Design And Analysis Of Bionic Shoulder Joint Based On Spherical Parallel Mechanism

China is a country with the largest number of disabled persons,so it is of great scientific significance and urgent practical demand to develop practical upper limb prostheses for disabled patients.Bionic shoulder mechanism is an important part of the upper limb prosthesis.In this paper,a novel 3-RRR spherical parallel mechanism is used as the prototype of the bionic shoulder mechanism.The parameters of the mechanism are optimized by multi-objective design and the stiffness performance of the mechanism is analyzed.Based on this,a bionic shoulder experimental platform with anthropomorphic structure and function is designed,and the correctness of the bionic design principle and the rationality of the structure are verified through simulation and experiment.The research results of this paper have made an innovative breakthrough in the field of bionic shoulder joint and provided a new method for the design of bionic shoulder joint based on parallel mechanism.The main research contents are as follows:(1)Type selection and kinematics analysis of bionic shoulder joint mechanism.Based on the analysis of the motion form and motion range of human shoulder,a novel 3-RRR spherical parallel mechanism is proposed as a prototype of the bionic shoulder joint,and the forward and reverse kinematics are derived.(2)Multi-objective optimization design of bionic shoulder joint mechanism.The parameters of the mechanism were designed with the objectives of maximizing workspace,maximizing dexterity and minimizing maximum joint torque,and a set of Pareto optimal solution set was obtained.Multi-objective decision-making method is used to select the optimal mechanism parameters to meet the requirements.(3)Stiffness analysis of bionic shoulder joint mechanism.The Cartesian stiffness matrix of bionic shoulder mechanism considering the flexibility of linkage was derived by using the virtual spring method.The distribution of stiffness performance index in the workspace and the influence of actual structural parameters and material properties on global stiffness performance index are analyzed.(4)Design and functional verification of the experimental platform of bionic shoulder joint.According to the requirements of anthropomorphic structure and function,a virtual prototype of the experimental platform of bionic shoulder was designed.Static finite element simulation is carried out to analyze the strength and deformation of the structure,and kinematics simulation is carried out to realize the function of movement along the planned trajectory,the bionic shoulder experimental platform is built and the kinematic performance evaluation experiment is carried out to verify the rationality of the design principle.