UniPhys: Unified Planner and Controller with Diffusion for Flexible Physics-Based Character Control

Fuente: arXiv
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Autori principali: Wu, Yan, Karunratanakul, Korrawe, Luo, Zhengyi, Tang, Siyu
Natura: Preprint
Pubblicazione: 2025
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author Wu, Yan
Karunratanakul, Korrawe
Luo, Zhengyi
Tang, Siyu
author_facet Wu, Yan
Karunratanakul, Korrawe
Luo, Zhengyi
Tang, Siyu
contents Generating natural and physically plausible character motion remains challenging, particularly for long-horizon control with diverse guidance signals. While prior work combines high-level diffusion-based motion planners with low-level physics controllers, these systems suffer from domain gaps that degrade motion quality and require task-specific fine-tuning. To tackle this problem, we introduce UniPhys, a diffusion-based behavior cloning framework that unifies motion planning and control into a single model. UniPhys enables flexible, expressive character motion conditioned on multi-modal inputs such as text, trajectories, and goals. To address accumulated prediction errors over long sequences, UniPhys is trained with the Diffusion Forcing paradigm, learning to denoise noisy motion histories and handle discrepancies introduced by the physics simulator. This design allows UniPhys to robustly generate physically plausible, long-horizon motions. Through guided sampling, UniPhys generalizes to a wide range of control signals, including unseen ones, without requiring task-specific fine-tuning. Experiments show that UniPhys outperforms prior methods in motion naturalness, generalization, and robustness across diverse control tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2504_12540
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle UniPhys: Unified Planner and Controller with Diffusion for Flexible Physics-Based Character Control
Wu, Yan
Karunratanakul, Korrawe
Luo, Zhengyi
Tang, Siyu
Graphics
Computer Vision and Pattern Recognition
Robotics
Generating natural and physically plausible character motion remains challenging, particularly for long-horizon control with diverse guidance signals. While prior work combines high-level diffusion-based motion planners with low-level physics controllers, these systems suffer from domain gaps that degrade motion quality and require task-specific fine-tuning. To tackle this problem, we introduce UniPhys, a diffusion-based behavior cloning framework that unifies motion planning and control into a single model. UniPhys enables flexible, expressive character motion conditioned on multi-modal inputs such as text, trajectories, and goals. To address accumulated prediction errors over long sequences, UniPhys is trained with the Diffusion Forcing paradigm, learning to denoise noisy motion histories and handle discrepancies introduced by the physics simulator. This design allows UniPhys to robustly generate physically plausible, long-horizon motions. Through guided sampling, UniPhys generalizes to a wide range of control signals, including unseen ones, without requiring task-specific fine-tuning. Experiments show that UniPhys outperforms prior methods in motion naturalness, generalization, and robustness across diverse control tasks.
title UniPhys: Unified Planner and Controller with Diffusion for Flexible Physics-Based Character Control
topic Graphics
Computer Vision and Pattern Recognition
Robotics
url https://arxiv.org/abs/2504.12540