Motion Performance Analysis And Optimization Design Of Parallel Ball And Socket Joint Rehabilitation Mechanism

Parallel mechanisms have been widely used in the field of medical rehabilitation because of their good kinematics and dynamics.Based on the performance requirements of the ball and socket joint rehabilitation mechanism,this paper analyzes the configuration and structure of the parallel mechanism that meets the requirements.The 2-SPS+RRR parallel mechanism is selected for kinematics analysis,motion simulation,and size parameter optimization.Firstly,by consulting the biological literature,the physiological structure and movement form of the ball and socket joint are studied,and combined with the traditional rehabilitation treatment,the performance and requirements of the parallel mechanism suitable for the rehabilitation of the ball and socket joint of the human body are obtained.Secondly,by analyzing the existing configuration synthesis theory,the model synthesis method based on G_F set theory is used for configuration synthesis.First,using the G_F set law and the intersection algorithm,the configuration integrates a parallel mechanism with three rotation characteristics.Then,the original branch is transformed by the axis migration theorem and the motion pair replacement.Finally,the parallel mechanism suitable for ankle rehabilitation is selected from the integrated configuration to optimize its structure.Then,the 2-SPS+RRR parallel mechanism is selected from the optimized configuration for kinematic correlation analysis.The degree of freedom is calculated by using the spiral theory and the modified G-K formula.Then the relationship between the moving platform and the branch is established by the D-H parameter method and the geometric relationship method,and the position inverse solution calculation of the mechanism is performed.Thirdly,based on Matlab and SolidWorks software,the boundary limit search method is used to find the reachable workspace of the mechanism.Comparing the workspaces obtained by the two methods,the size and shape of the workspace are basically the same,which verifies the correctness of the workspace.Finally,a virtual prototype of the 2-SPS+RRR parallel rehabilitation mechanism was established by ADAMS to perform kinematics simulation,and then the displacement,velocity and acceleration of the rehabilitation platform were analyzed.Finally,based on the genetic algorithm,the selected 2-SPS+RRR parallel rehabilitation mechanism is optimized for size parameters.Firstly,the effects of various parameters of the organization on the X,Y,and Z directions of the workspace and the overall workspace are studied.Then,the size of the workspace is set as the objective function by genetic algorithm,and the number of individuals,genetic algebra,etc.The parameters are used to solve the global optimal solution of the parallel mechanism size parameters.Finally,the optimized workspace of the parallel rehabilitation mechanism is compared with the workspace before optimization.The optimized space is better than the previous one in the X,Y and Z directions.Through the research in this paper,the GF set theory configuration is used to synthesize the parallel mechanism with three rotation characteristics,which has certain reference value for the selection of parallel ball and socket joint rehabilitation mechanism.At the same time,the application of the 2-SPS+RRR parallel mechanism for the ankle joint rehabilitation is carried out.The kinematics calculation and simulation are carried out to prove that it has good kinematics performance,and the size parameters are optimized by genetic algorithm.The design provides a theoretical basis for the future design and practical application of the organization.