Research On Lower-Limb Exoskeleton For Walking Assistance By Using Energy Harvesting

In recent years,many researchers have designed exoskeletons to assist human walking.However,most of these assistant devices need to be powered by energy supply system,such as batteries,and they would stop working once the energy resources is running out.To address this issue,some researchers have proposed methods of environmental energy harvesting to power exoskeletons,such as light and wind flow,but few of these methods is feasible due to limited power generation and instability of power source.Based on the study of human motion features,researchers have found that human walking is a periodic motion and human body energy is unevenly distributed over the cycle.It is possible to assist human walking by altering the time and space distribution of human body energy.In this work,human motion features and human energy harvesting methods were analyzed with the purpose of designing unpowered lower-limb exoskeletons for walking assistance.Two knee-based walking assist devices were proposed in this work.Before designing lower-limb walking assist devices,we first analyzed motion features and biomechanical model of human walking and then built the mathematical models of walking assistance and energy harvesting based on the analytical theories.And concrete methods of designing lower-limb walking assist system were summarized later.The knee-based walking assist device was designed based on the abovementioned analytical models and methods,followed by another lower-limb walking assist exoskeleton which was is an improved version.In order to validate the theoretical analysis,prototypes of the two walking assist devices were fabricated and tested.The experiments showed that both the knee-based walking assist device and the lower-limb walking assist exoskeleton could achieve the goal of walking assistance by reduce the metabolic cost,and extra electrical power was generated by harvesting part of the kinetic energy of human walking.The knee-based walking assist device and the lower-limb walking assist exoskeleton reduced the metabolic cost of human body by 3.62% and 3.12%,respectively;and the maximum electrical power output were 5.8W and 6.47 W,respectively.