Study On Working Principle And Dynamic Characteristics Of Unpowered Lower Extremity Exoskeleton

The exoskeleton is a wearable robot that is mainly human-oriented and supplemented by machinery.It not only has the functions of protecting the human body and supporting the human body structure,but also enhances the body’s athletic ability.Exoskeletons have been widely used in military,civilian,medical and other fields.Most of the current exoskeleton research focuses on active exoskeletons,and there are relatively few studies on unpowered exoskeletons.Compared with the active exoskeleton,the unpowered exoskeleton removes the external energy source and its driving device,reduces the volume and weight of the overall structure,improves the flexibility of the system,enhances the coupling between the human and the machine,and improves the human body.This paper studies the working mechanism and dynamics of a unpowered lower extremity exoskeleton based on clutch and tension spring.The research results can provide reference for further research on unpowered exoskeleton.The main work done is as follows:(1)The musculoskeletal model of the lower limbs of the human body was established in the Anybody software.The model was driven by thee three-dimensional coordinates of the lower limb motion control points and the ground-supporting force.Through the inverse dynamics analysis of the model,the curve of the joint angle,joint torque,muscle strength change were obtained,as well as changes of muscle work power and muscle metabolic rate.(2)By discussing the kinetic energy changes of the human body’s centroid,the effects of the heel and helium energy storage,the impact loss of the foot and the ground on the human metabolic energy were analyzed.The structure of the unpowered lower extremity exoskeleton based on clutch and tension spring is analyzed.It is clarified that the exoskeleton can share the strength of the calf muscle,reduce the collision loss between the foot and the ground,and thus reduce the metabolic energy of human gait.The principle of can help to achieve the purpose of assisting.(3)The bio-mechanical model of human wearing exoskeleton was established.The variation of the ankle joint driving torque and the work done by the calf muscle on the ankle joint were studied.The exoskeleton can share the power of the calf muscle during walking to reduce metabolic energy.