Novel design of a 3-DOF series-parallel torso for humanoid robots

A novel 3-dof series-parallel torso is proposed for humanoid robots to realize multimode locomotion and transition. The torso is composed of a 2UPU-U parallel mechanism for pitch and roll rotation and a serial joint for yaw rotation. The working principle of 2UPU-U is analyzed and a kind of integral joint base on rimless servo motor is designed in details. The proposed torso can not only improve the motion performance and flexibility of humanoid robot but also ensure the load capacity and servo accuracy.