Design Of A Soft Exosuit For Assisting Daily Walking Of The Elderly

Due to decrease of muscle power,the elderly lose some walking ability,leading to inconvenient daily walking.Soft exosuits are suitable for assisting the elderly walking,because they are light and compatible to human.But for some reasons,soft exosuits are still unable to facilitate daily walking of the elderly.First,most existing soft exosuits assist level walking only,incapable of assisting daily walking with multiple walking environments.Second,previous exosuits add too many straps to human body,which may not be accepted by the elderly.Third,actuators of previous exosuits are heavy,not suitable for daily use.In order to adapt the soft exosuit to assist daily walking,it is urgent to improve the design of exosuit,reduce the weight of actuator and find a control method capable of assisting different walking environments.This paper comes from an NSFC: an in-wear exosuit for assisting the elderly walking.The paper aims to develop a soft exouist for assisting daily walking of the elderly.The main research work of the paper is as follows:(1)Analysis of lower limbs biomechanics for multiple walking environments was performed.Whatever it is level walking,stair walking or slope walking,ankle push-off work holds a big proportion of COM work,especially during level walking,ankle pushoff work accounts for more than 50% of total COM work.Considering the probability of level walking is biggest in daily walking,assisting ankle joint will benefit most.(2)A soft exosuit totally integrated to shoe was designed.The wear parts of proposed exosuit were completely integrated to shoe,with no other part add to human body,which may reduce the wearing complexity and increase acceptability of the elderly.A light portable actuator was designed.The actuator utilized positive and negative rotation of one motor to actuate bilateral legs,in this way the number of required motor and control devices is reduced.The weight of actuator is only 2.45 Kg,lighter than any other ankle assistant soft exosuits we known.(4)A force-based position control was performed to generate required assistant power.The force-based position control transforms the complicated force control problem to a simple position control of the motor by the means of exosuit stiff model.Based on the above researches,experiments in three different walking environments were performed to compare the assisting effect of proposed exosuit.Preliminary results demonstrated the effectiveness of proposed exosuit to reduce the requirement of ankle muscle activations.