Coupled Bionic Design And Research Of Stiffness Control For Exoskeleton Walking Robots

At present,exoskeleton walking robots generally adopt rigid body structure.Rigid exoskeleton walking robots are tively heavy to wear,esulting in rigid gait,reducing the comfort of wearers,and limiting the practical application of exoskeleton walking robots.The paper uses coupled bionic characteristics with human on the flat ground and stairs to design the exoskeleton walking robot with stiffness control.The main research contents are as follows:(1)Obtaining rotation angles of hip joint,knee joint and ankle joint of human lower limbs,joint angular velocity and angular acceleration when human moves on flat ground and step terrain.When human walks on the flat ground,rotation angles of left leg joints:0?24.9°,0.7?63.2°,-0.7?24.0°,rotation angles of right leg joints:0?28.1°,5.3?72.8°,-5.4?32.1°.When human walks up the stairs,rotation angles of left leg joints:0.5?44.0°,17.8?87.4°,-10?24.3°,rotation angles of right leg joints:0.1?40.9°,12.9?91.40,-12.6?18.8°.When human walks down the stairs,rotation angles of left leg joints:11.1?34.0°,15.3?84.3°,-16.7?25.8°,rotation angles of right leg joints:5.6?30.7°,13.7?88.3°,-23.4?30.7°.(2)Studing dynamics characteristics of human lower limbs by Matlab SimMechanics.Obtaining torques of hip joint and knee joint of human lower limbs.When human walks on the flat ground,peak torques of left leg joints are 130N·m,57N·m,peak torques of right leg joints are 159N·m,60N·m.When human walks up the stairs,peak torques of left leg joints are 233N·m,75N·m,peak torques of right leg joints are 270N·m,83N·m.When human walks down the stairs,peak torques of left leg joints are 110N·m,45N·m,peak torques of right leg joints are 125N·m,52N·m.(3)Calculating the stiffness of human lower limbs by the Morin stiffness model.When human moves at a slow,constant and fast speed,stiffnesses of lower limbs for walking on the flat ground are 2.84?7.80KN/m,3.72?9.38KN/m and 3.01?10.19KN/m;Stiffnesses of lower limbs for walking up the stairs are 1.30?4.01KN/m,2.14?5.39KN/m and 2.57?7.95KN/m;Stiffnesses of lower limbs for walking down the stairs are 1.20?7.71 KN/m,2.34?10.27KN/mand 3.40?17.98KN/m.(4)Desgining the exoskeleton walking robot with stiffness control according to kinematic characteristics,dynamic characteristics and stiffness characteristics of human lower limbs.Building three-dimensional model of the exoskeleton walking robot and human-machine wearing coupling model.Using ADAMS to do dynamic simulation analysis of human-machine wearing.When human-machine wearing coupling model walks on the flat ground,stiffnesses control range of the exoskeleton walking robot are 0.02?36.91KN/m,0.01?12.56KN/m,0.09?38.25KN/m and 0.01?10.39KN/m.When human-machine wearing coupling model walks up the stairs,stiffnesses control range of the exoskeleton walking robot are 0.03?53.40KN/m,0.02?19.49KN/m,0.07?65.93KN/m and 0.03?25.34KN/m.When human-machine wearing coupling model walks down the stairs,stiffnesses control range the exoskeleton walking robot are 0.13?40.55KN/m,0.03?20.92KN/m,0.08?46.10KN/m and 0.06?18.48KN/m.Studing stiffness control of the exoskeleton walking robot with kinematic characteristics,dynamic characteristics and stiffness characteristics of human lower limbs.Improving coordination and accommodation problem of human-machine movement.This has important scientific significance,social value and application prospect.