Light-WAM: Efficient World Action Models with State-Fusion Action Decoding

Hugging Face Daily Papers Papers

Summary

Light-WAM is a lightweight world action model for efficient robot manipulation that uses a compact video backbone and downsampled latent space for future-video supervision, achieving high performance with low inference latency.

World Action Models (WAMs) extend robot policy learning by incorporating future prediction as an additional training objective, encouraging the policy to encode task-relevant temporal structure in its representations. Current WAMs often rely on large-scale generative architectures that incur high training costs and inference latency, making them difficult to deploy as efficient closed-loop policies. We propose Light-WAM, a lightweight World Action Model for efficient robot manipulation. Specifically, it is built with a compact video backbone and performs future-video supervision in a downsampled latent space, reducing the cost of video co-training while retaining its benefits for representation learning. For action prediction, Light-WAM introduces the StateFusionActionExpert, which reads adapted states from multiple backbone layers, fuses them through learned-query pooling, and directly predicts action chunks in a single forward pass. This design provides an efficient interface between video backbone representations and robot actions, avoiding the need for heavy generative action experts. Experiments demonstrate that Light-WAM maintains strong performance on LIBERO and achieves usable multi-task performance on RoboTwin 2.0, while using only 0.44B trainable parameters. It also achieves 72.03ms inference latency with 4.1GiB peak GPU memory and improved training throughput.
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Source: https://huggingface.co/papers/2606.08242

Abstract

Light-WAM is a lightweight world action model for robot manipulation that uses a compact video backbone and downsampled latent space for efficient future-video supervision, combined with a StateFusionActionExpert for direct action prediction.

World Action Models(WAMs) extendrobot policy learningby incorporatingfuture predictionas an additional training objective, encouraging the policy to encode task-relevant temporal structure in its representations. Current WAMs often rely on large-scalegenerative architecturesthat incur high training costs andinference latency, making them difficult to deploy as efficient closed-loop policies. We propose Light-WAM, a lightweight World Action Model for efficient robot manipulation. Specifically, it is built with a compactvideo backboneand performs future-video supervision in adownsampled latent space, reducing the cost of video co-training while retaining its benefits for representation learning. For action prediction, Light-WAM introduces theStateFusionActionExpert, which reads adapted states from multiple backbone layers, fuses them throughlearned-query pooling, and directly predictsaction chunksin a single forward pass. This design provides an efficient interface betweenvideo backbonerepresentations and robot actions, avoiding the need for heavy generative action experts. Experiments demonstrate that Light-WAM maintains strong performance on LIBERO and achieves usable multi-task performance on RoboTwin 2.0, while using only 0.44B trainable parameters. It also achieves 72.03msinference latencywith 4.1GiB peak GPU memory and improvedtraining throughput.

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