Supervised Mixture-of-Experts for Surgical Grasping and Retraction

Fuente: arXiv
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Auteurs principaux: Mazza, Lorenzo, Rodriguez, Ariel, Younis, Rayan, Lelis, Martin, Hellig, Ortrun, Li, Chenpan, Bodenstedt, Sebastian, Wagner, Martin, Speidel, Stefanie
Format: Preprint
Publié: 2026
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author Mazza, Lorenzo
Rodriguez, Ariel
Younis, Rayan
Lelis, Martin
Hellig, Ortrun
Li, Chenpan
Bodenstedt, Sebastian
Wagner, Martin
Speidel, Stefanie
author_facet Mazza, Lorenzo
Rodriguez, Ariel
Younis, Rayan
Lelis, Martin
Hellig, Ortrun
Li, Chenpan
Bodenstedt, Sebastian
Wagner, Martin
Speidel, Stefanie
contents Imitation learning has achieved remarkable success in robotic manipulation, yet its application to surgical robotics remains challenging due to data scarcity, constrained workspaces, and the need for an exceptional level of safety and predictability. We present a supervised Mixture-of-Experts (MoE) architecture designed for phase-structured surgical manipulation tasks, which can be added on top of any autonomous policy. Unlike prior surgical robot learning approaches that rely on multi-camera setups or thousands of demonstrations, we show that a lightweight action decoder policy like Action Chunking Transformer (ACT) can learn complex, long-horizon manipulation from less than 150 demonstrations using solely stereo endoscopic images, when equipped with our architecture. We evaluate our approach on the collaborative surgical task of bowel grasping and retraction, where a robot assistant interprets visual cues from a human surgeon, executes targeted grasping on deformable tissue, and performs sustained retraction. Our results show that generalist Vision Language Action models fail to acquire the task entirely, even under standard in-distribution conditions. Furthermore, while standard ACT achieves moderate success in-distribution, adopting a supervised MoE architecture significantly boosts its performance, yielding higher success rates in-distribution and demonstrating superior robustness in out-of-distribution scenarios, including novel grasp locations, reduced illumination, and partial occlusions. Notably, it generalizes to unseen testing viewpoints and also transfers zero-shot to ex vivo porcine tissue without additional training, offering a promising pathway toward in vivo deployment. To support this statement, we present qualitative preliminary results of policy roll-outs during in vivo porcine surgery.
format Preprint
id arxiv_https___arxiv_org_abs_2601_21971
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Supervised Mixture-of-Experts for Surgical Grasping and Retraction
Mazza, Lorenzo
Rodriguez, Ariel
Younis, Rayan
Lelis, Martin
Hellig, Ortrun
Li, Chenpan
Bodenstedt, Sebastian
Wagner, Martin
Speidel, Stefanie
Robotics
Artificial Intelligence
Machine Learning
Imitation learning has achieved remarkable success in robotic manipulation, yet its application to surgical robotics remains challenging due to data scarcity, constrained workspaces, and the need for an exceptional level of safety and predictability. We present a supervised Mixture-of-Experts (MoE) architecture designed for phase-structured surgical manipulation tasks, which can be added on top of any autonomous policy. Unlike prior surgical robot learning approaches that rely on multi-camera setups or thousands of demonstrations, we show that a lightweight action decoder policy like Action Chunking Transformer (ACT) can learn complex, long-horizon manipulation from less than 150 demonstrations using solely stereo endoscopic images, when equipped with our architecture. We evaluate our approach on the collaborative surgical task of bowel grasping and retraction, where a robot assistant interprets visual cues from a human surgeon, executes targeted grasping on deformable tissue, and performs sustained retraction. Our results show that generalist Vision Language Action models fail to acquire the task entirely, even under standard in-distribution conditions. Furthermore, while standard ACT achieves moderate success in-distribution, adopting a supervised MoE architecture significantly boosts its performance, yielding higher success rates in-distribution and demonstrating superior robustness in out-of-distribution scenarios, including novel grasp locations, reduced illumination, and partial occlusions. Notably, it generalizes to unseen testing viewpoints and also transfers zero-shot to ex vivo porcine tissue without additional training, offering a promising pathway toward in vivo deployment. To support this statement, we present qualitative preliminary results of policy roll-outs during in vivo porcine surgery.
title Supervised Mixture-of-Experts for Surgical Grasping and Retraction
topic Robotics
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2601.21971