ByteWrist: A Parallel Robotic Wrist Enabling Flexible and
  Anthropomorphic Motion for Confined Spaces
Authors: name: Jiawen Tian, name: Liqun Huang, name: Zhongren Cui, name: Jingchao Qiao, name: Jiafeng Xu, name: Xiao Ma, name: Zeyu Ren

This paper introduces ByteWrist, a novel highly-flexible and anthropomorphic
parallel wrist for robotic manipulation. ByteWrist addresses the critical
limitations of existing serial and parallel wrists in narrow-space operations
through a compact three-stage parallel drive mechanism integrated with
arc-shaped end linkages. The design achieves precise RPY (Roll-Pitch-Yaw)
motion while maintaining exceptional compactness, making it particularly
suitable for complex unstructured environments such as home services, medical
assistance, and precision assembly. The key innovations include: (1) a nested
three-stage motor-driven linkages that minimize volume while enabling
independent multi-DOF control, (2) arc-shaped end linkages that optimize force
transmission and expand motion range, and (3) a central supporting ball
functioning as a spherical joint that enhances structural stiffness without
compromising flexibility. Meanwhile, we present comprehensive kinematic
modeling including forward / inverse kinematics and a numerical Jacobian
solution for precise control. Empirically, we observe ByteWrist demonstrates
strong performance in narrow-space maneuverability and dual-arm cooperative
manipulation tasks, outperforming Kinova-based systems. Results indicate
significant improvements in compactness, efficiency, and stiffness compared to
traditional designs, establishing ByteWrist as a promising solution for
next-generation robotic manipulation in constrained environments.