Design And Research Of An Exoskeleton Robot For Lower Limb Disability Based On Metamorphic Principle

With the increasingly severe aging of the population,the number of elderly people with poor flexibility and even disability of lower limb joints due to functional decline is increasing.In this thesis,a lower limb disabled exoskeleton robot which can assist human walking and squatting in two rehabilitation training functions is proposed for this kind of lower limb movement disabled people,and the design and research of the lower limb exoskeleton robot are carried out.The main research contents are as follows:The bionic design of a lower limb exoskeleton robot is based on the structural characteristics and motion mechanism of human lower limb joints.The initial configuration is designed as a series-parallel hybrid structure,the hip and ankle joints with multiple degrees of freedom are designed as a two-degree-of-freedom parallel mechanism,and the knee joint is designed as a single-degree-of-freedom rotation motor direct-driven structure;On the basis of the initial configuration of the exoskeleton,the metacellular synthesis design was carried out.With the feature that the metamorphic mechanism can deform according to different working environments,thus realizing multiple functions,the metamorphic principle is introduced into the design of the exoskeleton,so that it can realize two functions of assisting the human body to walk and squat.Finally,the overall structure design of the lower limb disabled exoskeleton robot was completed.The kinematics of the developed lower limb exoskeleton robot was analyzed.Decoupling the global exoskeleton kinematics model to the front and rear models,and simulating the front and rear models in the front and rear kinematics respectively;Using D-H parameters to analyze the local kinematics of hip ankle parallel joints;Using MATLAB and ADAMS software,test the accuracy of parallel joint motion models through joint modeling;Finally,the workspace of the hip and ankle joint parallel mechanism is solved by three-dimensional search method.Based on the ZMP maximum stability margin method,the gait planning of the designed exoskeleton robot is carried out.Through the posture of the main nodes of the exoskeleton robot at the critical moment,the spline interpolation method is used to plan the motion trajectory of each joint in the whole gait cycle;Secondly,the front and lateral ZMP coordinates of the exoskeleton are calculated,and the hip joint trajectory parameters are optimized by the ergodic method to find the gait trajectory of the exoskeleton robot and the motion of each joint driver under the maximum ZMP stability margin.Through ADAMS virtual prototype technology,the gait simulation and squatting simulation of the designed lower limb exoskeleton robot virtual prototype are carried out,the stability of the exoskeleton robot’s step and the reliability of squatting are tested,and the rationality of the kinematics model and motion planning method is verified;ANSYS Workbench is used to carry out static and modal analysis on four typical states of exoskeleton robot,to verify whether the strength and stiffness of the exoskeleton robot mechanism meet the safety requirements,and whether its structural design is reasonable,and solve the natural frequency and vibration mode of the mechanism.