Design and simulation of a waist–trunk system for a humanoid robot

In this paper, a novel waist–trunk system has been proposed for a humanoid robot by using parallel architectures. The structure of human torso and its function during movements have been considered to gain biology inspirations for design purposes. The proposed waist–trunk system consists of a 3 legged UPS orientation parallel platform and a 6 legged UPS parallel platform, which are connected together in a serial chain architecture. The proposed design solution makes use of the advantages of known parallel architectures with a novel assembly solution as compared with traditional humanoid torso design solutions for humanoid robots in terms of high degrees of freedom (d.o.f.), high payload to weight ratio, high stiffness and accuracy, as well as better dynamic performances and easy-to-control features. A 3D model of the proposed system has been elaborated in SolidWorks® environment both for design and simulation purposes. Kinematic equations of the system have been formulated for characterization and evaluation of operation performances. Simulation results show that the proposed system is able to properly imitate different movements of human torso with suitable motion capability, flexibility, versatility, and operation performances.