Dynamics Design Of Stewart Platform Based On Electromagnetism Drive And Liquid Viscous Damping

With the development of the aerospace equipment towards high-precision,high-resolution and high-stability,the increasingly harsh requirements on the environment of on-orbit micro-vibration environment have been raised.The micro-vibration caused by moving parts is an important factor affecting the resolution of the payload when satellite is in orbit.It is necessary to attenuate micro-vibration in order to ensure the imaging quality of sensitive payload.This paper has studied on the Stewart platform based on electromagnetism drive and viscous damping which combining active and passive micro-vibration isolation.Firstly,a type of Stewart platform combining active and passive micro-vibration isolation on cubic structure was designed.At the same time,each part of the platform was designed and built in 3D models.Then the kinematics and dynamics characteristics were analyzed which using Newton-Euler method to establish the dynamics equations of Stewart platform.Secondly,The dynamic equations were numerically solved and the time and frequency domain characteristics of the Stewart platform under base excitation were analyzed.We used software to establish the model of vibration isolation platform.Afterwards,the influence of the structural parameters of the micro-vibration suppression platform on the dynamic characteristics of the system and the vibration isolation performance have been studied.Next,aiming at the micro-vibration in low frequency which cannot be suppressed by passive vibration isolation,the part of active control in Stewart platform was designed.Fuzzy PID control was studied to control the active vibration isolation and self-adaption could change the parameters to answer change of vibration.In addition,the results of simulation verified the validity of the method which combined active and passive vibration isolation.It can suppress the vibration in low frequency and reach the suppression in a wide spectrum band.Moreover,we developed the simulation model of Stewart platform by using the Sim Mechanics in Matlab,which could transform the Simulink models into visual views and utilize visualization to comprehend movement of Stewart platform.Finally,ground experiments of isolation tests were conducted for Stewart passive isolation platform which based on liquid damping ioslator with three parameters.What’s more,model tests and on-orbit isolation tests of the Stewart passive isolation platform were conducted.And tests results validate that the liquid damping isolator with three parameters designed by this paper possess great availability and the significance of practical application.