| Space antenna is a key component for communication and data transmission in spacecraft.It is a high flexibility and low damping structure.In the process of antenna attitude adjustment,the disturbance generated by the rotation unit is transmitted through the antenna structure and finally acts on the spacecraft body.If this disturbance is too large or coupled with the motion of the spacecraft,it will have a serious impact on the pointing accuracy and operational stability of the antenna,which will affect the on-orbit performance of the spacecraft.In this paper,a biaxial directional antenna is taken as the research object.Through the combination of dynamic simulation analysis and ground disturbance experiment,the disturbance characteristics of the antenna structure are analyzed and discussed,which provides technical support for the micro-vibration optimization design of the biaxial directional antenna.Firstly,the disturbance experiment of the main disturbance source(rotating unit)of the antenna is carried out.Then,the inherent characteristics of the antenna structure under different attitudes are analyzed by finite element method.Finally,based on the test results of the rotation unit,the transient dynamic response analysis of the antenna structure under typical working conditions is carried out,and the correctness of the analysis method is verified by the antenna ground disturbance test experiment.The main research work is as follows :Firstly,aiming at the rotating unit composed of permanent magnet synchronous motor and harmonic reducer,a rotating unit disturbance test device is established,and the disturbance test of the X-axis rotating unit and the Y-axis rotating unit of the antenna is carried out respectively.The disturbance force and disturbance torque of the output end of the harmonic reducer at the typical working speed of the X-axis and Y-axis rotating units are obtained.The characteristics of disturbance force and disturbance torque and the influence of working speed and load on the disturbance of the rotating unit are analyzed from two aspects of time domain and frequency domain.Secondly,based on the physical structure of the antenna,combined with the material parameters of each component,the finite element analysis model of the antenna is established,and the modal characteristics of the antenna structure are analyzed.The first 8-order natural frequencies and modal shapes of the antenna under three typical attitudes during the attitude adjustment process are discussed.The results show that the attitude of the antenna has little effect on its natural frequency,but has a certain influence on the modal shape.Under three typical attitudes,the first 5-order natural frequencies of the antenna structure are small,reflecting the typical flexible body characteristics of the antenna.The modal shapes of the antenna show a bending shape similar to that of the cantilever beam.Finally,based on the finite element analysis model of the antenna structure,the dynamic analysis model of the antenna multi-flexible body system is established based on ADAMS software.The transient dynamic response analysis of the antenna structure is carried out with the disturbance test results of the rotating unit as the driving condition,and the disturbance force and disturbance torque of the antenna structure under typical driving mode and speed are discussed.The reliability of the dynamic analysis model is verified by the antenna ground disturbance test experiment.The results show that the disturbance force and disturbance torque of the antenna structure are mainly concentrated in the low frequency band.Compared with the single-axis drive mode,the disturbance of the antenna is more intense in the dual-axis drive mode.Different from the driving mode,the driving speed has little effect on the disturbance of the antenna. |
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