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Main Authors: Zhang, Zhilong, Ren, Haoxiang, Sun, Yihao, Sheng, Yifei, Wang, Haonan, Lin, Haoxin, Wu, Zhichao, Bacon, Pierre-Luc, Yu, Yang
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2603.20607
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author Zhang, Zhilong
Ren, Haoxiang
Sun, Yihao
Sheng, Yifei
Wang, Haonan
Lin, Haoxin
Wu, Zhichao
Bacon, Pierre-Luc
Yu, Yang
author_facet Zhang, Zhilong
Ren, Haoxiang
Sun, Yihao
Sheng, Yifei
Wang, Haonan
Lin, Haoxin
Wu, Zhichao
Bacon, Pierre-Luc
Yu, Yang
contents Vision-Language-Action (VLA) models show strong generalization for robotic control, but finetuning them with reinforcement learning (RL) is constrained by the high cost and safety risks of real-world interaction. Training VLA models in interactive world models avoids these issues but introduces several challenges, including pixel-level world modeling, multi-view consistency, and compounding errors under sparse rewards. Building on recent advances across large multimodal models and model-based RL, we propose VLA-MBPO, a practical framework to tackle these problems in VLA finetuning. Our approach has three key design choices: (i) adapting unified multimodal models (UMMs) for data-efficient world modeling; (ii) an interleaved view decoding mechanism to enforce multi-view consistency; and (iii) chunk-level branched rollout to mitigate error compounding. Theoretical analysis and experiments across simulation and real-world tasks demonstrate that VLA-MBPO significantly improves policy performance and sample efficiency, underscoring its robustness and scalability for real-world robotic deployment.
format Preprint
id arxiv_https___arxiv_org_abs_2603_20607
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Towards Practical World Model-based Reinforcement Learning for Vision-Language-Action Models
Zhang, Zhilong
Ren, Haoxiang
Sun, Yihao
Sheng, Yifei
Wang, Haonan
Lin, Haoxin
Wu, Zhichao
Bacon, Pierre-Luc
Yu, Yang
Robotics
Machine Learning
Vision-Language-Action (VLA) models show strong generalization for robotic control, but finetuning them with reinforcement learning (RL) is constrained by the high cost and safety risks of real-world interaction. Training VLA models in interactive world models avoids these issues but introduces several challenges, including pixel-level world modeling, multi-view consistency, and compounding errors under sparse rewards. Building on recent advances across large multimodal models and model-based RL, we propose VLA-MBPO, a practical framework to tackle these problems in VLA finetuning. Our approach has three key design choices: (i) adapting unified multimodal models (UMMs) for data-efficient world modeling; (ii) an interleaved view decoding mechanism to enforce multi-view consistency; and (iii) chunk-level branched rollout to mitigate error compounding. Theoretical analysis and experiments across simulation and real-world tasks demonstrate that VLA-MBPO significantly improves policy performance and sample efficiency, underscoring its robustness and scalability for real-world robotic deployment.
title Towards Practical World Model-based Reinforcement Learning for Vision-Language-Action Models
topic Robotics
Machine Learning
url https://arxiv.org/abs/2603.20607