Design Method And Experimental Study Of Lower Limb Unpowered Exoskeleton For Reducing The Metabolic Energy Of Human Locomotion

It has been a hot topic that augmenting human locomotion ability with engineering science methods in the field of wearable lower limb robotic exoskeletons.However,there are fundamental differences in the kinematics and biomechanics of human lower limbs during walking and running.How to design unpowered exoskeleton to reduce the metabolic energy of walking and running simultaneously is still a challenging problem.Based on the analysis and summary of domestic and foreign lower-limb exoskeleton research,a systematic research is conducted on this challenging problem,from the aspects of passive assistance principle of regulating the human lower limb joint power,the design method of unpowered lower limb exoskeleton and the law of metabolic consumption and biomechanical change during human-exoskeleton interaction.The main innovative results of the dissertation are as follows:1.Through quantitative analysis of human lower limb kinematics,joint mechanics and joint power at common walking and running speeds in the human daily life,the differences in lower limb kinematics and biomechanics as well as common biomechanical laws between walking and running are revealed.And we find the main work periods and common energy consumption characteristics of knee and hip muscle groups in walking and running.The functional characteristics of lower-limb tendons and bi-articular muscles to reduce the metabolic energy of locomotion are analyzed to provide a guiding basis for proposed design methods of unpowered exoskeleton in the subsequent chapters.2.To address the problem of how to reduce the metabolic energy of walking,the passive assistance principle of regulating the hip and knee power in different gait phase is proposed,based on the energy consumption law of knee and hip joints in walking gait.The design method of hip-knee unpowered exoskeleton based on mechanical clutch-spring mechanism is established.The human-exoskeleton interaction experiment of walking with exoskeleton is carried out,and the spring stiffness is optimized through the experiment.The experimental results show that the walking(1.5 m/s)metabolic rate is reduced by 8.6% ±1.5% in the optimal spring stiffness condition(k = 270 Nm/Rad)relative to walking without the exoskeleton.The energy saving effect is improved by 19.4% compared with the most advanced unpowered exoskeleton.3.The passive assistance principle of regulating the hip flexion energy is proposed to simultaneously reduce the metabolic rate of both walking and running based on the common energy consumption characteristics of the hip musculature between the two gaits.In the common optimal spring stiffness condition for both walking and running(k = 83 Nm/Rad),the metabolic rates of walking and running are reduced by 7.2% ± 1.2% and 6.8% ± 1.0%,respectively,compared to walking and running without the exoskeleton.The metabolic rate is reduced within the tested range of walking and running speeds(except for low-speed walking).The energy saving effect of the proposed exoskeleton is increased by 41%compared with the most advanced fully autonomous hip powered exoskeleton.4.To address the scientific problem of how to regulate the energy of multiple lowerlimb joints during both walking and running,the passive assistance principle of regulating hip and knee power in different gait phase during both walking and running is proposed,inspired by the double actuation and energy transfer function of biarticular muscles.The design method of hip-knee unpowered exoskeleton based on biarticular exotendon is established to enhance the energy recycling and transfer function of multiple biarticular muscle groups in different gait phases.The experimental results show that the metabolic rate of walking and running with the assistance of the exoskeleton decreases by 6.2 ± 1.2%and 4.0 ± 1.0%,respectively,compared to walking and running without the exoskeleton.