| Star Sensor is an attitude sensor referring to observing stars, it has been widely used in space field. The traditional star tracker generally has a large weight, large volume and high power consumption and other qualities which prevent it being used in more applications. The traditional star tracker can’t fulfill the requirements of micro-satellite which is developing rapidly.In this thesis, nano star tracker technique is studied to overcome the resource constraints of micro-satellite and a nano star tracker prototype was completed. The main work and innovative achievements include:(1) A high-precision navigation star catalog for star tracker was established. Proper motion correction, aberration correction, parallax correction, precession and nutation correction is made.(2) The physical design and optimization of nano star tracker including star extraction, centroiding, star matching and attitude determination were done. Software design and testing were completed.(3) A star tracker distortion calibration model is established. Distortions of the engineering prototype is calibrated using a 6-axis high-precision hexapod and a collimator. The calibration residual error is approximately 0.0016 degree(5.72 arc second).(4) The engineering prototype was tested using on-ground measurement. The cross-boresight and around boresight accuracy is 5.5 arcsec and 56 arcsec. The attitude update rate is 8Hz. This technical indexes have reached leading level among same type international micro star trackers(5) A new method to calibrate the imaging sensor pixel displacement is proposed. And the star position error due to pixel displacement is studied by simulation. This can be used as a new method to develop high precision star tracker(sub-arcsec). |
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