Design And Research On Cable-Driven Lower Limb Rehabilitation Exoskeleton Robot

With the increasing number of limb dyskinesia patients and the more pressing need of treatment for clinical rehabilitation,the research and development of lower limb rehabilitation robots have been widely concerned by scholars at home and abroad in recent years.How to equip the lower limb rehabilitative robots with the abilities of self-adaption,human-machine cooperation and flexible control is an urgent problem to be solved at present.Under the above background,this thesis aims to design a lower limb rehabilitation exoskeleton robot drived by extension-type cables.The theoretical analysis and simulation studies are carried out,the main work is as follows:(1)The normal human walking gait signals are collected by Xsens MVN inertial motion capture system.On the basis of research on human anatomical structure,the forward kinematics and inverse dynamics model of human lower limb are established.Considering the influence of the ground force,joint torques of walking lower limb are solved based on the non conservative Lagrange equation.The inverse dynamics simulation is carried out through Simmechanics.The results verify the accuracy of joint torques calculation,and provide the data source for this thesis.(2)According to the mechanism of lower limb movement,a general plan of the lower limb rehabilitation exoskeleton robot which drived by extension-type cables is put forward.The structure design of adjustable exoskeleton and movable frame,cable-driven joints modularized configuration design and drive mechanism design are completed according to the range of joints motion and the ratio of height to adult's each body segment.Meanwhile,the connection mode of extension-type cable is determined,which lays a model foundation for analysis and researches.The static analysis of key parts is carried out by ANSYS Workbench and the verification results show that the structural design can meet the strength requirements.(3)The theoretical model of cable-driven joints is analyzed,and the variation rule between the cable length and joint angle is obtained through inverse position analysis.On the basis of mechanical analysis,the problem of cable tension distribution is solved,and the P-norm approximation and orthogonal complement method are used to achieve the optimal solution of cable tension.Then the influence of casing friction with constant curvature and variable curvature on cable driving is analyzed by means of infinitesimal method.A simple and compact column type variable stiffness module is designed,and the design expectation is verified through stiffness analysis,which provides theoretical support for simulation researches.(4)The virtual prototype of the lower limb rehabilitation exoskeleton robot is built in ADAMS,and the simulation experiments are carried out based on the cable length variation and the tension force respectively.By comparing the change of joints angles,the rationality of the model design and the correctness of theoretical analysis are demonstrated.Finally,the adaptive iterative learning control system is designed according to the characteristics of the patients' passive walking rehabilitation training,and the joint simulation control experiment is implemented by use of Simulink.The results verify the tracking performance of this control method on the joints desired trajectories and the controllability of the lower limb rehabilitation exoskeleton robot.