Abstract: The wrist unit is crucial in humanoid robots, determining their operational dexterity and precision. To address currentchallenges such as excessive size, limited Degrees of Freedom (DoFs), and insufficient load capacity, we propose a 3-DoF humanoid wrist inspired by the human forearm and wrist anatomy. This paper explores the principles of wrist bionicdesign and introduces a parallel mechanism actuated by a brushless DC motor (BLDC)-ball screw to achieve flexion/extension(F/E) and radial flexion/ulnar deviation(R/U), as along with pronation/supination(P/S) through an end-couplingdesign. We conducted an analysis on the inverse kinematic model and singularities of the humanoid wrist. Additionally, the workspace and motion capabilities of the humanoid wrist were evaluated.A prototype based on this design was built to demonstrate its motion and functional performance, verifying the feasibility and practicality of the humanoid wrist. This research provides a more compact design approach for future humanoid wrist development.

Key words: Humanoid robots')">Humanoid robots, Humanoid wrist, Bionic design, 3-DoF