✨ TL;DR
This paper proposes temporal-difference calibration for vision-language-action models in robotics, connecting uncertainty calibration to reinforcement learning by showing that minimizing a sequential Brier score recovers the value function. The method improves calibration of task-success confidence in sequential decision-making tasks.
Vision-language-action models for robotics need reliable uncertainty quantification to assess confidence in task success, but calibration in sequential settings remains largely unexplored. A key challenge is that confidence predictions are made throughout an episode while task success is only determined at the episode's end, creating a mismatch between when predictions are made and when outcomes are observed. Existing calibration methods don't adequately address this temporal structure in episodic tasks.
The authors formulate sequential calibration by extending the Brier score to episodic tasks. They prove that for binary outcomes, the risk minimizer of this sequential Brier score coincides with the VLA policy's value function. This theoretical connection enables using temporal-difference value estimation as a calibration mechanism. The approach leverages standard RL techniques to improve confidence calibration over time steps within episodes.
What the paper shows.
TD calibration improves performance on both simulated and real-robot data compared to state-of-the-art baselines. Notably, when calibrated using temporal-difference methods, the VLA's single-step action probabilities yield competitive uncertainty estimates, contradicting recent findings that suggested these probabilities were insufficient for uncertainty quantification under different calibration approaches.
The paper focuses on binary task outcomes in episodic settings, which may limit applicability to continuous or more complex outcome spaces. The empirical evaluation, while including real-robot experiments, appears limited in scope regarding the diversity of tasks and environments tested. The paper does not thoroughly discuss computational overhead of TD calibration or provide detailed ablation studies on key design choices in the sequential Brier score formulation.
✨ Generated by Claude · Apr 25, 2026 · Read the PDF for authoritative content.