AI & Computational Science

LayerRoute: Action-Conditioned Mixture-of-Layers Routing for Vision-Language-Action Policies

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RoboticsMixture of experts

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LayerRoute introduces a novel routing interface for Vision-Language-Action policies that dynamically selects and combines representations from different layers of pretrained vision-language models based on the specific action being computed. The system includes a Layer Mixture Router that adaptively accesses cached visual-semantic representations and an Action-State Reread mechanism that reuses earlier action computations. Testing on simulation benchmarks and real-world robot tasks showed performance improvements of up to 7.2% on complex manipulation tasks while adding minimal additional parameters (0.31-3.87%).


This approach could make robot control systems more efficient and adaptable by allowing them to flexibly access the most relevant visual and semantic information for each specific manipulation task, potentially improving performance of vision-language models in real-world robotic applications without requiring significant computational overhead.


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⚠️ Preprint – Noch nicht peer-reviewed

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Abstract: Vision-Language-Action (VLA) policies leverage pretrained vision-language models (VLMs) to guide action generation for robot control. VLMs provide hierarchical visual-semantic representations that evolve across layers, from local visual geometry to abstract, language-aligned semantics; different manipulation tasks may therefore require different mixtures of layer representations. Meanwhile, the action module maintains intermediate representations that evolve throughout action computation and may provide useful information for subsequent decisions. However, existing VLA interfaces offer limited flexibility in representation access: VLM information is exposed through fixed layer assignments for each action layer, while intermediate action states are only propagated implicitly through residual streams without explicit reuse. We introduce LayerRoute, an action-conditioned representation routing interface that enables adaptive access to VLM layers and action representations. The Layer Mixture Router dynamically forms mixtures of cached VLM representations, while Action-State Reread reuses earlier action representations. Across diverse simulation and real-world benchmarks, LayerRoute consistently improves StarVLA-$pi$ and $pi_{0.5}$, achieving up to 7.2 gains on LIBERO Long with only 0.31% / 3.87% additional parameters. Ablation studies validate the benefit of action-conditioned layer routing, while routing analyses reveal structured allocation patterns across action layers and task settings.

Source: LayerRoute: Action-Conditioned Mixture-of-Layers Routing for Vision-Language-Action Policies