| As a wearable human-machine parallel mechanical device,the lower limb knee exoskeleton robot cleverly integrates the power-assisting ability of exoskeleton with human intelligence,and has a wide market prospect in the fields of helping the elderly and the disabled and sports rehabilitation.This paper takes the shortcomings of existing knee exoskeleton devices as the starting point,and based on the research prototype of lower limb knee exoskeleton,based on the study of human lower limb motion mechanism and human lower limb parameters,the corresponding research is carried out for the wearable characteristics of the lower limb knee exoskeleton robot itself.First,based on the analysis of human lower limb motion mechanism,a lower limb knee exoskeleton bionic research prototype was proposed;a mathematical model of the overall knee exoskeleton system was built based on the D-H method,and kinematic simulation analysis was conducted in MATLAB 9.0 software platform and UG NX 12.0 virtual prototype software platform,thus verifying the correctness and validity of the mathematical model construction;then Based on the kinematics,the system dynamics analysis was carried out,and the system dynamics equations were established by using Lagrange’s equation method to calculate the coordinates,velocity,kinetic energy and potential energy of the center of mass of each rod,and solve the driving torque required by the joint,which laid a theoretical foundation for the subsequent system dynamics analysis.Secondly,based on the kinematic and load-bearing characteristics of the human lower limb,a bionic system of underdriven five-bar mechanism of the knee exoskeleton with kinematic inclusion and load-bearing effectiveness is proposed based on the prototype of lower limb knee exoskeleton bionic research;then,based on the velocity Jacobi matrix derived from the kinematic model of the system,the singularity shape,operability and full domain performance indexes of the mechanism are established.A new comprehensive evaluation index for evaluating the global workspace inclusive dexterity of the bionic mechanism is proposed,and a numerical optimization simulation of the structural parameters of the system is carried out on the MATLAB 9.0 platform with the optimization target.The validity of the kinematic analysis is verified by error analysis,and the in-depth analysis of the data shows that the optimized bionic mechanism has good bionic dexterity inclusiveness with respect to the human knee joint motion space,which also demonstrates the effectiveness of the structural parameter optimization method based on the new comprehensive evaluation index.Finally,based on the ANSYS Workbench 17.0 software platform,the multi-body dynamics simulation study of the bionic mechanism is conducted,and the initial spring stiffness and damping coefficients are given based on the relevant literature studies,and then the changes in the load-bearing capacity of the exoskeleton are compared by changing the stiffness damping coefficients of the support springs in the exoskeleton,and it is found to have good load-bearing capacity,which verifies that the bionic mechanism It was found that the exoskeleton has good load-bearing capacity,which verified the rationality and load-bearing effectiveness of the prototype structure design and provided data reference for the subsequent detailed design of the exoskeleton. |
