Analysis Of Motion Performance Of Shoulder Rehabilitation Mechanism With Spherical Scissors

At present,the number of diseases such as upper limb hemiplegia caused by stroke or periacromitis caused by long-term working on the desk is increasing.These diseases will lead to limited range of movement of the shoulder joint and seriously affect the normal quality of life.Therefore,timely and effective rehabilitation program is very important for shoulder joint to restore its movement function.In this paper,based on the biological structure,motion characteristics and medical rehabilitation theory of shoulder joint,the motion performance of series spherical scissors mechanism for shoulder joint rehabilitation is analyzed.Firstly,based on the anatomical theory of human shoulder joint,the structural characteristics of shoulder joint,the three basic motion forms of shoulder joint and the rehabilitation scheme of shoulder joint are analyzed.On the basis of this,the characteristics of degrees of freedom of the series spherical scissors mechanism are analyzed using the screw theory.The degree of freedom characteristics of the mechanism are consistent with that of human shoulder motion and its structure satisfies the requirements of shoulder rehabilitation.Secondly,the kinematics problem is analyzed according to the structure and motion characteristics of spherical scissors mechanism.The forward kinematics and inverse kinematics models of the mechanism are established by means of the combination of quaternion description method and D-H parameter method.The Jacobian matrix of the mechanism is solved,and the singular configuration of the mechanism is analyzed.The dexterity of the mechanism is analyzed by the performance indices of the condition number and manipulability.The parameters of the mechanism are set,and the workspace of the mechanism is solved by Matlab programming.Then,the static equilibrium equation of the shoulder rehabilitation mechanism with spherical scissors is established by the method of isolation analysis of each part of the bar,and the stress condition of each joint is obtained.Based on the finite element analysis theory,the finite element simulation analysis of shoulder joint rehabilitation mechanism is carried out using Ansys software.The stiffness of the mechanism is compared with that of the spherical 3R mechanism with the same mechanical and kinematic properties,It is verified that the stiffness characteristic of spherical shearing fork mechanism is better than that of spherical 3R mechanism.It provides a theoretical basis for further configuration optimization and improvement of the mechanism.Finally,the kinematics and dynamics simulation of shoulder flexion/extension,abduction/adduction and internal rotation/external rotation are carried out based on ADAMS software.The rehabilitation trajectory of the mechanism is planned using cubic spline function interpolation method.