Design And Performance Analysis Of Non Powered Ankle Exoskeleton Device

At present,the global aging situation is increasingly serious,and the decline of body function caused by human aging is inevitable.There are many kinds of traditional equipment to assist people with lower limb muscle weakness,although they can solve the movement problem of people with lower limb muscle weakness to some extent,they cannot provide good auxiliary effects for users,and it is difficult to guarantee the quality of life of users.In order to improve the above problems,in recent years,a series of non-powered lower limb exoskeleton robots have appeared with the purpose of reducing the metabolic energy consumption of wearers and helping with rehabilitation.According to the number of auxiliary joints,they can be divided into multi joint non-powered lower limb exoskeleton robots and single joint nonpowered lower limb exoskeleton robots.Due to the limitation of current material and human body theory,the single joint exoskeleton robot is superior to the multi joint lower limb exoskeleton robot in auxiliary effect,cost and adaptability.In terms of the selection of auxiliary joints,based on the research on the characteristics of the three joints in the lower limb walking movement,this paper chooses the ankle as the auxiliary joint of the unpowered exoskeleton robot to assist people with muscle strength decline in assisted walking.The main research contents of this paper are as follows: firstly,the relevant research results at home and abroad,the anatomy of human lower extremity joints and the gait behavior are studied.Combined with the analysis of the normal walking gait characteristics of lower extremity joints,the power assist principle of the unpowered ankle exoskeleton device is obtained.Secondly,based on the research of human motion theory and device design at home and abroad,the device model is designed by using three-dimensional drawing software,and a kind of non powered ankle exoskeleton device is processed according to the drawings,and its structure design,working principle and working process are introduced in detail.Thirdly,with the help of Open Sim human motion modeling and simulation software,the corresponding trigger conditions and stiffness coefficients are set for the model by using Thelen’s method,and the assistance effect of the non-powered ankle exoskeleton on the wearer is simulated.Fourthly,the prototype of the unpowered ankle exoskeleton is verified by two sets of performance tests.VICON motion capture system,AMTI three-dimensional dynamometer and Delsys EMG equipment are used to collect and analyze the wearer’s motion time-space parameters and EMG signals;The heart rate and metabolic energy consumption of subjects are monitored and analyzed by MASTERSCREEN CPX METABOLIC CART system.The results of simulation experiment and prototype wearing experiment showed that the prototype of non-powered ankle exoskeleton device designed in this paper had a certain assistance effect and could reduce the metabolic energy consumption of the wearer,and met the design requirements of the device.The simulation results showed that with the increase of stiffness coefficient of energy storage spring,the muscle strength and muscle work of human body showed a downward trend.When the stiffness coefficient increased by 4000 N / m,the maximum muscle strength of soleus muscle decreased by 223 N on average,and that of gastrocnemius muscle decreased by 33.2 N on average.The range of work done by soleus muscle decreased from 154.2W to 86 W,and that by gastrocnemius muscle decreased from235 W to 218.6W.The results of prototype wearing experiment showed that with the increase of stiffness coefficient of energy storage element,the peak of gastrocnemius and soleus muscle electrical signal of wearer could be reduced by 16% and 21.2%,the metabolic consumption of wearer could be reduced by 3%,and the heart rate could be reduced from 105 BPM to 99 BPM.