Effects Of The Flywheel Micro-vibration On The Image Quality Of A Integration Satellite

With the development of the resolution index of the remote satellite,ensured the image quality of the space camera,satellites need high pointing accuracy and stability.Most of spacecrafts have micro-vibration sources,such as such as motion of the moving components of the satellite(for example the reaction flywheel rotation and control moment gyros),step movement of the large controllable driving mechanism,propulsion jet in changing orbit and attitude,cold and hot changing of the large soft structure moving in and out of the shade which can cause jitter to the satellite called micro-vibration.It has low amplitude and high frequency,does not affect common spacecrafts,and can be ignored.However it can affect the pointing accuracy,stability and resolution for high precise resolution optical satellite.Therefore micro-vibration is being to receive more attention and researched.The dynamic environment of micro-vibration for satellite is complicated and hard to realized,and it can not be tested by the attitude control system,thus we just did partial experiment on ground to simulate the environment of outer space.We use theory model and simulation to research the displacement,acceleration and frequency of micro-vibration,to evaluate,limit and isolate micro-vibration.Therefore the paper researched a satellite and talked about the effects of the flywheel mico-vibration on on image quality.We analysed the relation between the stability of the micro-vibration,satellite structure,camera and the quality of image,by contrast of the image and key index in different cases.They can be used in satellite structure design and be prepared for optimization of satellite damping and structure.The guideline of this work is following:1.We first analyze the factors affecting image,and the methods to evaluate the image.We decided to use modulate transfer function(MTF)to evaluate the image.We discussed the effects of micro-vibration on satellite MTF.2.We researched the mathematical model of the source of micro-vibration and the effects of flywheel micro-vibration on MTF using integrated model.The flywheel disturbance was considered as simple harmonic vibration,and ray trace method was used in the simulation.The effects of the forces and moments in six directions on image was received respec tively.We can obtain the relationship between micro-vibration and MTF.3.We built up experiment to test the angular displacement of the second mirror.We designed a rubber shock absorber at the beginning,and optimized it.The data used for analysis were gotten by contrast the cases with and without rubber shock absorbers.The result was good to prove the effects of micro-vibration on angular displacements without rubber shock absorber,and the good result of vibration reduction with the rubber shock absorber under the same flywheel in the experiment.4.Then the experiment to test the effects on image quality of the flywheel under the same working cases was developed.The experiment simulate the real environment of the orbit and measured the actual effects of the flywheel.It can be verified the correctness and rationality o f the simulation model using ray tracing by contrast the results in integrated model and experiment.