Research On Image Stabilization Control For The Space Telescope Based On The Arm Mechanism

During the staring and imaging process of Space Telescope, relative motionbetween imaging system’s optical axis and the objective target, caused by orbit’smotions and attitude’s change of the platform or carrier, external disturbance, anddeviation of control system, namely optical axis declination and jitter, caused theimage of the target blurred, leads to imaging quality declination. The role of imagingstabilization control is controlling the pointing of the telescope’s optical axis,depressing various disturbances to optical axis, realizing precise pointing andtracking to the expected target.Refer to the new idea which is using a similar mechanism like the robotic armas the image stabilization control of the telescope in the project of the internationalspace telescope at present, this dissertation using the arm mechanism which is driveddirectly by the permanent magnet synchronous motor (PMSM), focuses on the highaccuracy of the control technology, the main factors which imply control accuracy ofstabilizing system are analysed, the motive characteristic and the stable characteristicof the imaging stabilization system, the dynamic of the single-axis system and thecontrol algorithm and strategy which have the strong ability of anti disturbance areanalyzed and discussed.The factors impacting the control of image stabilization control system is analyzed, the motor characteristics (inverse model) of arm agency compensating forthe disturbance which is bring in by spacecraft attitude stabilization system isanalyzed, the mathematical model is established, and the mathematical simulationanalysis is implied. Meanwhile, for the image stabilization control system inertia andstability characteristics, stable mechanism of image analysis system is carried out,the image stabilization system mathematical model base on gyro-stabilized isdeduced, and the gyro installation under this condition is given.The kinetics model of single-axis image stabilization control system isestablished, and the kinetics equation is deduced, then the impact of the disturbancesof spacecraft on optic axis of telescope is obtained. Mathematical model of thewhole single-axis stable image control system is investigated, and its angular speedtracking model is attained. The model for speed tracking of stable image controlsystem with PI control is studied in MATLAB/SIMULINK, and the impact ofdisturbances on the performance of control system is analysed.On the reference model of the disturbance compensation control method and thecontrol method based on extended state observer, better to overcome the systeminternal friction and disturbing moment, improve the control precision of the system.In view of the drive motor internal parameter perturbation problem in actualoperation, put forward the step of adaptive steppingback control speed trackingstrategy, can realize completely decoupled internal system parameters, andeffectively restrain the influence of parameter change on the system dynamic andstatic, has realized the fast response, no overshoot high steady precision, speedsteady and smooth, make the system have strong robustness.Based on the principle prototype to tracking system of space optical imagingsystem, respectively, to the traditional frequency analysis method in lead correctionwith integral, lag correction, disturbance observer based on the reference model oflead correction with integral, and based on the extended state observation of linearcontrol methods, such as proportional control experimental verification, and theseveral control methods of the experimental results are analyzed, the control performance of each control method is evaluated.