Research On Parameter Compensation Algorithm Of Flywheel Micro-vibration And Whole-satellite Coupling Characteristic

The flywheel is a rotating part that adjusts the attitude of the satellite on the satellite.The dynamic and static imbalance of the internal rotor and the micro-vibration caused by the bearing manufacturing and installation errors will affect the load pointing accuracy of the high-resolution optical remote sensing satellite and reduce the imaging quality.Based on this situation,it is especially important to model and calculate the degree of impact caused by flywheel micro-vibration during the pre-research phase.In the previous flywheel micro-vibration modeling and analysis process,the measured data of disturbance is usually directly loaded into the calculation model to obtain the degree of influence of disturbance on imaging quality,but this process will introduce a series of modeling errors,such as due to the theory modeling of flywheel disturbance source,the simplification of the finite element model,and the errors caused by the equivalence of boundary conditions,etc.,cause a large deviation between the analysis results and the measured results.The analysis shows that the theoretical modeling error of the flywheel disturbance source,especially the unmeasurable disturbance source swing mode error caused by the coupling characteristics of the flywheel and the whole satellite,is the main factor affecting the accuracy of the analysis.In order to improve the analysis accuracy,this paper conducts an in-depth study on the coupling characteristics of flywheel micro-vibration and the whole satellite,and proposes a numerical compensation method based on numerical analysis method for the compensation parameters of the coupling characteristics of flywheel disturbance and the whole satellite.It can compensate the equivalent stiffness and damping parameters of the flywheel mounting structure on the satellite.Firstly,the theoretical model of the flywheel disturbance source is studied,and the coupling mechanism between the flywheel disturbance and the whole satellite structure is analyzed.Based on the flywheel harmonic characteristics characterized by the flywheel rotor and bearing installation errors and the dynamic characteristics excited by the flexible installation of the flywheel,the Lagrangian method was used to model the disturbance characteristics and coupling mechanism of the flywheel.Theoretical analysis shows that the equivalent stiffness and damping of the flywheel installation determine the coupling characteristics.The characteristic frequency and disturbance amplitude values of the radial modal characteristic data will change with the change of the installation stiffness and damping.Therefore,when the equivalent stiffness and damping of the installation on the flywheel are different from the equivalent stiffness and damping of the special measuring platform,inputting the disturbance data obtained by the special measuring platform as the finite element model will cause some error in the analysis results.Then,a numerical algorithm is proposed to compensate the coupling characteristics of flywheel micro-vibration and the entire satellite.Based on the theoretical model of the flywheel source and the theoretical model of the whole star transfer function,the coupling characteristic parameter compensation algorithm is constructed by using the nonlinear programming method with the equivalent stiffness and damping parameters of the flywheel installation as the design variables and the minimum root mean square error of the estimated and measured image motion data as the optimization objective.The algorithm can compensate the equivalent stiffness and damping of the flywheel installation on the satellite.Then,the effectiveness of the algorithm was experimentally verified.In order to obtain high-precision flywheel vibration data,a Kistler micro-vibration measurement platform and a signal processing system are used to collect the vibration data generated by the flywheel in a certain type of optical remote sensing satellite.In order to obtain high-precision imaging image motion data caused by a single flywheel,a highsimulation satellite imaging platform was designed and constructed to conduct a singleflywheel slit imaging test,so as to obtain image motion data caused by a flywheel.After that,the experimental data and coupling characteristic parameter compensation algorithm are used to compensate the equivalent stiffness and damping of the satellite flywheel installation,and the estimated image motion data before and after parameter compensation are compared.The comparison results show that the prediction accuracy of the image motion data points after parameter compensation is significantly improved compared to the prediction accuracy before parameter compensation,which proves that this parameter compensation algorithm is feasible.Finally,the influence of test data background noise on the test results during the numerical modeling and estimation of flywheel micro-vibration was analyzed.Aiming at the problem of quantitative analysis of the influence of background noise on the estimated image motion in the numerical modeling and estimation process of flywheel micro-vibration after the compensation of coupling characteristic parameters,a background noise analysis method based on Monte Carlo simulation was proposed.Using this analysis method,the normal distribution parameters of the image motion error caused by background noise and the fitting curve of the distribution probability density curve are given.The sensitivity of the error caused by the background noise of the flywheel disturbance data and image motion data is analyzed.This analysis method can provide a possibility for evaluating the degree of influence of background noise on image motion in the numerical modeling and analysis method of flywheel microvibration,and perfect the numerical modeling process of flywheel disturbance.It can also provide a reference for the background noise analysis of flywheel micro-vibration related research.