Design And Research Of Parallel Mechanism For Ankle Joint Rehabilitation

The ankle joint plays a very important role in all the joints of the human body.It is the joint that bears the greatest load of the human body.Nowadays,as the problem of aging gets worse and the number of people who suffer from ankle injuries due to the exercise process,this article aims at the deficiency of the domestic and foreign ankle rehabilitation mechanisms and designs a new structure for the rehabilitation of ankle joint,and carries out the design and performance analysis of the mechanisms,so that patients can carry out effective rehabilitation exercise.The main research contents are as follows:The physiological structure and kinematic ability of human ankle joint were analyzed,and the normal range of motion of ankle joint was known to be the freedom of rotation around three axes and one degree of passive drafting freedom.According to the design requirements of ankle rehabilitation mechanism,a 4-UCU/RPRR parallel ankle rehabilitation mechanism is designed to meet the needs of rehabilitation movement of three rotations and one shift.Three kinds of rehabilitation exercises can be carried out for the damaged ankle joint,namely dorsiflexion/plantarflexion,inversion/eversion,adduction/abduction.The center of rotation of the ankle joint coincides with the center of rotation of the mechanism,which can avoid the secondary injury of the damaged ankle joint in the process of rehabilitation training and realize the rehabilitation training for the ankle joint.The kinematic analysis of the ankle joint rehabilitation mechanism was carried out,The degree of freedom of the rehabilitation mechanism was calculated by means of the spiral theory,and the G-K formula was used to validate the freedom of the mechanism,indicating that the mechanism has four degrees of freedom.Then,the inverse and forward solutions of4-UCU/RPRR are analyzed by means of closed vector and PSO,and then the time derivatives of the inverse position solution equation were obtained to solve the velocity jacobian matrix.Finally,Matlab software is used to analyze the work space of the mechanism.It can be seen that the working range of the mechanism is large,and there is no cavity or singularity,indicating that the working performance of the mechanism is good.Then,the kinematics of the parallel mechanism is simulated.The virtual prototype was built by Adams Simulation Software,and the degree of freedom of the mechanism was checked again to prove that the mechanism configuration was reasonable.Through the forward kinematics analysis of the mechanism,the curve of displacement,speed and angle is obtained through the simulation analysis.There is no break point or mutation point,and the curve is continuous and smooth,indicating that the mechanism is stable and safe in the rehabilitation training,with good performance.The inverse kinematics of the mechanism is analyzed,and the forward kinematic simulation results are validated through the analysis of the variation of the displacement of the branches,which showed the correctness of the kinematics simulation.To evaluate the rehabilitation effect of rehabilitation mechanisms.Any Body is used to build a man-machine model to simulate the rehabilitation of Any Body in three kinds of ankle exercises.Through the analysis of the change curve of muscle activity,expansion and muscle force during rehabilitation training,it is found that the curve changes are in a reasonable range,and in line with the requirements of human rehabilitation training,indicating that this mechanism has a good rehabilitation training effect,and can carry out rehabilitation exercise training on the damaged ankle joint.