Observability Analysis of a Single-Beacon Underwater Navigation Method With Unknown Effective Sound Velocity

For single-beacon navigation systems, the precision of the predetermined effective sound velocity (ESV) significantly affects the localization performance. However, the ESV between the pinger and receiver is time-varying, location-dependent, and difficult to determine accurately. ESV-setting errors induce large positioning errors and affect the practical applications of single-beacon navigation systems. Recently, unknown-ESV-based single-beacon navigation methods have been proposed to address the aforementioned issue, and their performances have been significantly better than those of known-ESV-based methods. This study aimed to conduct a theoretical analysis of the unknown-ESV-based single-beacon navigation methods in terms of observability. The local weak and global observabilities of an unknown-ESV-based single-beacon navigation system were investigated, and systems with and without ground-velocity measurements were considered. The observability of several common trajectories in underwater vehicles was summarized. Finally, a series of numerical simulations was conducted to validate the derived observability.