A Direct Rigid Transmission 2-DoF Wrist Extension for Tendon-Driven Hand

Abstract:Dexterous manipulation in confined spaces requires local control of hand orientation. Without a wrist, a dexterous hand must obtain this local orientation through coordinated motion of the robot arm, often involving several joints and a more complex end-effector path. We present CRAFT-Wrist, a concentric 2-DoF wrist extension that mounts between a robot arm and the CRAFT Hand without modifying the hand. Two XC430-T240BB-T servos drive sideways and front-back rotation through short rigid transmissions. Our initial hardware prototype actuates both axes under load, achieving a demonstrated workspace of $\pm20^{\circ}$ in radial--ulnar deviation (left--right) and a front-back range of $+80^{\circ}$ in flexion and $-18^{\circ}$ in extension. We characterize the resulting finger-motor loading across several wrist postures and demonstrate how the wrist supplies local orientation in grasping, nail hammering, and blackboard wiping. Demonstrations and assembly instructions are available at this https URL.

Robotics (cs.RO)

arXiv:2609.22681 [cs.RO]

(or arXiv:2609.22681v1 [cs.RO] for this version)

https://doi.org/10.48550/arXiv.2609.22681 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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