基于耦合摆模型的人体行走能耗分析

Analysis of the energy cost of human walking based on a coupled pendulum model

基于人体行走摆动相期间摆动腿相关肌肉群几乎静息的现象,本文提出一个耦合摆模型并建立人体行走摆动相和双支撑相数学模型.采用打靶法求解摆动相期间支撑腿踝关节、摆动腿髋关节和膝关节角度变化.基于动量守恒计算摆动腿膝关节锁定和脚跟着地时,各关节角速度的变化,得出能量损耗率.分析各关节存在摩擦力矩时对摆动腿膝关节锁定和脚跟着地能耗率的影响.在髋关节与踝关节分别引入弹性储能元件,分析其对行走步态与能耗的影响.研究结果表明,基于数学模型计算出的各关节角度随时间的变化与正常行走时的实测数据非常接近;行走过程中主要的机械能损耗源于脚跟着地撞击,其能耗远大于膝关节锁定和摩擦力矩引起的能耗;在髋关节处添加弹性储能元件会缩短摆动腿摆动相时间,使步速加快,但导致脚跟着地时的能耗上升;在支撑腿踝关节处添加弹性储能元件可以降低摆动腿脚跟着地的能耗,并不会影响步速.本文的研究结果可为下肢助力外骨骼和足部假肢的设计与研究提供参考依据.

Based on the phenomenon wherein the muscle groups of the swing leg are nearly quiescent during the swing phase of human walking,a coupled pendulum model is developed to formulate mathematical models of the swing and double-support phases of human walking.The shooting method is used to determine the ankle angle of the stance leg,hip angle,and knee angle of the swing leg.Changes in joint angular velocities during knee-lock and heel-strike are calculated using the principle of momentum conservation,and the rate of energy cost is obtained.The effects of joint frictional torque on the rates of energy cost during knee-lock and heel-strike are also analyzed.Joint elastic components are added to the hip and ankle separately,and their effects on walking gait and energy cost are assessed.Results indicate that the joint angles computed using the mathematical models are very close to the experimental data collected during normal walking.Most of the mechanical energy loss during walking results from the impact at heel strike,which is greater than the energy loss resulting from knee-lock and frictional torque.Elastic components added to the hip can reduce the time of the swing phase,which enables faster walking at the cost of higher energy at heel strike.Elastic components added to the ankle of the stance leg can reduce the energy cost during the heel strike of the swinging leg but does not affect pace.These results provide a reference for the research and design of lower limb exoskeletons and foot prostheses.