MolmoAct: Action Reasoning Models that can Reason in Space

Fuente: arXiv
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Main Authors: Lee, Jason, Duan, Jiafei, Fang, Haoquan, Deng, Yuquan, Liu, Shuo, Li, Boyang, Fang, Bohan, Zhang, Jieyu, Wang, Yi Ru, Lee, Sangho, Han, Winson, Pumacay, Wilbert, Wu, Angelica, Hendrix, Rose, Farley, Karen, VanderBilt, Eli, Farhadi, Ali, Fox, Dieter, Krishna, Ranjay
Format: Preprint
Published: 2025
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author Lee, Jason
Duan, Jiafei
Fang, Haoquan
Deng, Yuquan
Liu, Shuo
Li, Boyang
Fang, Bohan
Zhang, Jieyu
Wang, Yi Ru
Lee, Sangho
Han, Winson
Pumacay, Wilbert
Wu, Angelica
Hendrix, Rose
Farley, Karen
VanderBilt, Eli
Farhadi, Ali
Fox, Dieter
Krishna, Ranjay
author_facet Lee, Jason
Duan, Jiafei
Fang, Haoquan
Deng, Yuquan
Liu, Shuo
Li, Boyang
Fang, Bohan
Zhang, Jieyu
Wang, Yi Ru
Lee, Sangho
Han, Winson
Pumacay, Wilbert
Wu, Angelica
Hendrix, Rose
Farley, Karen
VanderBilt, Eli
Farhadi, Ali
Fox, Dieter
Krishna, Ranjay
contents Reasoning is central to purposeful action, yet most robotic foundation models map perception and instructions directly to control, which limits adaptability, generalization, and semantic grounding. We introduce Action Reasoning Models (ARMs), a class of robotic foundation models that integrate perception, planning, and control through a structured three-stage pipeline. Our model, MolmoAct, encodes observations and instructions into depth-aware perception tokens, generates mid-level spatial plans as editable trajectory traces, and predicts precise low-level actions, enabling explainable and steerable behavior. MolmoAct-7B-D achieves strong performance across simulation and real-world settings: 70.5% zero-shot accuracy on SimplerEnv Visual Matching tasks, surpassing closed-source Pi-0 and GR00T N1.5; 86.6% average success on LIBERO, including an additional 6.3% gain over ThinkAct on long-horizon tasks; and in real-world fine-tuning, an additional 10% (single-arm) and an additional 22.7% (bimanual) task progression over Pi-0-FAST. It also outperforms baselines by an additional 23.3% on out-of-distribution generalization and achieves top human-preference scores for open-ended instruction following and trajectory steering. Furthermore, we release, for the first time, the MolmoAct Dataset -- a mid-training robot dataset comprising over 10,000 high quality robot trajectories across diverse scenarios and tasks. Training with this dataset yields an average 5.5% improvement in general performance over the base model. We release all model weights, training code, our collected dataset, and our action reasoning dataset, establishing MolmoAct as both a state-of-the-art robotics foundation model and an open blueprint for building ARMs that transform perception into purposeful action through structured reasoning. Blogpost: https://allenai.org/blog/molmoact
format Preprint
id arxiv_https___arxiv_org_abs_2508_07917
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MolmoAct: Action Reasoning Models that can Reason in Space
Lee, Jason
Duan, Jiafei
Fang, Haoquan
Deng, Yuquan
Liu, Shuo
Li, Boyang
Fang, Bohan
Zhang, Jieyu
Wang, Yi Ru
Lee, Sangho
Han, Winson
Pumacay, Wilbert
Wu, Angelica
Hendrix, Rose
Farley, Karen
VanderBilt, Eli
Farhadi, Ali
Fox, Dieter
Krishna, Ranjay
Robotics
Reasoning is central to purposeful action, yet most robotic foundation models map perception and instructions directly to control, which limits adaptability, generalization, and semantic grounding. We introduce Action Reasoning Models (ARMs), a class of robotic foundation models that integrate perception, planning, and control through a structured three-stage pipeline. Our model, MolmoAct, encodes observations and instructions into depth-aware perception tokens, generates mid-level spatial plans as editable trajectory traces, and predicts precise low-level actions, enabling explainable and steerable behavior. MolmoAct-7B-D achieves strong performance across simulation and real-world settings: 70.5% zero-shot accuracy on SimplerEnv Visual Matching tasks, surpassing closed-source Pi-0 and GR00T N1.5; 86.6% average success on LIBERO, including an additional 6.3% gain over ThinkAct on long-horizon tasks; and in real-world fine-tuning, an additional 10% (single-arm) and an additional 22.7% (bimanual) task progression over Pi-0-FAST. It also outperforms baselines by an additional 23.3% on out-of-distribution generalization and achieves top human-preference scores for open-ended instruction following and trajectory steering. Furthermore, we release, for the first time, the MolmoAct Dataset -- a mid-training robot dataset comprising over 10,000 high quality robot trajectories across diverse scenarios and tasks. Training with this dataset yields an average 5.5% improvement in general performance over the base model. We release all model weights, training code, our collected dataset, and our action reasoning dataset, establishing MolmoAct as both a state-of-the-art robotics foundation model and an open blueprint for building ARMs that transform perception into purposeful action through structured reasoning. Blogpost: https://allenai.org/blog/molmoact
title MolmoAct: Action Reasoning Models that can Reason in Space
topic Robotics
url https://arxiv.org/abs/2508.07917