A new high-precision SINS/CNS deeply integrated navigation scheme

To address the problem of degraded long-endurance positioning performance caused by limited horizon accuracy in celestial navigation systems (CNS), a new high-precision strapdown inertial navigation system (SINS)/CNS deeply integrated navigation scheme is proposed. First, the concept of mathematical horizon reference (MHR) is introduced, and a relationship model between MHR errors and celestial positioning errors is derived. Second, the indirect-sensing horizon reference independent of inertial navigation is constructed through stellar refraction navigation. A misalignment matrix is constructed by fusing it with the MHR, from which platform misalignment angle and gyroscope drift information are extracted and compensated in real time, thereby improving MHR accuracy and suppressing its long-term divergence. Furthermore, celestial angle measurements are constructed using the high-precision horizon reference, overcoming the problem of traditional latitude-longitude measurement model failure when the number of observed stars is limited. Finally, a new SINS/CNS deeply integrated navigation scheme is designed to achieve accurate estimation and correction of position, velocity, and accelerometer errors. Experimental results demonstrate that the proposed scheme effectively suppresses the divergence of horizon reference errors, improving the accuracy and reliability of the integrated navigation system. This provides a feasible technical approach for autonomous navigation of high-altitude long-endurance aircraft.