Parametric Processing for Two-Dimensional Digital Sun Sensors: Algorithms, Modelling, and Testing

Abstract

This paper presents the modeling, algorithm development, and laboratory testing of a two-axis digital sun sensor. The basis for our modeling is the Sinclair Interplanetary SS-330, a sensor that employs a single linear array to provide two-axis measurements of the sun vector. The detector illumination simulation includes consideration of Fresnel diffraction, finite pixel size, the extended nature of the sun, and a detector-noise model to synthesize artificial images. Simulated images agree with actual sensor images to within about 3.2% (root mean square). Algorithm studies contrast the performance of existing peak-detection routines (e.g., peak detections and centroiding) with more sophisticated parametric algorithms. Laboratory studies confirm that thesemodified algorithms can provide a threefold performance improvement over the baseline sensor processing. These results also evaluate the simulation’s ability to provide accurate estimates of sensor performance. Although the simulations qualitatively replicate many behaviors, they are not yet accurate enough to be used in place of hardware validation.