Structure Design And Simulation Analysis Of Lower-limb Exoskeleton-assisted Robot

Exoskeleton-assisted robot is a popular research object in auxiliary walking products at present,in this project,the lower-limb exoskeleton-assisted robot is studied,which is better flexible and comfortable and conforms to the level of mass consumption.By means of theoretical analysis,modeling calculation and simulation verification,this dissertation focuses on the structural design,kinematics and dynamics analysis,finite element analysis and co-control simulation of the exoskeleton-assisted robot.The mainly research work and results are as follows:Based on the analysis of the structural properties and movement mechanism of human lower limbs,the bionic design of the mechanical system of the exoskeleton-assisted robot has been carried out,and a lower-limb exoskeleton-assisted robot with adjustable structure size,anthropomorphic freedoms,and a buffered vibration damping device is designed;According to the human gait data,the Maxon EC 90 disc motor and the Planetary Gearhead GP 52 C reducer are selected as the driving mode of the active joints finally.In addition,an embeded exoskeleton-assisted robot control method is proposed,which can easily and efficiently realize the function goals of synchronous follow and saving effort;Finally the mechanical system and driving system of the robot are modeled by UG.Based on the D-H parameter method and the differential transformation method,the positive and inverse kinematics of the exoskeleton-assisted robot are analyzed,which obtain the motion characteristics of the lower-limb active joints of exoskeleton;Lagrange's method is used to analyze the inverse dynamics of the exoskeleton,the torque analysis formulas of the flexion/extension motion of the active joints are obtained,which provide a mathematical theoretical basis for the selection and design simulation of the control method;A rigid-flexible coupled virtual prototyping model of the exoskeleton-assisted robot is established in ADAMS,the kinematics and dynamics theoretical analysis results are verified,and the man-machine coordination performance and buffer damping function of the robot are verified and analyzed,the results show that the man-machine coordination performance is perfect,and the damping effect meets the design requirements,the maximum impact force is only 1/6 of the original.The static analysis of the mechanical structure of the exoskeleton-assisted robot under four different gaits are carried out by using ANSYS Workbench.By optimizing the local structure of robot,the safety factors of the mechanical structure are all greater than 1,which ensures that the structural strength and stiffness are reasonable;Under the condition of non prestress and prestress,modal analysis of the exoskeleton-assisted robot with standing phase and double support phase are performed to obtain the natural frequency and mode shape of the structure,the results show that the exoskeleton has larger deformation displacement in the position of the load connecting rod and the hip joint.The transient dynamic analysis of the exoskeleton is carried out,the maximum deformation and the maximum stress occur at 0.2 s,and the safety factors are all greater than 1.5,the results show that the structure of the robot satisfies the requirements of strength and stiffness under the action of instantaneous impact force.The fuzzy adaptive PID control is selected as the trajectory tracking control method for the joint motion of the exoskeleton-assisted robot;In Simulink,the traditional PID controller,fuzzy controller and fuzzy adaptive PID controller are designed and simulated.The results show that the fuzzy adaptive PID simulation curve has a faster response rate and a smaller overshoot;Based on ADAMS and Simulink,co-simulation model of exoskeleton is established,which proves that the lower-limb active joints of exoskeleton have good joint response characteristics and motion follow abilities,and the mechanical dynamics model and control system model can accurately describe the work process of exoskeleton.The structure of the lower-limb exoskeleton-assisted robot finally designed is simple and reasonable,and has a good human-machine coupling performance.It can cooperate with the old people to complete the common movements such as walking,squatting/standing and so on,so that the elderly will no longer suffer from the inconvenience of traveling,and regain normal walking abilities.To a certain extent,it relieves the burden caused by the aging problem on family and society,and has great economic and social values.