给视觉语言动作模型加物理约束,让机器人操作更稳更准。
PhysVLA: Towards Physically-Grounded VLA for Embodied Robotic Manipulation

- 运行时插入物理校正模块,不改原模型也能提升性能。
- 实测成功率最高提升17%,轨迹抖动减少10倍,真实机械臂效果超50%。
- 适合想用现成VLA模型但又怕出错的机器人研发者。
视觉-语言-动作(VLA)模型能将视觉输入和自然语言指令直接映射为机器人控制策略,但因主要依赖行为演示数据训练,未显式引入刚体动力学或接触约束等基本物理规律,存在关键的物理缺口。标准的时间平滑处理虽缓解了部分问题,却牺牲了轨迹质量并引入短期记忆无法解决的失败。为此,本文提出PhysVLA(物理-VLA),一个可即插即用、无需重训练或权重访问的推理阶段框架,每步控制开销低于1毫秒。该框架拦截预测动作,仅获取模拟器或系统状态,通过双层修正:(i) 基于相位的有限状态机,划分任务阶段(接近、抓取、运输、放置);(ii) 选择性欧拉-拉格朗日门控机制,仅在动力学检测到不一致时激活。在七个自由度的Franka Panda机械臂上,对OpenVLA、OpenVLA-OFT、Force-VLA和Generalist-VLA在LIBERO-Spatial上的评估显示,该框架实现最高17%的成功率提升和19%的稳定性增益,无任何任务退化;所有四个骨干模型的轨迹效率提升最高达15%;在Robosuite Lift跨模拟器测试中,轨迹抖动鲁棒性提升最高10倍。进一步在真实Agilex Piper机械臂上验证,无需重训练即可部署,拾放任务成功率最高提升50%,证明物理感知可作为通用、与骨干无关的运行时组件。
原文摘要 · Abstract (English)
Vision-Language-Action (VLA) models excel at mapping visual inputs and natural language instructions directly to robotic control policies. However, because they are trained primarily to fit behavioural demonstration data, they do not explicitly enforce fundamental physical principles such as rigid-body dynamics or contact constraints. This exposes a critical physics gap: standard temporal smoothing applied on top of single-step or chunked VLAs trades trajectory quality for added failures that short-term memory cannot resolve. To bridge this gap, we introduce PhysVLA (Physics-VLA), a plug-and-play, inference-time framework designed to wrap any frozen VLA backbone without retraining, fine-tuning, or weight access, with less than 1 ms of overhead per control step. PhysVLA intercepts the predicted control action, captures only the simulator or system state, and applies a dual-layered correction: (i) a phase-aware finite-state machine that structures discrete task segments (approach, grasp, transport, and place), and (ii) a selective Euler-Lagrange gate that activates only when a dynamics oracle detects kinodynamic inconsistency. Evaluated across OpenVLA, OpenVLA-OFT, Force-VLA, and Generalist-VLA on LIBERO-Spatial with a 7-DoF Franka Panda, the framework delivers absolute success rate increases of up to 17% and stability increases of up to 19% with no per-task regressions, improves trajectory efficiency by up to 15% across all four backbones, and shows up to a 10x improvement in trajectory jerk robustness on a Robosuite Lift cross-simulator sweep. We further validate the framework on a real Agilex Piper arm with a pick-and-place task, confirming that PhysVLA transfers to physical hardware without retraining, with success-rate improvements of up to 50%, establishing physical awareness as a composable, backbone-agnostic runtime module.
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