Design of a humanoid shoulder mechanism without a gliding shoulder blade architecture
Recent developments in humanoid robotics have lead to shoulder mechanisms with a gliding shoulder blade ar- chitecture. Such mechanisms are overly compliant and therefore difficult to control. The goal of this paper is to develop and validate a parallel shoulder mechanism. A shoulder model is defined where the shoulder blade glides on an ellipsoid surface. The gliding model is replaced with an equivalent parallel model and simplified. The simplified system is a 3-3 parallel platform. The forward kinematics problem is solved using a minimal set of independent coordinates that provide flexibility in motion design. The mechanism trades compliance with stiffness but is shown to imitate the shoulder, namely reproducing the scapulo-humeral rhythm, primary characteristic of shoulder kinematics.