Design And Optimization Of Knee Rehabilitation Exoskeleton

With the rapid development of exoskeleton technology,the requirements of motion fusion between the exoskeleton and human body are higher and higher,so as to meet the requirements of exoskeleton safety,comfort,and work efficiency.However,due to the complexity of man-machine coupling model and the complexity of knee joint,the motion fusion between exoskeleton mechanism and human joint remains to be solved.In this paper,from the point of view of the alignment of the motion axis of the human joint and exoskeleton,according to the kinematic characteristics of knee joint,a knee exoskeleton based on parallel mechanism and cable-driven conjugate surface is designed.Firstly,the kinematics of the mechanism are analyzed by using the screw theory,and the consistency between the number and nature of degrees of freedom of the mechanism and the knee joint is verified.The forward and inverse kinematics solutions and first-order influence coefficients of the mechanism are obtained,which lays a foundation for the following axis motion fusion algorithm;The solution formulas of conjugate surface joint fixed surface and moving surface are deduced,and the solution method and process of discrete fixed surface and moving surface are given.Secondly,based on the screw theory,a mechanism parameter selection method is proposed,which can obtain all the changeable scale parameters of the mechanism without affecting the degree of freedom of the mechanism;According to the kinematic parameters of the mechanism and the force characteristics of the human body when walking,combined with the particle swarm optimization algorithm,based on the motion/force transmission performance index and the minimum peak driving force,the dimension optimization of the parallel mechanism and conjugate surface joint of the exoskeleton mechanism are carried out respectively.Finally,an axis adaptive algorithm based on motion manifold for exoskeleton is proposed.By measuring the twist of human joints,the tangent space on the motion manifold of human joints is established,and then the motion manifold of human joints is established;The algorithm can plan the coupling motion of human joints with decoupled parameters,which can effectively improve the motion fusion between man and machine.Finally,the correctness and accuracy of the algorithm are verified by simulation.