Kinematic Synthesis and Modeling of a Three Degrees-of-Freedom Hybrid Mechanism for Shoulder and Hip Modules of Humanoid Robots

This paper deals with a research work that aims to develop a new three degrees-of-freedom (DoF) hybrid mechanism for humanoid robotics application. The proposed hybrid mechanism can be used as a solution not only for several modules in humanoid robots but also for other legged robots such as quadrupeds and hexapods. Hip and shoulder mechanisms are taken as examples in this paper; torso and spine mechanisms, too, can be based on the proposed solutions. In this paper, a detailed analysis of the required performances of the hip and shoulder mechanisms is first carried out. Then, using a kinematic synthesis, a novel solution for the hip mechanism is proposed based on one rotary and two linear actuators. Improving this solution allows us to fulfill the requirements induced by the large motion ranges of the shoulder module, leading to a new management of the linear actuators contributions in the motion/force achievement process. Kinematic and geometrical models of a generic hybrid mechanism are achieved and used to get the optimized solutions of both hybrid mechanisms addressed in this paper.