Research On Performance Optimization Of Knee Joint Exoskeleton Tensioning System Based On Wearability

As a mechanical device connecting human body and exoskeleton robot,the knee exoskeleton tensioning wearable system has a wide application prospect in the field of sports health of patients with knee osteoarthritis.In order to improve the wearing comfort,bearing effectiveness and dexterity of the knee exoskeleton,this paper designs a new type of knee exoskeleton tensioning wear system.Based on the research prototype of the system,through the joint simulation of Ansys Workbench,Matlab and Rhino platform,the performance optimization method of the tensioning wear system considering the wearing comfort of the exoskeleton is carried out :Firstly,based on the analysis of human lower limb movement mechanism,a bionic research prototype of knee exoskeleton tensioning wearable system is proposed.Based on the D-H method,the mathematical model of the rigid armor layer in the tensioning wearing system is built,and the kinematic simulation analysis of the end motion of the rigid armor layer is carried out on the MATLAB software platform to verify the correctness and effectiveness of the mathematical model.In order to improve the accuracy of the model,based on the ANSYS Workbench software platform and the principle of functional equivalence,the knee exoskeleton tensioning wear system is divided into a nonlinear human-machine contact unit and an overrunning clutch drive unit for dynamic/static simulation optimization,which lays a theoretical foundation for the subsequent wearable comfort index.Secondly,based on the static simulation data of the nonlinear human-machine contact element finite element model,a new wearable comfort evaluation index considering the factors such as stress,deformation and the proportion of stress nodes is constructed.Based on the virtual prototype simulation of the system,the initial data population of the optimization of the wearing parameters of the system buffer layer is obtained,and the multi-objective genetic optimization of the parameters is carried out in combination with the wearing comfort.Based on the above virtual prototype sub-model,the local optimization of the system armor layer topology is carried out on the Ansys Workbench platform with the comprehensive goal of stress uniformity and light weight.According to the virtual prototype simulation based on two optimization synthesis and the data analysis and comparison before and after optimization,the optimized exoskeleton has better static wearing comfort.The research results can provide a theoretical basis for the subsequent research on the bearing comfort of exoskeleton tensioning wearable system.Finally,based on the dynamic simulation of the multi-body finite element model of the overrunning clutch of the core driving component of the tensioning system,a new dynamic wearing comfort evaluation index is proposed,which takes into account the transition time of the tension vibration,the weighted root mean square value of the normal acceleration and the maximum normal average pressure.The structure of the overrunning clutch drive unit was optimized using the Design Xplorer tool.Based on the dynamic wearing comfort evaluation index,the multi-objective genetic optimization of the system is carried out on the Matlab and Rhino platforms.By comparing the data before and after optimization,it is proved that the optimized tensioning wearable system has better dynamic performance and the reasonable effectiveness of the research method.The research results also have important guiding significance for the further detailed design and construction of its prototype system.