Research And Application Of Walking Stability Of Lower Limb Exoskeleton Robot

As of 2019,the number of patients with lower limb motor dysfunction in China exceeded 85 million.At present,some patients undergo rehabilitation training for walking with exoskeleton robots of lower limbs.The existing lower exoskeleton robot has the problem of poor walking stability.Most lower limb exoskeleton robots need to be used with crutches.The use of crutches can cause inconvenience in movement and adverse psychological effects to patients with lower limb movement disorders.In order to get rid of crutches with the assistance of lower extremity exoskeleton robots and perform rehabilitation training for free walking.Aiming at the walking stability of lower exoskeleton robots.Through the establishment of kinematics and dynamics models,the analysis of walking stability,the design of stability control algorithm and its experimental verification were researched.The main research contents are as follows:(1)The kinematics and dynamics model of the lower exoskeleton robot was established.Based on the D-H method,a positive kinematics model of the lower limb exoskeleton robot was constructed to solve the trajectory curve of the end of the swinging leg.A method for constructing the inverse kinematics model of the exoskeleton robot of the lower limb was proposed by Jacobian.The advantage of this method is that it can quickly obtain the angle trajectory of each joint,and it has more real-time performance.Based on the Lagrangian method,the dynamic model of the lower extremity exoskeleton robot was established to find the relationship between the angle and torque of each joint,which provides a theoretical basis for walking stability control.Through OpenSim software simulation,the accuracy of the inverse kinematics model based on Jacobian method was verified.The torque curve of hip joint and knee joint was simulated.(2)According to the ZMP theory,a fast ZMP real-time coordinate acquisition method based on sole pressure was proposed.Furthermore,the conditions for triggering the walking of lower limb exoskeleton robot was derived.Compared with the traditional ZMP coordinate acquisition method,this method obtains ZMP coordinates at a faster speed,which improves the fluency of lower exoskeleton robot walking.Through software simulation,the five-point method was used to simulate the trajectory curve of the end of the swinging leg of the lower exoskeleton robot.(3)The fuzzy PID control strategy was introduced to improve the walking stability when the feet touch the ground.This method has achieved the purpose of walking stability by adjusting the center of gravity of the person.In view of the excessive chattering problem of traditional sliding mode,the introduction of the RBF neural network sliding mode control strategy reduces the chattering problem during walking and improves the walking stability when one foot touches the ground,thereby making the lower extremity exoskeleton robot more natural during walking.(4)Relying on the experimental platform of the lower extremity exoskeleton robot in the rehabilitation laboratory,the walking stability of the lower exoskeleton robot was experimentally verified.Experiments show that,without the aid of crutches,the lower extremity exoskeleton robot has achieved the purpose of walking stability.