Representing actions for robot hands is actually very challenging. Robot hands have different sizes and shapes, and different degrees of freedom. Representing their actions purely as joint states — as we naively would — leads to less transfer across the wide variety of available hands. Instead, could we design a universal hand action space to allow robots to learn cross-embodiment dexterous manipulation more easily?

Luis Felipe Casas and Yu Xiang come on to tell us about UHAS: the Unified Hand Action Space, a sphere-based action representation which enables cross-ebmodiment learning of dexterous manipulation skills.

Watch Episode #97 of RoboPapers, with Chris Paxton and Jiafei Duan, today to learn more!

Abstract

Robot manipulation policies are typically tied to specific robotic hand embodiments, limiting the transfer of learned behaviors across platforms with different kinematic structures. In this work, we propose the Unified Hand Action Space (UHAS), a sphere-based unified action representation for cross-embodiment dexterous manipulation. UHAS represents robotic hand actions as geometric deformations of a canonical sphere and uses a Cascade Inverse Kinematics (CIK) algorithm to map the shared representation to embodiment-specific joint configurations. Using reinforcement learning, we train dexterous manipulation policies directly in the proposed action space for in-hand cube reorientation tasks. We evaluate our method in both simulation and real-world experiments across multiple robotic hands, including the Allegro Hand, LEAP Hand, Shadow Hand, and MANO Human Hand. Experimental results demonstrate effective dexterous manipulation, zero-shot transfer to unseen hands, rapid finetuning across embodiments, and successful real-world deployment. Our experiments show that the proposed UHAS representation enables stable dexterous control and cross-embodiment policy transfer across robotic hands.

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ArXiV: https://arxiv.org/abs/2607.03570

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Ep#97: Cross-Embodiment Robot Manipulation via a Unified Hand Action Space

RoboPapers

Ep#97: Cross-Embodiment Robot Manipulation via a Unified Hand Action Space