Bionic Design And Study Of Flexible Joint With Variable Stiffness

With the development of Industry 4.0 and the advance of Machine Substitutions,there are higher requirements for robots and their key components.The flexible joint with active variable stiffness has become one of the key components for enhancing the performance of robot.The study is one of the hot points in the research fields of robot.The thesis focuses on the design and study of flexible joint with active variable stiffness in the context of the lower extremity of human beings in normal walking gait.The main work is as follows.1.According to the walking gait and structural characteristics of the lower extremity,the structural parameters of the lower extremity is determined.Simultaneously,the kinematics and dynamics mathematical model of lower extremity are established,and the angular displacement and joint torque of the joints of lower extremity are obtained respectively.2.The driving mechanism of flexible joint is designed by analytic method.Based on the five-bar mechanism's Grash of criterion,the movability is analyzed.Based on the mechanism singularity principle,the singularity is analyzed.3.The kinematics model of the driving system is established by the analytic method.The kinematics model of the bionic hip system is analyzed by the geometric analytic method.Based on The Law of Newton and D'Alembert's principle,the dynamic equation of the bionic hip system is established.Simultaneously,the dynamic model of the driving system and the equivalent stiffness are established.4.The three-dimensional model of lower extremity and driving system are established by ProE,and the motion simulation can be carried out in MATLAB/SimMechanics.The hip joint torque of lower extremity and the binding force of the driving system are obtained by simulation.At last,the virtual prototype of flexible joint with active variable stiffness is established by ProE.The motion simulation is carried out in ADAMS,and the joint angle of flexible joint is obtained by simulation.The correctness of the design about flexible joint is verified,and it is provided about the theory and guidance for the manufacture of physical prototype.The thesis combines the characteristics of the bar mechanism and the cable to design a bionic flexible joint for the lower extremity,which provides a new idea for the flexible actuator of the lower extremity.