Study On The Activation Mechanism Of Ankle Joint Muscle During Upright Standing Push-recovery With Disturbance

Studying the internal control mechanism of the human is crucial to human-robot interaction.In this thesis,the activation mechanism of ankle joint muscle during human upright standing push-recovery with disturbance is used as a research topic.A muscle reflex model is established by combining stretch reflex control and force feedback control.To investigate the mechanical mechanism of human muscle activation during human upright anti-disturbance,an upright standing push-recovery experiment is designed and completed.The main research work of this thesis is as follows:(1)The muscle reflex model of the ankle joint is established in the upright anti-disturbance.The human body is regarded as an inverted pendulum that rotates around the ankle joint,and the calculation formula of the ankle joint moment is derived by analyzing the human body’s upright balance.The muscle reflex model is established based on the stretch reflex model and the force feedback model.(2)Designing and building the upright standing anti-disturbance test platform.The sandbag dropped from different heights is used as the disturbance to complete multiple experimenters’ standing anti-disturbance experiments.The real-time simulator is used to collect the EMG data of tibialis anterior(TA),gastrocnemius(GAS)and soleus(SOL),human kinematics data and ankle joint dynamics data simultaneously.Analyzing the dynamic characteristics of the ankle joint by experimental results.When the human back is disturbed,the SOL and GAS are activated to adjust the ankle stiffness to resist forward tendency,and the ankle stiffness of the human body when leaning forward is bigger than the recovery segment.(3)Studying muscle activation based on stretch reflex.A parameter identification method based on particle swarm algorithm is designed,and the parameters of the stretch reflex control model are iteratively optimized through a large amount of experimental data.The analysis of the model predicted data and experimental data shows that the %VAF of the stretch reflex control model is mostly above 80%,and the model can predict the trend of muscle activation well.(4)Studying of muscle activation based on muscle reflex.The parameters of the muscle reflex control model are obtained through parameter identification,and the predicted results of the model are compared with the experimental data.The %VAF of the model is mostly over 90%.Through analyzing the data could find the stretch reflex activate muscles firstly to generate muscle force to resist disturbance when human is disturbed,and then the positive feedback of the muscle force provides stable force compensation,and adjusts the stiffness of the ankle joints to suppress the human body’s forward tendency.This thesis designs and completes an upright standing push-recovery experiment,and explores the activation mechanism of ankle joint muscle when the human body is upright disturbed.The comparative analysis of the experimental data to verify the validity of the stretch reflex control model and muscle reflex control model,and analyzes the role of stretch reflex and force feedback in muscle reflex,which can provide a reference for intelligent control design of exoskeleton and robotic joints.