| Lower limb rehabilitation robot is a kind of mechanical device used in rehabilitation medicine,which can enhance human muscle activity and strength,help patients recover lower limb movement function,and help the elderly improve walking ability.Because of the large population of the elderly and the patients with lower limb disabilities and the small number of professional medical rehabilitation personnel,it is of great significance to the development of lower limb rehabilitation robots.The structure of rehabilitation robot determines the performance of rehabilitation robot.In this paper,the structure of the robot is designed,and the performance of the mechanism is analyzed and studied.The structure and composition of human lower limbs are analyzed.The three main joints of human lower limbs,hip joint,knee joint and ankle joint,determine the movement mode and range of human lower limbs.The composition of the joints and the degree of freedom are analyzed.The walking simulation of human body is carried out by OpenSim,so the motion changes of human joint and the degree of freedom required for each joint movement in a gait cycle are obtained.According to the degrees of freedom required by the joints,the mechanism of the joints are designed respectively.In order to adapt to different height groups,the leg mechanism and thigh mechanism are designed and they can be able to adjust,and the overall configuration design of the lower limb rehabilitation robot is completed.Hip joint mechanism is the most important mechanism in the lower limb rehabilitation robot.A kind of UPS+UPR+S parallel mechanism is designed as the hip joint of the rehabilitation robot.The degree of freedom of the mechanism is analyzed by using screw theory.The constraint equation of the mechanism is established and the mechanism will not appear accompanying motion.The inverse kinematics equation of UPS+UPR+S parallel mechanism is analyzed.An example of inverse kinematics solution is given.The forward kinematics equation of UPS+UPR+S parallel mechanism is solved by genetic algorithm.The corresponding forward kinematics solution is obtained,and the results are in good agreement with the inverse kinematics solution.The velocity expression of the mechanism is obtained from the inverse equation,and an example is given by using MATLAB.The Jacobian matrix of the mechanism is deduced,and the singularity of the mechanism is solved.It is obtained that there is no singularity of the mechanism within the allowable range of motion.According to the boundary search method,the workspace of the mechanism is obtained by programming in MATLAB,and the workspace of the mechanism is simulated by SolidWorks,which verifies the correctness of solving the workspace.The dexterity of the mechanism is analyzed,and the distribution of local condition number which can be used to describe the dexterity of the mechanism is obtained.The dexterity distribution of the mechanism in the workspace is given,and the influence of the structural parameters of the mechanism on the global dexterity is analyzed.The static stiffness performance of the mechanism is analyzed,and the speed performance of the mechanism is studied.An experimental prototype is built and the rotation range of the mechanism is obtained.Adams software is used to simulate and analyze the hip joint mechanism,which verifies the correctness of kinematics analysis and conducts dynamic simulation research.A man-machine integration model of rehabilitation robot is built in SolidWorks,which is imported into Adams and a virtual prototype is created.Taking the joint rotation data of human walking simulation as driving data,the simulation study of the lower limb rehabilitation robot simulating human walking is carried out.The driving speed data of each driving point,the change curve of the centroid of each part of the human body and the change of driving force,moment and power are obtained,which provid the basis for further improvement of the rehabilitation effect. |
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