Isolation And Experiment Research Of Micro-vibration For Integrated High Resolution Remote Sensing Micro-satellites

With the continuous application of aerospace remote sensing information technology in the development of the national economy,environment and disaster monitoring,scientific research and military fields,the technology is undergoing unprecedented development.At the same time,to satisfy the requirements of spatial and temporal resolution,the development of satellite is gradually moving towards high resolution and miniaturization.High resolution micro-satellites have attracted more and more attention due to their high resolution,small size,low cost,short development cycle and easy networking.As the executive component of satellite attitude control system,the flywheel will inevitably produce a series of micro unexpected disturbances under working condition due to the errors in its manufacturing and assembly process(such as rotor imbalance,bearing defects,etc.).Micro-vibration will not cause damage to the structure of optical load or electronics equipment,but it will affect the imaging quality of the optical load resulting in degraded imaging performance.As the increasing resolution of optical satellite,optical loads become more sensitive to micro vibrations.Due to the constraints of size,weight and development cycle of micro-satellites,greater difficulties are faced for the isolation design and on-ground test of micro-vibration.Isolation and experiment technology for micro-vibration has also become a key technology that needs to be broken through in the development of high resolution remote sensing micro-satellites.The research of this paper is based on a certain type of high resolution optical remote sensing micro-satellite in the "Jilin-1" satellite constellation.The mechanism of flywheel disturbances and the influence of micro-vibration on optical loads are systematically and deeply studied based on theoretical analysis,simulation analysis and test.New methods for flywheel disturbances suppression and micro-vibration onground test of whole satellite are proposed.The main work in this paper can be summarized briefly as follows:The causes of flywheel disturbances are analyzed in detail from two aspects of structural disturbance and harmonic disturbance,the mechanical model for each disturbance is established corresponding to its characteristics.A flywheel disturbance test platform is established based on the Kistler Table test system.Two different types of flywheels are tested and the dynamic characteristics of the flywheel disturbances are analyzed.The integrated design concept is used with the requirements of the launch and onorbit section taken into comprehensive consideration.The optical load and flywheels are rationally arranged in the satellite.The multi-objective optimization technology based on genetic algorithm is used to optimize the main structure of the satellite,the optimal size of carbon fiber cylinder which satisfies the fundamental frequency requirements of lift-off and isolation is obtained.The finite element method is used to analyze the dynamic and thermodynamic response of the satellite,and the results meet the design requirements.The optical system and attitude control system of the satellite are analyzed,then the optical amplification coefficient and high-pass filtering approximation scheme are derived.The integrated analysis model of satellite is established based on mechanical model and the influence of flywheel disturbance on the imaging quality of optical load is calculated.A dual-layer isolation theory is established based on the single-layer isolation theory.The function of the force conductivity is derived and the sensitivity analysis of the key parameters is performed.The damping mechanism and mechanical characteristics of the viscoelastic damping material are analyzed.The silicone rubber is tested and the relationship between the stiffness and damping with the temperature is obtained.The influence of basic flexibility on the precession decay time of the flywheel is analyzed,a dual isolation scheme for the flywheel and a dual isolation scheme for the satellite are designed respectively.The micro-vibration integrated analysis method is used to predict the suppression effect of the two isolation systems.The imaging principles of optical load is analyzed and the optical imaging microvibration test scheme is designed.A test platform is built for testing the high resolution optical satellite.The influence of flywheel disturbance on the imaging quality of optical load is tested in the conditions of satellite without isolation,under dual isolation for flywheel and under dual isolation for satellite.The pixel offset results of the focal plane center point and the vibration attenuation efficiency of the two isolation systems are obtained.The effectiveness of the micro-vibration integrated analysis method is verified by comparing the results of imaging test with the results of simulation analysis.A non-optical imaging micro-vibration test scheme based on high-accuracy acceleration sensor is established.The non-optical imaging micro-vibration test is performed on the satellites with two different optical system imaging modes.The test results are very consistent with the results of imaging test,verifying the correctness of the non-optical imaging micro-vibration test scheme.Moreover,the correctness of the on-ground test method and the feasibility of dual isolation for satellite are verified through the on-orbit micro-vibration test.