Digital Filter Design And Realization On Star Extraction

Star Sensor, which is widely used in the spacecraft is a high-precision, high reliability components of the attitude measurement. Extraction of the star from star map is an important work in star sensor system. Location precision of the star not only has a relation to attitude precision, but also affects efficiency of the star pattern matching.Currently, the star sensor has four main ways in the search for and track work, as the venue of the satellite images, space debris and removed large, relatively bright star selected as navigation satellites determine the NAVSTAR window. At this time, not store image, the whole process is completed in time. To keep up with the satellite tracking and capture capabilities, as well as to reduce the amount of memory storage, signal processing demands of real-time processing and high precision processing. This paper is focusing on both real-time and high precision required to conduct the studies.The work has done in this paper as following:(1) On analyzing real star map base, adopting on-line digital filter design method, the background and signal digital filters is designed. In this way, we make the star data low down and accomplished the object extraction. Making the star map into two values, we adopt dynamic threshold. Stars are not lost and the noise is not extracted, accomplishing the request of high precision.(2) All the real star map are processed, and the result is ideal. After we get the difference equation of the digital filters, the realization of the hardware is studied.(3) The centroid extraction is also studied, simulating in few methods, variance is prompted to compare with their virtue and defect, we get the best method and accuracy of the centroid reaches to subpixel.The designed digital filters fulfil requirements of star extraction, it provides security for the star sensor. Study on the centroid has a draw significance.