Research On Hyper Accuracy Subdivision Position Technology Of Fine Guidance Sensor

Fine guidance sensor is a high-precision measurement of large-aperture spacetelescope image stabilization important part of the control system, is the mostprecise angular position of the measuring element. It uses the main optical system isextremely long focal length correlation algorithm to obtain highly accurate inertialangular position offset information in a way to fine-level image stabilization controlsystem provides feedback information to achieve fine control level stabilization loopcontrol system. In the case of the primary optical system, the focal length of thetelescope determined, star point positioning accuracy subdivision directly determinethe angular position measurement accuracy inertial measurement guide star system.In this paper as a background, the main research guide star measurement systemsuitable for subdivision positioning technology.CMOS detectors for low fill factor, affecting the shape of the photosensitivearea subdivision positioning accuracy is proposed based on least squares supportvector machine algorithm for error correction system. First analysis of statisticallearning theory, detailing least squares support vector machine regressionmathematical model, then as a theoretical basis for the establishment of the starpoint positioning system error correction model, and finally, the numerical simulation using Monte Carlo method, with Gaussian radial basis function kernelleast squares support vector machine regression analysis, the non-linear function ofsystem errors and centroid location and the ideal size and shape of the light-sensitivearea, and use this as a function of the heart after a confrontation estimates corrected.Tracking for high dynamic conditions and guide star problems CMOS detectorcan play any windows features, is proposed based on adaptive Kalman filteringsub-pixel subdivision algorithm. First study the Kalman filter theory, the star pointpositioning method is proposed to predict window and using a combination ofKalman filtering. Coarse location prediction method uses the gyro output windowINS information is star point star point in the measurement position predicted by thesmaller star point range to determine the position of the window, and then, usingthe Kalman filter for filtering coarse location, high output Star point accuracy. Asthe star point measurement position calculation in a small window, the proposedfast algorithm, while the Kalman filter can effectively suppress random noise, isparticularly suitable for measuring guide star system of such high magnitude starpoint low SNR image, can provide highly accurate satellite position information.Low-noise ratio for high-magnitude image and the image shift and errands likeoval spot problems, the use of statistical signal processing theory first spot signalmodeling to derive maximum likelihood estimation formula spot center, because themaximum likelihood estimate is a good performance unbiased estimator, whichconstitutes the theoretical basis of the iterative centroid algorithm. Then proposed aniterative weighted centroid calculation processes, statistical signal processing theoryto derive the Cramer-Rao lower limit when the number of iterations to infinity, thestar point positioning accuracy limits. When iterative weighted centroid algorithmconverges, Essentially using a Gaussian weight function weighted light intensity,increasing the signal to noise ratio of the image, and can be used in two differentGaussian width direction for oval spot, and finally, through numerical simulationresults show that the proposed algorithm has good performance.Build a ground test measuring guide star system, the proposed algorithm for authentication. First introduced the composition and working principle experimentsystem; then experiment parameters related devices for analysis; finally werecompensated by the system error experiments, static and dynamic accuracy of themeasurement accuracy of the experimental measurement experiments conductedexperiments to verify the proposed algorithm achieved the expected experimentalresults.Experimental results show that, under operating conditions guide starmeasurement system, the measurement accuracy of the proposed method comparedto the conventional positioning subdivision algorithm greatly improved. Researchresults have certain significance for the development of China’s space telescopeguide star precision measurement system.