Modeling And Experimental Verification Of The Integrated Muscle-tendon-exotendon System Of Human Hip Joint

Passive lower limbs exoskeletons have potential advantages in reducing metabolic energy cost of human walking and enhancing the walking endurance.The development of practical exoskeleton devices have important scientific significances and urgent practical needs.Inspired by the efficient energy conversion characteristics of human biological tendon tissues,our goal is to carry out the biomechanical modeling and experimental study of human hip joint assisted by an elastic exotendon,and to reveal the biomechanical behavior and energy conversion mechanism of the musculoskeletal system of lower limbs under exotendon assistance.The developed hip passive exoskeleton device can effectively help reducing the metabolic energy cost of walking.Our research results provide an innovative solution for the design of exoskeletons to reduce the metabolic energy cost of human walking,and provide supports for using engineering science method to enhance the movement ability of human body.The main research work includes:(1)The proposal and embedding principle of an elastic exotendon.Based on the energy storage and release characteristics of human biological tendon and its influence mechanism on metabolic energy,the bionic design principle of the human biological tendon is studied,and the embedding method of an elastic exotendon is proposed to store energy in the negative work phase of the hip joint and release energy in the positive work phase.Combined with the characteristics of hip joint power and electromyography during walking,the design scheme of the hip joint exoskeleton driven by elastic exotendon is finally determined.(2)The construction method of the hip joint musculoskeletal model.Based on the Hill-type muscle model and combined with the theory of hip joint geometry and anatomy,a simplified musculoskeletal hip biomechanical model is established for replicating the natural human walking behavior with the constraint of characteristic relationship between the muscle force,length,and contraction velocity,whose parameters are optimized by minimizing the difference between the model output torque and the biological torque of human joint,which provides the foundation for the subsequent simulation analysis.(3)The integrated simulation analysis of the muscle-tendon-exotendon.To study the influence of exotendon assistance on muscle force,muscle activation,work and metabol-ic energy consumption of each muscle,the dynamic and energetic characteristics of the hip joint muscle-tendon assisted by exotendon of different stiffness are optimized using a reverse method to minimize the total metabolic energy cost of muscles,which provides theoretical support and design basis for the hip joint exoskeleton devices.(4)The development and experimental verification of an exoskeleton prototype.According to the simulation results,a prototype of the hip passive exoskeleton is developed to carry out the walking experiment under natural gait,the experimental data of electromyographic and metabolic energy are analyzed to evaluate the assistant effects of the device on human body and verify the modeling theory in this paper.