An Actuated Spherical Joint for Humanoid Robotics Applications

A newly developed actuated spherical joint is introduced for application in the field of humanoid robotics. The mechanism consists of a parallel structure with four limbs in a 3PSS-1S kinematic configuration. This, allows to perform rotations with respect to any arbitrary axis passing through the center of the joint, effectively implementing a spherical motion. By having the actuation system located on the fixed platform allows maximizing the payload and reducing the energy consumption. The solution of the inverse kinematics is provided together with simulation results conducted in V-REP. It is shown how parameters like the moving base diameter and the links length influence the workspace of the mechanism. A first prototype is presented together with preliminary results showing a rotation range of ±45 ° about the pitch and roll axes and 120° about the yaw axis.