Abstract
In the work reported in this paper, a lost-in-space star pattern identification algorithm for agile spacecraft was studied. Generally, the operation of a star tracker is known to exhibit serious degradation or even failure during fast attitude maneuvers. While tracking methods are widely used solutions to handle the dynamic conditions, they require prior information about the initial orientation. Therefore, the tracking methods may not be adequate for autonomy of attitude and control systems. In this paper a novel autonomous identification method for dynamic conditions is proposed. Additional constraints are taken into account that can significantly decrease the number of stars imaged and the centroid accuracy. A strategy combining two existing classes for star pattern identification is proposed. The new approach is intended to provide a unique way to determine the identity of stars that promises robustness against noise and rapid identification. Moreover, representative algorithms implemented in actual space applications were utilized as counterparts to analyze the performance of the proposed method in various scenarios. Numerical simulations show that the proposed method is not only highly robust against positional noise and false stars, but also guarantees fast run-time, which is appropriate for high-speed applications.
Highlights
IntroductionThere has been an increasing demand for spacecraft with fast attitude maneuverability
There has been an increasing demand for spacecraft with fast attitude maneuverability. Such high maneuverability is called agility, and agile spacecraft have the advantage of being able to image more ground targets than a non-agile satellite could in the same time
Sr = e or σ2r,1 = σ2b,1, σ2r,2 = σ2b,2, σ2r,3 = σ2b,3. This implies that R and B apparently possess the same singular values with the change of direction cosine matrix caused by coordinate transformation
Summary
There has been an increasing demand for spacecraft with fast attitude maneuverability. Some recent literature has focused on fast identification of stars for agile spacecraft or for fast recovery after an abrupt power outage [17,18] They did not focus on the dynamic conditions that change with rapid attitude maneuvers. As explained in [19], agile satellites with high angular maneuverability could significantly decrease the number of stars to be imaged, compared to a static condition. This additional constraint makes it very difficult to provide an algorithm able to promise robustness under this condition.
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