Design of a Novel Cable-Driven 3-DOF Series-Parallel Wrist Module for Humanoid Arms

In this paper, a 3-DOF series-parallel humanoid arms wrist module is proposed for humanoid service robots. This module, whose size and DOF configuration are consistent with humans, and adopts a cable-driven method to realize motion. The front part of the module provides a soft hand connection, and the module ends with a standard modular interface that enables the length of the humanoid arms to be reconstructed. The mechanical system of the wrist module has been developed, forward and inverse kinematics of the 3-DOF series-parallel structure is analyzed, a 3D printed physical prototype and control system is designed for the modular wrist experiment of pronation/supination, flexion/extension, and radial/ulnar deviation. Experiments show the 3-DOF series-parallel structure is capable of high fidelity humanoid wrist motion. This wrist module is designed to ensure lightweight and flexibility while improving the adaptability of the humanoid arm to different tasks, providing a new design idea for the humanoid arm to realize humanoid service applications.