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arXiv · 2605.28736

Imitation Learning for Robot Assistance in Open Surgery: A Multi-Policy Evaluation on Suture Following

Xucheng Wang·Zhizhou Yang·Xiaoman Zhang·Sung Eun Kim·Romain Hardy·Pranav Rajpurkar
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Abstract

This study presents the first evaluation of general-purpose imitation learning for surgeon-robot collaborative assistance in open surgery, targeting suture following: the grab-pull-release motion an assistant performs at every stitch. We collect 160 teleoperated demonstrations (32,374 frames) on an open-source robot arm, benchmark four architecturally diverse imitation learning policies (ACT, Diffusion Policy, SmolVLA, $\pi_0$) across 28 trained models evaluated in 32 configurations along three clinically motivated dimensions: dataset size, camera viewpoint, and background variation. Our results demonstrate that under ideal conditions, the four policies achieve $50$-$75\%$ task success, with depth error as the dominant failure mode across all architectures. Among all policies, $\pi_0$ achieves the strongest results with a pretrained vision-language backbone, demonstrating superior data efficiency, greater robustness to background variation, and smoother trajectories compatible with surgical workflow. When deployed in a surgeon-robot suturing trial, $\pi_0$ yields a $92\%$ stitch completion rate. These findings establish collaborative robotic assistance in open surgery as a feasible target for imitation learning and highlight depth perception and end-effector design as key priorities for clinical translation.

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Xucheng Wang, Zhizhou Yang, Xiaoman Zhang, Sung Eun Kim, Romain Hardy, Pranav Rajpurkar. 2026-05-27. Imitation Learning for Robot Assistance in Open Surgery: A Multi-Policy Evaluation on Suture Following. https://arxiv.org/abs/2605.28736

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