Research On Wearable Knee Force Feedback Exoskeleton Assist System

Exoskeletons in nature represent hard shells that protect soft tissues and organs inside animals and plants.The exoskeletons studied in this paper are metal moving devices that provide power-assisting torque to the knee joints of human legs.Exoskeletons can work for a long time like robots or help the human body lift objects several times heavier than themselves,so they are widely used in medical rehabilitation,military operations and industrial manufacturing.This paper studies and analyzes the movement of the human body under the gait such as walking on a flat road,going up the stairs,going down the stairs and squatting in place,and then establishes a control model using negative feedback closed-loop control and mature PID algorithm,and uses ADAMS simulation software and The simulink toolbox of MATLAB software to carry out the simulation test of joint motion,and finally developed a knee joint exoskeleton device that can provide power-assisting torque.The main research items and results in this paper are as follows:In this paper,the mechanical structure of knee exoskeleton device is designed.By analyzing the degrees of freedom of the knee joint of the human leg and the range of motion of the knee joint,the relevant parameters of the exoskeleton mechanical structure design are obtained.The knee exoskeleton adopts an anthropomorphic design method based on the analysis of the physiological structure and motion characteristics of the human knee joint,so that the exoskeleton has a good match with the motion of the human leg.Considering that the human body needs to move in a variety of gaits after wearing the exoskeleton,the overall weight and size of the exoskeleton should be minimized.The knee joint exoskeleton is driven by a maxon DC motor,and is decelerated by a harmonic reducer to provide an appropriate boost torque for the human leg.This paper studies and judges the control algorithm of human motion intention.The stability of the exoskeleton detection and control system is the key to ensure that the exoskeleton provides the expected amount of assistance.The knee exoskeleton designed in this paper detects the angular velocity of the relative rotation of the upper and lower legs through the gyroscope,that is,the accelerometer,and then detects the pressure between the legs and the exoskeleton link.Through the combined analysis of the pressure and angular velocity signals,we can judge and predict the movement state of the person wearing the exoskeleton.In this paper,the motion model is established and the joint simulation of ADAMS and MATLAB / Simulink is carried out.After analyzing the weight distribution of the lower and upper limbs of the human body,the anthropomorphic design method was used to establish the three-dimensional motion model of the human body and the exoskeleton,and then the driving functions,kinematic pairs,forces and other parameters were set in the ADAMS simulation software.By simulating and analyzing the motion process of the human model’s gait,such as going up the stairs,going down the stairs,walking on a flat road and squatting in place,the change curve of the motion parameters of the knee joint is obtained.The mathematical model of the exoskeleton control system is built in the MATLAB software,and then the motion model in the ADAMS software is imported into the MATLAB software for joint motion simulation.Exoskeleton wearing test is carried out in this paper.The hardware processing and installation of the designed exoskeleton device is completed,and then the human body wears the exoskeleton device for walking motion.Based on the analysis of the data signals detected by the sensors during the movement process,the follow-up effect and boosting effect of the knee joint exoskeleton device are tested.