让视觉语言动作模型实时纠错,动态调整执行长度。
VLA-Corrector: Lightweight Detect-and-Correct Inference for Adaptive Action Horizon

- 用轻量级视觉监控器检测视觉特征偏差,触发纠错
- 偏差持续时中断旧动作,用梯度引导重规划新动作
- 无需重训练模型,适合高接触力的长期机械臂任务
视觉-语言-动作(VLA)基础模型在具身智能中取得显著进展。为降低策略调用频率并保持时间连贯性,多数生成式策略采用固定动作时长的批量执行机制,但此“预测后盲目执行”范式牺牲了闭环反应能力:在高接触场景中,微小扰动会迅速在开环盲区放大,导致误差累积并最终任务失败。为此,我们提出VLA-Corrector,一种无需修改主干策略权重的轻量级检测-纠正推理框架。该框架引入一个轻量级潜在空间视觉监控器(LVM),持续比对预测与实际视觉特征演化,实现对视觉动态偏差的在线检测。一旦检测到持续偏差,系统触发截断事件,丢弃剩余过时动作,并通过在线梯度引导(OGG)进行纠正重规划。该检测-纠正机制自然形成事件触发的自适应动作时长:当当前批次仍可靠时维持长时执行,执行开始漂移时则启动短时重规划。此举缓解了静态时长带来的执行鲁棒性与策略调用频率之间的权衡。VLA-Corrector可无缝集成至不同VLA模型,无需额外训练,在保留动作批量化效率的同时显著提升长期、高接触任务中的鲁棒性。
原文摘要 · Abstract (English)
Vision-Language-Action (VLA) foundation models have recently achieved strong progress in embodied intelligence. To reduce policy-call frequency while preserving temporal coherence, most generative policies adopt an action chunk mechanism, executing multiple future actions in an open-loop manner under a fixed action horizon. However, this "predict-then-blindly-execute" paradigm sacrifices closed-loop reactivity: in contact-rich physical interactions, even small local perturbations can rapidly amplify within the open-loop blind spot, leading to compounding errors and ultimately task failure. To address this limitation, we propose VLA-Corrector, a lightweight corrective inference framework for action-chunked VLA policies. Without modifying the backbone policy weights, VLA-Corrector introduces a lightweight Latent-space Vision Monitor (LVM) that continuously compares predicted and actual visual feature evolution, enabling online detection of visual dynamics deviations. Once persistent deviation is detected, the system triggers a truncation event, discards the remaining stale actions, and invokes corrective replanning via Online Gradient Guidance (OGG). The detect-and-correct mechanism of VLA-Corrector naturally induces an event-triggered adaptive action horizon: it preserves long-horizon execution when the current chunk remains reliable, and invokes short-horizon corrective replanning when execution begins to drift. In doing so, VLA-Corrector mitigates the trade-off imposed by static horizons between execution robustness and policy-call frequency. It can be integrated into different VLA models without further retraining the VLA backbone, interrupting compounding errors while preserving much of the efficiency benefit of action chunking and substantially improving robustness in long-horizon, contact-rich robotic manipulation tasks.
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