Conceptual Design on the Field of View of Celestial Navigation Systems for Maritime Autonomous Surface Ships

TL;DR

This paper investigates the optimal field of view for celestial navigation systems on maritime autonomous ships, balancing measurement accuracy and star observability to enhance positioning reliability.

Contribution

It provides a detailed analysis of how FOV size affects star identification success and positioning accuracy, proposing that larger FOVs are beneficial if measurement precision is maintained.

Findings

Larger FOV increases star observability but reduces measurement accuracy.

At least four stars are needed for accurate identification, but more are required for wider FOVs.

Maximizing FOV is beneficial if positioning accuracy requirements are met.

Abstract

In order to understand the appropriate field of view (FOV) size of celestial automatic navigation systems for surface ships, we investigate the variations of measurement accuracy of star position and probability of successful star identification with respect to FOV, focusing on the decreasing number of observable star magnitudes and the presence of physically covered stars in marine environments. The results revealed that, although a larger FOV reduces the measurement accuracy of star positions, it increases the number of observable objects and thus improves the probability of star identification using subgraph isomorphism-based methods. It was also found that, although at least four objects need to be observed for accurate identification, four objects may not be sufficient for wider FOVs. On the other hand, from the point of view of celestial navigation systems, a decrease in the measurement accuracy leads to a decrease in positioning accuracy. Therefore, it was found that maximizing the FOV is required for celestial automatic navigation systems as long as the desired positioning accuracy can be ensured. Furthermore, it was found that algorithms incorporating more than four observed celestial objects are required to achieve highly accurate star identification over a wider FOV.