用在线强化学习提升视觉语言动作模型,让机器人在新场景下更聪明。
VLA-RL: Towards Masterful and General Robotic Manipulation with Scalable Reinforcement Learning

- 将机器人操作视为多轮对话,用强化学习优化预训练模型。
- 在LIBERO数据集上比最强基线提升4.5%,接近商用模型性能。
- 适合研究机器人泛化与推理缩放的学者,尤其关注测试时优化。
近期高容量视觉-语言-动作(VLA)模型通过模仿人类示范,在多种机器人操作任务中表现优异。然而,仅依赖有限状态的离线数据会导致分布外场景执行失败。我们提出VLA-RL,一个算法与系统框架,利用在线强化学习(RL)改进预训练的自回归VLA模型。统一视角下,我们引入轨迹级强化学习公式,将通用机器人操作轨迹建模为多模态多轮对话。为解决稀疏奖励问题,我们微调预训练视觉语言模型作为机器人过程奖励模型,使用自动提取任务片段上的伪奖励标签进行训练。为实现高效扩展,我们发现若干关键改进:课程选择策略、GPU均衡的向量化环境、批量解码和评论器预热。VLA-RL使OpenVLA-7B在LIBERO的40个挑战性任务中超越最强微调基线4.5%,甚至匹配先进商业模型π₀-FAST的性能。值得注意的是,我们观察到测试时优化的收益随增强而增长,暗示机器人领域存在早期的推理缩放规律。
原文摘要 · Abstract (English)
Recent high-capacity vision-language-action (VLA) models have demonstrated impressive performance on a range of robotic manipulation tasks by imitating human demonstrations. However, exploiting offline data with limited visited states will cause execution failure in out-of-distribution scenarios. Intuitively, an exploration-based method that improves on online collected data at test time could address this limitation. We present VLA-RL, an algorithmic and systematic framework that leverages online reinforcement learning (RL) to improve pretrained auto-regressive VLAs in downstream tasks. Within a unified perspective, we first introduce a trajectory-level RL formulation for auto-regressive VLA training, which models general robotic manipulation trajectory as multi-modal multi-turn conversation. To address the challenge of sparse rewards, we fine-tune a pretrained vision-language model as a robotic process reward model, which is trained on pseudo reward labels annotated on automatically extracted task segments. To scale up, we identify several implementation findings that improve the stability and efficiency including curriculum selection strategy, GPU-balanced vectorized environments, batch decoding, and critic warmup. VLA-RL enables OpenVLA-7B to surpass the strongest finetuned baseline by 4.5% on 40 challenging robotic manipulation tasks in LIBERO, and even matches the performance of advanced commercial models such as $π_0$-FAST. Notably, we observe that VLA-RL benefits from increased test-time optimization, indicating an early spark of inference scaling laws in robotics.
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