An Angle Alignment Method for Ultrashort Baseline Underwater Positioning Based on the Weighted Total Least Squares Method

Ultrashort baseline (USBL) underwater positioning is widely used to provide location-based services to underwater uncrewed vehicles, but its accuracy is often compromised by angle misalignment errors. In this contribution, a novel angle alignment method for precise USBL underwater positioning is proposed based on the weighted total least squares (TLSs) method. We propose a new TLS-based functional model (TLFM) that simultaneously accounts for errors in both the coefficient matrix and the observations. A corresponding stochastic model is then established according to the covariance propagation principle. Robust estimation is also introduced to further improve the accuracy of angle misalignment estimation. To validate the effectiveness of the proposed method, both simulation and field tests were carried out. The simulation results show that the proposed TLFM method improved the precision of angle misalignment estimation by up to 19.48% compared to the least squares (LS) method. Field tests conducted in Jiaozhou Bay show that the accuracy of the proposed TLFM method was improved by 8.75% compared to that of the LS method and by 66.08% relative to that of the uncalibrated USBL positioning system.