Analysis Of Vibration Response Of Large Umbrella Antenna And Its Influence On Pointing Accuracy

With the development of satellite communication technology,countries not only use satellites for military,economic and scientific culture,but also apply satellites to space positioning and navigation,which has brought great convenience to human life.In today’s international situation,satellite positioning and navigation technology has become a measure of the development of a country’s spatial information technology,and a necessary condition for a country to seize the opportunities in future space strategy.One of the key indicators for the evaluation of satellite positioning systems is the accuracy of satellite antennas.Related studies have shown that the vibration of the antenna structure has a significant impact on the accuracy of the antenna.In some applications,the multi-body dynamics problem of the antenna and the stability of the antenna must be studied.Therefore,the research content of this paper is of great significance for the process modeling and structural design of large umbrella antennas,multi-body dynamics response analysis and pointing accuracy calculation and analysis.The main research object of this paper is the large satellite umbrella antenna.This paper first studies how to establish a whole star model based on ABAQUS secondary development,and studies the parts that can be parameterized in the whole star structure,and determines the number of antenna ribs,the number of star body compartments,and the form of solar-plate etc.Based on this,a variety of antenna models in the form of antenna ribs were built.Secondly,this paper analyzes the modal analysis and the dynamic response analysis of the whole-star finite element model obtained by parametric modeling.A zero-mean unit variance excitation is added as an input to the CMG(control torque gyro)on the antenna,and the deformation response of the antenna is taken as an output.The output deformation result is introduced into the pointing accuracy calculation part for establishing the pointing accuracy calculation model of the antenna.Finally,various factors that may have an impact on antenna pointing accuracyhave been discussed.Firstly,the definition and calculation method of antenna pointing accuracy are determined and discussed.With CMG as the disturbance source,the influence of the three factors of antenna rib number,CMG loading location and antenna cable stiffness on antenna pointing accuracy is analyzed.Finally,the distribution law of the pointing accuracy of this type of umbrella antenna under CMG excitation is obtained.The result can be used as a reference for the control and optimization of the umbrella antenna disturbance.The following conclusions are drawn by the above research: For large umbrella antennas,parametric modeling is necessary for model correction and engineering applications.Parametric modeling can be used to quickly define the geometry and material parameters to complete the model correction.For modal analysis and multi-body dynamic response analysis,the natural frequency characteristics and antenna deformation response of each part are obtained,which can be used for subsequent calculation of pointing precision parameters.Pointing accuracy response for various structures is calculated and the pointing accuracy law under the zero mean unit variance load is obtained.The obtained rule can be used for optimization and control of large umbrella antennas,so it has certain theoretical research and engineering application value.