Research On Multi-Dimensional Disturbance Dynamic Testing Technology

The form of micro-vibration is complex,with small amplitude,wide frequency distribution and multi-directional vibration.In the development of space remote sensing satellites,micro-vibration is an important factor affecting the key performance of pointing accuracy and camera imaging quality.In order to predict the effect of disturbance on the spacecraft and take corresponding vibration suppression measures,accurate acquisition of the disturbance data of the vibration source is the most important guarantee for the study of spatial on-orbit micro-vibration.At the same time,with the development of large-scale space telescopes,the mass of vibration source is getting larger and larger,and the output disturbance is more and more complicated.The existing micro-vibration test conditions for vibration source have been difficult to meet this kind of development needs.Therefore,research on related micro-vibration testing techniques and vibration source analysis and other key technologies is of great significance for the development of space telescopes.In this paper,the observation theory of micro-vibration is studied.The specific influence of sensor distribution on the test accuracy is analyzed.The measurement platform prototypes of different sensor layouts are designed to verify the theoretical model.The redundant layout method based on the eight-sensor non-codirectional parallel type is determined.The analysis shows that this layout can effectively improve the stiffness and load capacity of the platform,also take into account the advantages of the four-point parallel type,which could reduce random error and the amount of calculation.In order to solve the rigid-flexible coupling characteristics in the observation process,the vibration source disturbance transfer model is established by the generalized inverse method and the mechanical impedance principle.The generalized inverse transfer model expresses the coupling characteristics by coupling matrix,and the coupled transfer model can represent coupling matrix as a function of the frequency response characteristics of vibration sources and installation structure,and then perform decoupling analysis.The parameters of the vibration source are identified by the test prototype of the eight-component measurement platform,and then two different modeling methods are verified by experiment.The experimental results are compared with the analytical values,and different modeling methods can accurately simulate the frequency distribution of the coupled disturbance characteristics of vibration sources and elastic structure.The coupling transfer model has higher accuracy in predicting the disturbance amplitude.For the relative error of the working frequency band of the general vibration sources,it can be within 15%.According to the analysis results of micro-vibration observation theory,the force-measuring platform prototypes with strain type and piezoelectric type are designed and assembled.Through the investigation,theoretical analysis and mechanical test,the piezoelectric type is established as the core multi-dimensional force platform prototype.The configuration of the sensor was designed and tested according to the load capacity and precision.The stiffness of the platform was analyzed by finite element simulation.Considering the wide-frequency characteristics of micro-vibration,a dynamic frequency domain calibration method based on FFT is introduced.The structural coupling of the vibration source is introduced into the calibration matrix,and the static and dynamic calibration of the platform is completed by different calibration systems.Finally,a series of experiments were carried out to test the static and dynamic mechanical properties of the platform.The test results show that the resolution of force and torque can reach 0.001 N / 0.0001 Nm.In the test range of 0-800 Hz,the dynamic linearity is within 0.1% FS,and the dynamic test error is mostly within 5%.Static test error Within 5%,within the test range of 40 kN,the test linearity of the six-dimensional generalized force is within 0.1% FS and the repeatability is within 0.1% FS.Momentum wheel assembly(MWA)is a typical high-speed rotating component.During providing the necessary control torque MWA could also cause disturbance inevitably,which affects the imaging quality.Based on the multi-dimensional vibration force measurement technology of spatial micro-vibration,this paper systematically analyzes the vibration-damping mechanism of MWA,and the disturbance measurement technology under different stiffness installation conditions is developed.The platforms detected and analyzed the disturbance force of WMA under different stiffness installation conditions.Based on the test data and the classic disturbance model of MWA,an improved is proposed to more accurately reflect the disturbance characteristics under different stiffness installation conditions.