TEMPO: 視覚-言語-行動モデルのための意味-行動分離型RLポストトレーニング
TEMPO: Semantic-Action Decoupled RL Post-Training for Vision-Language-Action Models
VLAモデルのRLポストトレーニングにおいて、視覚-言語バックボーンを凍結し、意味投影層と行動エキスパートを異なる頻度で更新する二段階学習を提案。CALVINベンチマークと実機タスクで既存手法を上回る性能を達成した。
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著者: Ziheng Liu, Quantao Yang
分類: cs.RO, cs.CV
原文アブストラクト
Vision-language-action (VLA) models are commonly adapted to downstream manipulation tasks via supervised fine-tuning (SFT) or online reinforcement learning (RL) post-training. SFT is prone to distribution mismatch, and existing RL approaches typically apply a single, uniform update strategy to all model components, ignoring their distinct functional roles. We propose TEMPO, a semantic-action decoupled, two-timescale RL post-training framework for VLA models. TEMPO freezes the pretrained vision-language backbone to preserve general semantic representations, and restricts adaptation to two components with dedicated RL optimization loops: the semantic projection layer and the low-level action expert. We update them at different rates--the semantic projection layer infrequently, to keep the latent action stable, and the action expert frequently, to rapidly incorporate control feedback from online interaction. This decoupling RL fine-tuning strategy prevents fast policy updates from destabilizing high-level semantic representations while still allowing the action expert to learn efficiently from online feedback. Experiments on the CALVIN benchmark and real-world manipulation tasks demonstrate that TEMPO consistently outperforms both pretrained state-of-the-art VLA models and the RL post-training baseline, while reaching and maintaining higher evaluation rewards on two real-world tasks.
