Research On Design,modeling And Control Of Six-axis Spacecraft Vibration Isolation System

With the development of space technology,the pointing accuracy,resolution and stability of the high precision instruments on board the spacecraft put forward higher requirements for the mechanical environment.The micro-vibration of spacecraft produced by control moment gyroscopes,reacting flywheel and other power equipment seriously affects the performance index of high precision instrument and reduces the image quality.Therefore,the research on spacecraft six-axis vibration isolation system is carried out in this thesis.1.Research on the spacecraft single-axis vibration isolation system.First,according to the different vibration isolation requirements,the open-loop transfer function of the disturbance displacement transfer and the disturbance force transfer of the uniaxial isolator is established respectively.Then,the active vibration isolation effect based on the force feedback PI and the LADRC are analyzed with the disturbance displacement suppression as an example.Finally,the correctness of the theoretical derivation is verified by the active vibration isolation experiment,and the LADRC has a good vibration isolation effect at the 20-500 Hz full frequency band,the low frequency band attenuation rate is up to 10 d B,and the corner frequency and high frequency are 20 d B.2.The optimal design of the six-axis vibration isolation platform is studied.First,the homogeneous Jacobian matrix of vibration isolation platform is derived for the problem of rotation dimension and motion inconsistency of parallel mechanism Jacobian matrix.Then,the kinematic isotropic configuration of the vibration isolation platform is obtained based on the kinematic isotropy optimization index of the homogeneous Jacobian matrix.Then,the analytical conditions of isotropy of vibration isolation platform in free floating state are deduced.Final,the dynamic isotropy is used as the index to optimize the design of the vibration isolation platform,and the final configuration of the vibration isolation platform is selected.3.The modeling and optimal design of flexible hinges are studied.First,the flexibility equation of the arc flexible hinge is established by the structural matrix method.The warping torsional stiffness of the rectangular section is derived,and the approximate equation of torsional flexibility under the constrained torsional state is obtained.Then,the flexibility equation based on the flexible hinge aims at the rotational flexibility and axial stiffness of the flexible hinge.The bending flexibility of the optimized flexible hinge was increased by 5.12%,while the axial stiffness of the hinge was increased by 4.72%.Final,based on the flexibility equation of the single-axis flexible hinge,the flexibility matrix of the flexible hook hinge and the flexural stiffness analytic formula of the direction of the spherical hinge are derived.4.Dynamic modeling research of flexible vibration isolation platform was carried out.First,based on the spherical hinge bending stiffness analytic formula and the virtual power principle,the display dynamics equation of the free floating state flexible vibration isolation platform is established.Then,the virtual prototype model of the flexible vibration isolation platform is established.Final,the theoretical model is verified by the comparison of the acceleration and driving force of the flexible vibration isolation platform and the virtual prototype model.5.The vibration isolation performance of the six-axis vibration isolation platform is studied.The the decentral force feedback control of the six-axis vibration isolation system is studied,and the correctness of the decentral force feedback is verified by the simulation analysis of the active control of the six-axis vibration isolation platform based on the dynamic model of the flexible vibration isolation platform.Final,the performance of the six-axis vibration isolation platform is verified by the experimental research of active control system.