用世界令牌提升智能体策略,训练时建模场景变化,部署零延迟。
World Tokens: Enhancing Embodied Policies with Training-Time World Modeling

- 训练时用世界适配器将视觉语言特征转为固定世界令牌,联合优化未来视频去噪与动作预测。
- 在LIBERO和SIMPLER上性能领先,真实机器人任务成功率显著优于基线,推理延迟保持与传统VLA相当。
- 部署时移除视频模型分支,实现高效闭环控制,适合对实时性要求高的物理智能体应用。
视觉-语言-动作(VLA)模型是嵌入式策略的主流范式,擅长高效闭环控制,但未显式建模任务进行中物理场景的演化。新兴的世界-动作模型(WAMs)利用预训练视频世界模型捕捉时空演化,但保留未来生成或大体积视频骨干网络会显著增加推理开销。本文提出世界令牌(World Tokens),一种基于世界适配器的嵌入式策略架构,该适配器连接视觉语言理解、世界动态建模与动作生成。它在训练阶段使用世界建模增强动作策略,部署时仍保持高效。具体地,世界适配器将视觉语言模型(VLM)特征转化为一组固定的世界令牌,同时作为未来视频去噪器和动作专家的唯一视觉语言上下文。共享条件使未来视频去噪的梯度直接作用于动作预测表示,而专用路由机制防止策略绕过该表示。部署时,世界模型分支被移除,仅保留VLM、世界适配器和动作专家,无需在线视频模型推理。采用20亿参数骨干网络且无嵌入式动作预训练,该方法在LIBERO上表现极具竞争力,在SIMPLER上达到最优平均性能,真实机器人任务成功率显著优于对比基线,并以与VLA相当的延迟生成每个动作块。
原文摘要 · Abstract (English)
Vision-language-action (VLA) models are a widely adopted paradigm for embodied policies. They excel at efficient closed-loop control but do not explicitly model how physical scenes evolve as a task unfolds. Recently emerging world-action models (WAMs) leverage pretrained video world models to capture spatiotemporal evolution, yet retaining future generation or a large video backbone in the control loop substantially increases inference cost. We introduce World Tokens, an embodied policy architecture built around a World Adapter that bridges visual-language understanding, world-dynamics modeling, and action generation. It uses world modeling during training to enhance the action policy while preserving efficient deployment. Specifically, the World Adapter transforms VLM features into a fixed set of world tokens, which condition a jointly fine-tuned future-video denoiser and simultaneously serve as the action expert's sole visual-language context. This shared conditioning allows gradients from future-video denoising to directly shape the representation used for action prediction, while exclusive routing prevents the policy from bypassing that representation. At deployment, the world-model branch is removed, leaving only the VLM, World Adapter, and action expert, with no online video-model inference. With a 2B backbone and no embodied action pretraining, World Tokens is highly competitive on LIBERO, attains the best reported averages on SIMPLER, substantially improves real-world R1 Pro success over a matched action-only baseline, and generates each action chunk at VLA-level latency.
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