Design And Study Of A Quasi-zero Stiffness Isolation System For A Robot Supporting Joint

Mechanical vibration in production and life is very common,sometimes it is necessary to use mechanical vibration to improve working efficiency.However,in most cases,vibration will bring damage to human production,especially,low-frequency vibration will cause harm to human.Based on the national natural science fund “based on the energy characteristics of flexible parallel precision positioning platform vibration suppression control research” and base on the study of quasi-zero stiffness(QZS)isolator at home and abroad,a kind of quasi-zero stiffness vibration isolation system is designed for the support joints of lightweight rehabilitation robots.By means of theoretical modeling,numerical simulation analysis and experiment,the static and dynamic characteristics,and the transfer rate of the proposed quasi-zero stiffness isolation system are studied.The main research work is as follows:Firstly,the vibration isolation principle based on the positive and negative stiffness parallel,a quasi-zero stiffness isolator is designed by combining as negative stiffness horizontal spring in parallel with a positive stiffness linear coil spring.Through the statics study of zero stiffness isolation,the theoretical differential equation of the vibration isolation system is obtained,and the static equilibrium position of the system and the quality of the vibration isolation object are further obtained by the isolation system parameters.Secondly,the dynamic equations of the QZS vibration isolation system under harmonic force and displacement excitations are established.The Taylor expansion and harmonic balance method is used to simplify and deduce the nonlinear differential equations,and the transfer rate of quasi-zero stiffness isolation system is obtained,which is compared with the linear system.Then,the parameters that affect the transmission rate,such as the excitation amplitude,damping ratio and stiffness ratio,are analyzed,which change on the vibration isolation performance of the whole system is analyzed.Again,The MATLAB software is used to simulate the quasi-zero stiffness and linear system,and the simulation results are compared with the experimental results,which shows the excellent performance of the quasi-zero stiffness low frequency vibration isolation.Finally,according to the results of theoretical calculation and software simulationanalysis,the structure of the vibration isolation system is optimized and the final size is determined,and the experimental prototype is processed.The experimental platform of the quasi-zero stiffness isolation system is built,the displacement transfer rate of the vibration isolation system is obtained by using the upper computer and the laser displacement measuring device.the measurement of the linear system is carried out,when the external condition is stable.The performance of the quasi-zero stiffness low frequency vibration isolation is verified by comparing the measured data with the simulation.