The Influence of Atmospheric Density Error on SINS/RCNS Integrated Navigation

The atmospheric density error affects the accuracy of the strap-down inertial navigation system (SINS)/refraction celestial navigation system (RCNS) integrated navigation seriously by degrading the accuracy of the atmospheric refraction model. At present, the mechanism and extent of the impacts of atmospheric density error on measurement models of SINS/RCNS integrated navigation are unclear. To solve this problem, this study first derives the relationship among atmospheric density error, measurements and measurement models (including refraction apparent height, refraction angle, and star pixel coordinates) of SINS/RCNS integrated navigation. Then, the quantitative relationship is provided based on it. The results show that 3.0% atmospheric density error can cause average errors of 190.22 m in refraction apparent height measurement, $9.43~"$ in refraction angle measurement model, and 0.27 px in star pixel coordinates measurement model. And these errors increase approximately linearly with the increase of atmospheric density error. Furthermore, simulations are carried out to verified the theoretical derivation and the linear relationship between the impacts of the atmospheric density error, which has a significant impact on position error and a relatively small impact on velocity error and posture error. When the atmospheric density error are 3.0%, 6.0%, and 9.0%, the position errors of the SINS/RCNS integrated navigation are about 1.4 times, 2.1 times, and 2.9 times of those without atmospheric density error. The research provides a theoretical basis for the elimination of the atmospheric density error.