Knowledge Insulating Vision-Language-Action Models: Train Fast, Run Fast, Generalize Better

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Auteurs principaux: Driess, Danny, Springenberg, Jost Tobias, Ichter, Brian, Yu, Lili, Li-Bell, Adrian, Pertsch, Karl, Ren, Allen Z., Walke, Homer, Vuong, Quan, Shi, Lucy Xiaoyang, Levine, Sergey
Format: Preprint
Publié: 2025
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author Driess, Danny
Springenberg, Jost Tobias
Ichter, Brian
Yu, Lili
Li-Bell, Adrian
Pertsch, Karl
Ren, Allen Z.
Walke, Homer
Vuong, Quan
Shi, Lucy Xiaoyang
Levine, Sergey
author_facet Driess, Danny
Springenberg, Jost Tobias
Ichter, Brian
Yu, Lili
Li-Bell, Adrian
Pertsch, Karl
Ren, Allen Z.
Walke, Homer
Vuong, Quan
Shi, Lucy Xiaoyang
Levine, Sergey
contents Vision-language-action (VLA) models provide a powerful approach to training control policies for physical systems, such as robots, by combining end-to-end learning with transfer of semantic knowledge from web-scale vision-language model (VLM) training. However, the constraints of real-time control are often at odds with the design of VLMs: the most powerful VLMs have tens or hundreds of billions of parameters, presenting an obstacle to real-time inference, and operate on discrete tokens rather than the continuous-valued outputs that are required for controlling robots. To address this challenge, recent VLA models have used specialized modules for efficient continuous control, such as action experts or continuous output heads, which typically require adding new untrained parameters to the pretrained VLM backbone. While these modules improve real-time and control capabilities, it remains an open question whether they preserve or degrade the semantic knowledge contained in the pretrained VLM, and what effect they have on the VLA training dynamics. In this paper, we study this question in the context of VLAs that include a continuous diffusion or flow matching action expert, showing that naively including such experts significantly harms both training speed and knowledge transfer. We provide an extensive analysis of various design choices, their impact on performance and knowledge transfer, and propose a technique for insulating the VLM backbone during VLA training that mitigates this issue. Videos are available at https://pi.website/research/knowledge_insulation.
format Preprint
id arxiv_https___arxiv_org_abs_2505_23705
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Knowledge Insulating Vision-Language-Action Models: Train Fast, Run Fast, Generalize Better
Driess, Danny
Springenberg, Jost Tobias
Ichter, Brian
Yu, Lili
Li-Bell, Adrian
Pertsch, Karl
Ren, Allen Z.
Walke, Homer
Vuong, Quan
Shi, Lucy Xiaoyang
Levine, Sergey
Machine Learning
Robotics
Vision-language-action (VLA) models provide a powerful approach to training control policies for physical systems, such as robots, by combining end-to-end learning with transfer of semantic knowledge from web-scale vision-language model (VLM) training. However, the constraints of real-time control are often at odds with the design of VLMs: the most powerful VLMs have tens or hundreds of billions of parameters, presenting an obstacle to real-time inference, and operate on discrete tokens rather than the continuous-valued outputs that are required for controlling robots. To address this challenge, recent VLA models have used specialized modules for efficient continuous control, such as action experts or continuous output heads, which typically require adding new untrained parameters to the pretrained VLM backbone. While these modules improve real-time and control capabilities, it remains an open question whether they preserve or degrade the semantic knowledge contained in the pretrained VLM, and what effect they have on the VLA training dynamics. In this paper, we study this question in the context of VLAs that include a continuous diffusion or flow matching action expert, showing that naively including such experts significantly harms both training speed and knowledge transfer. We provide an extensive analysis of various design choices, their impact on performance and knowledge transfer, and propose a technique for insulating the VLM backbone during VLA training that mitigates this issue. Videos are available at https://pi.website/research/knowledge_insulation.
title Knowledge Insulating Vision-Language-Action Models: Train Fast, Run Fast, Generalize Better
topic Machine Learning
Robotics
url https://arxiv.org/abs/2505.23705