Research On The Dynamic And Biomechanical Characteristics Of Passive Lower Extremity Ankle Joint Exoskeleton

Passive lower extremity exoskeleton is a device that assists the human body in walking.The auxiliary device does not rely on active driving components such as motors,and can provide assistance for human walking and reduce walking metabolic energy consumption.Human body wearing passive lower extremity ankle joint exoskeleton is a complex bio-mechanical coupling system.During human walking,the exoskeleton will change the joint dynamics and the biomechanical properties of the main muscles of the lower extremities.In this project,the dynamic and biomechanical characteristics of a passive lower extremity ankle joint exoskeleton based on clutches and extension springs are studied,and the assist mechanism of the exoskeleton to human walking is analyzed.The thesis work is mainly as follows:(1)Analyze the anatomy of the human lower extremities from three aspects: the structure of the human lower extremities,the main muscles of the lower extremities,and the gait cycle.The musculoskeletal model of the human lower extremities is established based on the Opensim biomechanical simulation software.The three-dimensional coordinates of the lower extremity motion control points and the ground The reaction force is driven to complete the simulation of the lower limb movement under the normal gait movement of the human body.Through the motion analysis of the human musculoskeletal model,the joint angle of the hip,knee and ankle joints and the muscle strength of the main muscles of the lower limbs under normal gait are obtained.(2)The mechanical structure and working principle of a passive lower extremity ankle joint exoskeleton based on a clutch and a tension spring were studied.A simplified model of a human-exoskeleton seven-bar linkage was established.The dynamic model of the supporting phase of the legs,using Admas simulation software to establish a biped walking model with passive lower extremity ankle exoskeleton,kinematics and dynamics simulation of the model,the kinematic characteristics and dynamics of the biped walking model were analyzed The characteristics of the joint torque changes after wearing the passive lower extremity ankle joint exoskeleton,which theoretically shows that the passive lower extremity ankle exoskeleton can provide torque for the human ankle joint in the middle of walking support,so as to achieve the effect of boosting.(3)Using Opensim biomechanical simulation analysis software to establish a biological-mechanical coupling equivalent human-machine model of the passive lower extremity ankle exoskeleton of human body and perform motion simulation,and analyze the muscle strength and muscle activity of the main muscles of the lower limb of the human body before and after wearing the exoskeleton,The changes of muscle contraction speed and metabolic energy,and analyzed the influence of wearing exoskeleton on the biomechanical properties of human lower extremities.The results show that the passive lower extremity ankle joint exoskeleton can reduce the muscle activity at the ankle joint,and reduce the loss of walking metabolic energy by reducing muscle activity.