Study On The Squat Support Performance Of Flexible Lower Extremity Exoskeleton

Nurses,doctors,and workers in the assembly line,because they stand for a long time,do not get rest in their legs,often feel sore body,which can easily lead to swelling of the lower extremities and varicose veins.For workers who stand for a long time,as the working hours increase,the discomfort of the legs will gradually reduce the work efficiency.There is limited space in the operating room and production line,and it is not possible to provide workers with a chair to sit and rest.This project aims to design a flexible lower extremity exoskeleton,which is worn on the legs of the human body.It uses the flexible drive of the human body to break through the rigid structure to limit the movement of the wearer.When the wearer squats,the leg support of the flexible lower extremity exoskeleton can form a stable chair,allowing the wearer to sit down and rest,reducing the fatigue of the leg muscles.The main content of this article:First,analyzing the structure and freedom of the lower limbs of the human body,it is determined that the hip joint has 3 degrees of freedom,the knee joint has 1 degree of freedom,and the ankle joint has 3 degrees of freedom.The human body squat experiment is carried out.The height of the subjects ranges from 1580mm to 1840mm,and the weight ranges from 52.2kg to 96.1kg.Getting the relevant size of the lower limbs of the human body,including thigh circumference,calf circumference,waist circumference,thigh length,and calf length.The experimental data of human squatting is calculated,and the angle of the knee joint ranges from 113.05° to 148.97° when the subject reaches the squat comfort state.The distance between the posterior point of the ankle joint and the posterior side of the hip joint ranges form 482mm to 572mm.Secondly,using the theory of metamorphic mechanism and folding mechanism,three design schemes of flexible lower extremity exoskeleton are proposed.Through the multi-factor fuzzy evaluation method,the optimal flexible lower extremity exoskeleton design scheme is obtained.The structural diagram of the flexible lower extremity exoskeleton is drawn,and the optimal structure of the flexible lower extremity exoskeleton is determined through optimization and improvement of the design scheme.Thirdly,using Creo2.0 software to establish a three-dimensional model of flexible lower extremity exoskeleton,using Creo software to establish three-dimensional human body,set the constraint relationship between human body and flexible lower extremity exoskeleton,and establish a coupling model of human body wearing flexible lower extremity exoskeleton.Import to ADAMS software,the physical characteristics and constraint relationship of the flexible lower extremity exoskeleton are set,and the dynamic simulation of the flexible lower extremity exoskeleton is carried out.The resultant force of the thigh rod reaches the maximum value of 6.65N at the initial state,and the resultant force of the support rod reaches the maximum value of 2.43N at 5s.The resultant force of the support sleeve reaches the maximum value of 3.74N at 5s.Finally,the ANSYS software is used to perform finite element analysis on the dangerous members of the flexible lower extremity exoskeleton,and the deformation and stress diagrams of the support rod and the support sleeve are output.The analysis results show that the maximum deformation of the support rod is 1.11mm,the maximum stress is 184.04MPa.The maximum deformation of the support sleeve is 0.32mm,and the maximum stress is 49.99Mpa.The material of the flexible lower extremity exoskeleton is 7050-T7651 aluminum alloy,and the allowable stress is 312.5 MPa.The maximum stress is less than the allowable stress to meet the design requirements.The research on the squat support performance of the flexible lower extremity exoskeleton allows the wearer to sit and rest at any time.It will improve the wearer's work efficiency,relieve leg fatigue caused by long-term standing,prevent varicose veins,reduce swelling of lower limbs,and reduce related complications.It has important scientific significance,social value and application prospects.