
Technical University of Munich, Germany.
Aalto University, Finland.
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2026 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Safe and efficient robot operation in complex human environments can benefit from good models of site-specific motion patterns. Maps of Dynamics (MoDs) provide such models by encoding statistical motion patterns in a map, but existing representations use discrete spatial sampling and typically require costly offline construction. We propose a continuous spatio-temporal MoD representation based on implicit neural functions that directly map coordinates to the parameters of a Semi-Wrapped Gaussian Mixture Model. This removes the need for discretization and imputation for unevenly sampled regions, enabling smooth generalization across both space and time. Evaluated on two public datasets with real-world people tracking data, our method achieves better accuracy of motion representation and smoother velocity distributions in sparse regions while still being computationally efficient, compared to available baselines. The proposed approach demonstrates a powerful and efficient way of modeling complex human motion patterns and high performance in the trajectory prediction downstream task.

Place, publisher, year, edition, pages
2026.
National Category
Computer Sciences
Identifiers
URN: urn:nbn:se:oru:diva-131377OAI: oai:DiVA.org:oru-131377DiVA, id: diva2:2101912
Conference
The Fourteenth International Conference on Learning Representations (ICLR 2026), Rio de Janeiro, Brazil, April 23-27, 2026
Available from: 2026-09-16 Created: 2026-09-16 Last updated: 2026-09-16Bibliographically approved
In thesis
1. Spatio-Temporal Representations of Human Dynamics for Motion Prediction and Robot Navigation
Open this publication in new window or tab >>Spatio-Temporal Representations of Human Dynamics for Motion Prediction and Robot Navigation
2026 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Safe and efficient robot operation in human-shared environments requires understanding and anticipating how people move. This thesis advances the representation, learning, and exploitation of spatio-temporal Maps of Dynamics (MoDs), which are structured models that encode statistical motion patterns observed in an environment, for long-horizon human motion prediction and human-aware robot navigation.

On the representation side, this thesis addresses key limitations of existing MoDs along four complementary dimensions: adaptivity, continuity, robustness, and context-awareness. First, for adaptivity, an online learning method based on stochastic Expectation Maximization enables MoDs to adapt incrementally to changing motion patterns without costly offline reconstruction, maintaining accuracy at substantially lower computational cost and enablin glong-term deployment on mobile robots without storing historical data. Second, for continuity, a neural implicit representation eliminates spatial discretization by learning a continuous function that maps arbitrary spatio-temporal coordinates to multi-modal velocity distributions, achieving higher representation accuracy than grid-based approaches while training efficiently. Third, for robustness, a method inspired by data-driven airflow modeling extracts the structured laminar component from observed motion, mitigating the impact of anomalous data and producing more robust motion pattern representations. Fourth, for context-awareness, conditioning MoDs on time of day and agent class captures heterogeneous motion behaviours that single aggregated maps cannot represent, yielding more informative motion priors that directly improve downstream prediction accuracy.

On the exploitation side, MoDs are shown to serve as powerful environmentlevel priors for downstream tasks. This thesis exploits MoDs first f or longhorizon human motion prediction, where a sampling-based framework queries MoDs at each prediction step to generate multi-modal, spatially grounded trajectories that respect the environment topology over horizons of up to 60 seconds. The predicted trajectories implicitly follow corridors, turn at junctions, and reach semantically meaningful goal regions, improving interpretability. Across multiple datasets and prediction horizons, MoD-based methods outperform learning-based and diffusion-based baselines at long horizons, with the advantage being most pronounced under data scarcity and class imbalance. This framework is further extended with laminar enhancement, temporal conditioning, and agent-class conditioning, along with a trajectory ranking mechanism based on cumulative MoD likelihood that provides a principled way to select the most probable prediction from the multi-modal output, improving practical utility for real-world deployment.

This thesis also exploits MoDs for human-aware robot navigation. A hierarchical framework that treats crowd motion as guidance rather than solely as an obstacle enables proactive flow alignment in dense crowds, addressing the freezing robot problem and successfully transferring from simulation to real-world deployment in a public museum without retraining. Finally, MoD priors are integrated into multi-agent path finding to reduce conflicts between robots and human flows in shared environments, extending the utility of structured motion representations from single-robot planning to multi-robot coordination.

Together, these contributions demonstrate that learned structured representations of human dynamics provide a unifying foundation for prediction and navigation, extending the robot’s contextual awareness beyond its immediate sensing range toward more predictive, socially aware, and robust autonomous operation in human-shared spaces.

Place, publisher, year, edition, pages
Örebro: Örebro University, 2026. p. 62
Series
Örebro Studies in Technology, ISSN 1650-8580 ; 117
Keywords
Spatiotemporal Pattern Learning, Neural Implicit Representations, Generative Modeling, Maps of Dynamics, Human Motion Prediction
National Category
Computer Sciences
Identifiers
urn:nbn:se:oru:diva-130800 (URN)9789175297996 (ISBN)
Public defence
2026-10-12, Örebro universitet, Långhuset, Hörsal L3, Fakultetsgatan 1, Örebro, 13:15 (English)
Opponent
Supervisors
Available from: 2026-08-25 Created: 2026-08-25 Last updated: 2026-09-23Bibliographically approved

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Zhu, YufeiShih-Min, YangLilienthal, Achim J.Magnusson, Martin

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Citation style
  • apa
  • ieee
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