Design And Experimental Study Of Lower Limb Unpowered Assistance And Energy Harvesting Exoskeleton

The lower limb assistance and energy capture device is used to reduce energy metabolism during human movement,and on the other hand,it collects and converts the energy generated during lower limb walking for the power supply of small and micro.devices.This article focuses on the innovative design of mechanisms,simulation analysis,and functional and performance experimental testing of lower limb unpowered assistance and energy harvesting exoskeletons.The main contents are as follows:(1)Analysis of biomechanical characteristics of lower limb movements.According to the gait law of the lower limb,it is simplified to a planar three link structure,and a biomechanical model of the lower limb is established using the Lagrange equation method.The gait data of the lower limbs were collected using the optical dynamic capture experiment method,and processed and integrated using Mokka software and Origin software.Relying on the programming function of MATLAB software,the parameters such as joint angle,dynamic potential energy,joint moment of force,and work performed during walking of the human lower limbs were calculated and analyzed on the basis of the gait cycle theory.(2)Design of unpowered assistance and energy harvesting exoskeleton system.Based on the analysis results of gait characteristics and dynamic parameters,and based on the principles of unpowered power assist and piezoelectric energy capture,a lightweight lower limb assist energy capture exoskeleton with a flexible traction rope and a lightweight mechanism box was designed.Two design schemes are proposed for different installation methods of power assist components and energy capture components,and the final scheme of power assist and energy storage module is designed in detail.At the same time,the key components in the design are checked using computational verification and finite element simulation analysis to verify the accuracy of the scheme design.(3)Simulation analysis of coordination between lower limb assistance and energy capture exoskeleton wearing.Using Adams software to simulate the process of the cam impacting the piezoelectric sheet,the rationality of the device is verified through the positive and negative rotation speed,deformation angle,and stress of the cam;At the same time,the simulation and analysis of the lower limb movement process and the degree of human-machine coupling were conducted,and the dynamic parameters of each joint of the lower limb before and after wearing were output to verify the rationality of the biomechanical model and the human-machine coordination of the device;Using Opensim software,add an equivalent spring with the same effect as the assist component,and simulate the total metabolism of the lower limbs and muscle metabolism of each part under the designed input tensile force,to verify the effectiveness of the designed assist function of the exoskeleton.(4)Experiment and Analysis of Exoskeleton Function and Performance.Use the Vicon optical motion capture system to collect gait data before and after wearing the exoskeleton,and after processing,compare and analyze the changes in dynamic parameters and the amount of work done before and after wearing,to verify the assistance effect of the device;Connect a piezoelectric piece to an oscilloscope and conduct a piezoelectric energy conversion test after wearing the device to obtain the corresponding voltage;The power of the four piezoelectric chips in parallel is calculated through an external rectifier circuit,and the number and frequency of light-emitting diodes that can be lit in this energy trapping state are used to verify the energy trapping effect of the device.The research results of this article provide an effective solution for assisting and capturing energy conversion methods,and also provide theoretical and practical reference for the same type of research page.