VLAW: Iterative Co-Improvement of Vision-Language-Action Policy and World Model

Fuente: arXiv
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Auteurs principaux: Guo, Yanjiang, Lee, Tony, Shi, Lucy Xiaoyang, Chen, Jianyu, Liang, Percy, Finn, Chelsea
Format: Preprint
Publié: 2026
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author Guo, Yanjiang
Lee, Tony
Shi, Lucy Xiaoyang
Chen, Jianyu
Liang, Percy
Finn, Chelsea
author_facet Guo, Yanjiang
Lee, Tony
Shi, Lucy Xiaoyang
Chen, Jianyu
Liang, Percy
Finn, Chelsea
contents The goal of this paper is to improve the performance and reliability of vision-language-action (VLA) models through iterative online interaction. Since collecting policy rollouts in the real world is expensive, we investigate whether a learned simulator-specifically, an action-conditioned video generation model-can be used to generate additional rollout data. Unfortunately, existing world models lack the physical fidelity necessary for policy improvement: they are predominantly trained on demonstration datasets that lack coverage of many different physical interactions (particularly failure cases) and struggle to accurately model small yet critical physical details in contact-rich object manipulation. We propose a simple iterative improvement algorithm that uses real-world roll-out data to improve the fidelity of the world model, which can then, in turn, be used to generate supplemental synthetic data for improving the VLA model. In our experiments on a real robot, we use this approach to improve the performance of a state-of-the-art VLA model on multiple downstream tasks. We achieve a 39.2% absolute success rate improvement over the base policy and 11.6% improvement from training with the generated synthetic rollouts. Videos can be found at this anonymous website: https://sites.google.com/view/vla-w
format Preprint
id arxiv_https___arxiv_org_abs_2602_12063
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle VLAW: Iterative Co-Improvement of Vision-Language-Action Policy and World Model
Guo, Yanjiang
Lee, Tony
Shi, Lucy Xiaoyang
Chen, Jianyu
Liang, Percy
Finn, Chelsea
Robotics
The goal of this paper is to improve the performance and reliability of vision-language-action (VLA) models through iterative online interaction. Since collecting policy rollouts in the real world is expensive, we investigate whether a learned simulator-specifically, an action-conditioned video generation model-can be used to generate additional rollout data. Unfortunately, existing world models lack the physical fidelity necessary for policy improvement: they are predominantly trained on demonstration datasets that lack coverage of many different physical interactions (particularly failure cases) and struggle to accurately model small yet critical physical details in contact-rich object manipulation. We propose a simple iterative improvement algorithm that uses real-world roll-out data to improve the fidelity of the world model, which can then, in turn, be used to generate supplemental synthetic data for improving the VLA model. In our experiments on a real robot, we use this approach to improve the performance of a state-of-the-art VLA model on multiple downstream tasks. We achieve a 39.2% absolute success rate improvement over the base policy and 11.6% improvement from training with the generated synthetic rollouts. Videos can be found at this anonymous website: https://sites.google.com/view/vla-w
title VLAW: Iterative Co-Improvement of Vision-Language-Action Policy and World Model
topic Robotics
url https://arxiv.org/abs/2602.12063