Deploying Vision-Language-Action (VLA) models in real robotic systems requires robustness not only to semantic and perceptual variations, but also to embodiment-side faults that change how actions are physically realized. Real robots can experience joint-level changes caused by actuator degradation, hardware faults, safety limits, collision damage, or wear-induced friction. These faults are critical because they alter the action-to-motion interface of a policy, disrupting the learned closed-loop relationship between commanded actions, realized motion, and subsequent observations. In this work, we study realistic joint-level physical faults and show that VLA models are vulnerable when predicted actions are executed through a perturbed robot body. Our analysis reveals joint-dependent effects, with heterogeneous degradation in task success across affected joints. We also show that performance drops cannot be attributed solely to physical infeasibility, since feasible faults such as increased joint friction can still substantially reduce success rates and induce closed-loop execution mismatch. Motivated by these findings, we propose Joint-level Physical-fault Aware Residual Calibrator (J-PARC), a lightweight residual calibration framework built on top of a frozen VLA policy. J-PARC infers a latent joint-fault regime from recent joint dynamics and conditions a shared residual calibrator on this regime, enabling adaptive action correction across faulty joints. Experiments show that J-PARC improves robustness under joint-level faults while preserving fault-free environment performance.

翻译：将视觉-语言-动作（VLA）模型部署于真实机器人系统时，不仅需要应对语义和感知变化，还必须具备对改变动作物理实现方式的具身侧故障的鲁棒性。真实机器人可能因执行器退化、硬件故障、安全限制、碰撞损伤或磨损引起的摩擦而经历关节级变化。这些故障至关重要，因为它们改变了策略的动作-运动接口，破坏了指令动作、实际运动及后续观测之间已学习的闭环关系。本研究通过分析真实关节级物理故障，揭示了当预测动作通过受扰动机器人实体执行时VLA模型的脆弱性。我们的分析发现了关节依赖效应，受影响的关节在任务成功率上呈现异质性退化。同时表明，性能下降不能单纯归因于物理不可行性——例如关节摩擦增大这类可行故障仍会显著降低成功率，并引发闭环执行失配。基于这些发现，我们提出了关节级物理故障感知残差校准器（J-PARC），该轻量级残差校准框架建立在冻结VLA策略之上。J-PARC从近期关节动态中推断潜在关节故障模式，并据此调控共享残差校准器，从而实现跨故障关节的适应性动作修正。实验表明，J-PARC在保持无故障环境性能的同时，提升了关节级故障下的鲁棒性。