High accuracy star image locating and imaging calibration for star sensor technology

Today aircraft attitude measurement technology plays an important role in an aircraft system because it can provide orientation for aircraft in action. Lately star sensor technology used in aircraft attitude measurement has become more and more popular because of its high accuracy, light weight, without attitude accumulation errors and other advantages. There are three main steps for star sensor to measure aircraft attitude, star image locating, star identification and attitude tracking. The latter two steps are based on the accuracy of star image locating. So it's critical to make efforts to advance the accuracy of star image locating. Some imaging errors, such as spherical aberration or coma aberration, also have negative effect on the accuracy of star image locating, of which the effect is necessarily reduced as well. At the beginning of this article, the structure of star sensor hardware is introduced. Secondly three methods for star image locating are described specifically, which are traditional centroid method, Gauss quadric fitting method and improved Gauss quadric fitting method. Subsequently an imaging calibration method is described for the purpose of reducing the effect of imaging errors. Finally the experiment shows that the accuracy of the star sensor is 2-arc-second.