Structure Design And Stability Study Of The Lower Extremity Exoskeleton Robot

With the very fast development of modern science and technology,and the increasing advancement of the life level of people,exoskeleton is aimed at combining human intelligence with machine power,which is concerned by more and more countries,enterprises and scientific workers.Due to the lower extremity exoskeleton robot in exoskeleton has shown great application prospects in many fields such as military,medical and civil applications,its development is particularly rapid.At present,the foreign lower exoskeleton robot has been sold in the market,and the domestic lower extremity exoskeleton robot is still in the laboratory research stage,but there are still many problems,such as mechanical structure,movement intention recognition and stable walking in the exoskeleton,which have not been solved well.This paper is to design a lower limb exoskeleton robot to assist walking,which is used to assist normal people having lower power in his/her lower limb,such as the elderly.In order to achieve this goal.At first,we investigate the existing research results and analyze the composition and working principle of the main current lower limb exoskeleton system at home and abroad.Secondly,the human body composition and the mechanism of the lower limb movement are studied.After completing the above of work,we set the overall plan of the exoskeleton mechanical structure design and the three-dimensional model is established by using SOLIDWORKS.Considering the safety of the structure,the structure designed is analyzed to check the strength and rigidity of the structure by using the finite element analysis.In order to ensure that the exoskeleton can realize the common movement of human body,the kinematics of exoskeleton is analyzed.At the same time,we verify the correctness and feasibility of its kinematics by using MATLAB Robotics.In view of the problem of stable walking in the exoskeleton of the lower extremities,the most widely used ZMP theory is studied.We prove that the ZMP theory is only a sufficient and necessary condition of static stability and dynamic transient stability,but not a sufficient and necessary condition for dynamic continuous stability.According to the shortcomings of the current ZMP theory in dynamic continuous stability,a dynamic continuous stability criterion combining walking double support ZMP with single support virtual ZMP is proposed.In addition,in view of the dynamics of the interaction between the external skeleton and the human,the dynamic equation of the man-machine coupling is established by Lagrange dynamic analysis method.Therefore,we get the rule of joint torque and joint power in a walking cycle by compiling the dynamic equation program in MATLAB.Finally,In order to verify the correctness of the established man-machine coupling dynamic model,a man-machine coupling dynamic model is set up in ADAMS.The correctness of the model is verified by the comparison of theoretical analysis and simulation results,which can provide important theoretical reference for the further study of the extremity exoskeleton robot.