Design And Experimental Study Of Passive Hip Assisted Exoskeleton

The hip joint is one of the most important joints in human movement.It is responsible for starting the lower limbs while connecting the upper body.Power assisted exoskeleton is a kind of auxiliary walking equipment that can enhance the walking endurance of human body or reduce the metabolic cost of human body.It can recover the mechanical energy of human body and convert the mechanical energy into elastic potential energy through its mechanical structure to complete the assistance for human walking,so as to reduce the metabolic cost of human body in the process of walking and improve the threshold of human walking.In this paper,the current status of non-powered helper-assisted exoskeleton at home and abroad,mainly based on the hip joint,was analyzed.Combined with the motion characteristics of human lower limbs and the anatomy of hip joint,a combined non-powered hip helper-assisted exoskeleton with variable stiffness spring and coil spring as energy storage elements was designed.(1)Analysis of human lower extremity characteristics and establishment of mathematical model.y studying the biomechanical characteristics of lower limb movement and hip anatomy,the inverse kinematics model and inverse dynamics model of lower limb are established,Through the lower limb data acquisition experiment on human body,the movement trajectories of the torso and foot parts were obtained.The data collected according to the gait were imported into the inverse dynamics and inverse kinematics model of human lower limb to obtain the passive hip joint assisted exoskeleton design input--hip joint motion parameters.(2)Design of non-dynamic hip exoskeleton.By analyzing the walking gait cycle of human lower limbs and the motion law of hip joint,the adaptive motion principle of the device was obtained.The design parameters of variable stiffness spring and coil spring were determined according to the motion parameters of hip joint.The rationality of the design of energy storage element was verified by ANSYS simulation.According to the motion stroke of the variable stiffness spring,the CAM transmission mechanism and the fixed structure of the variable stiffness spring are designed;Binding connection structure is designed according to ergonomics.Finally,the physical processing of the exoskeleton is carried out to verify the rationality of the exoskeleton mechanism design,mechanical structure transmission and man-machine collaboration.(3)The man-machine coupling simulation.Adams and Solidworks were used to build a human-human coupling model between human body and exoskeleton,and man-machine collaboration and exoskeleton booster effect were analyzed in ADAMS.The man-machine motion collaboration was verified by comparing the angular velocity,thigh center-of-mass velocity and calf center-of-mass velocity before and after the human body model wore the exoskeleton.The hip joint torque before and after the human model wearing the exoskeleton was compared to verify the rationality of the exoskeleton design and the effect of assisting.(4)Experiment to verify the effect of help.Through Nokov motion capture experiment,the changes of hip Angle,torque,kinetic energy and potential energy before and after wearing exoskeleton were obtained.Through the electromyographic experiment,the changes of electromyographic signals of human rectus femoris,femoris lateralis and tibialis anterior muscle before and after wearing the exoskeleton were obtained,and the assisting effect of the device was analyzed and verified.