Design And Optimization Analysis Of Passive Power Knee Exoskeleton Based On Fluid Spring

Knee joint is the most complex and heaviest joint in human lower limbs.There are many complex ligaments and almost no muscles on the knee joint,so it is easy to cause injury and disease due to lack of protection.Knee joint disease and strain will directly affect the human movement ability and daily life.Knee exoskeleton is a kind of wearable human motion aid device,which has no traditional driving element-s such as electric or hydraulic.It can provide extra power for the lower limbs and reduce the fatigue and damage of the knee joint.In this paper,a passive lower limb knee exoskeleton based on hydraulic fluid spring is studied.Gear meshing and cam-mechanism are used as the transmission unit to make the exoskeleton move synchron-ously with the knee joint.The principle of fluid spring is used as the driving mode of exoskeleton to store energy when the knee joint is flexing and release energy auto-matically when the knee joint is extending,so as to assist the knee joint The purpo-se of the movement.The main work of this paper is as follows:(1)A mechanical structure of passive lower limb knee exoskeleton based on hyd-raulic fluid spring is designed.The three-dimensional model of knee exoskeleton is e-stablished by Solid Works software,and the design and verification of fluid spring of driving unit are completed.(2)The fluid spring hydraulic system was established by AMESim to analyze th-e fluid movement.The working characteristics of the hydraulic fluid spring system were analyzed when the human body walked,squatted,stood up and sat up.The eff-ects of different piston rod diameters on the performance of the fluid spring were co-MPared.The performance of the piston type and push rod type fluid spring in the a-ctual situation was co MPared by simulating the human movement process working a-bility.(3)The meshing position of the hydraulic cylinder,push rod and gear of the kn-ee exoskeleton was analyzed by ABAQUS software to verify the structural safety of the exoskeleton driving parts and transmission parts,and the topology optimization of the knee bracket was carried out.(4)In order to get the influence of wearing knee exoskeleton on the biological characteristics of hip joint,knee joint,ankle joint force,joint torque and main muscle force of human lower limb,the walking gait model of human was established by using anybody software,and the biological parameters of lower limb joint and main m-uscle during normal walking were obtained by dynamic simulation.After that,by add-ing a driver on the shin of the leg,the walking state of the human body wearing t-he knee exoskeleton is simulated.The changes of joint force,torque and main muscl-e force of the lower limb joints before and after wearing the knee exoskeleton are c-o MPared and analyzed,and the influence of the knee exoskeleton on human gait cha-racteristics is qualitatively analyzed.