Improvement of the Position Estimation for Underwater Gliders With a Passive Acoustic Method

Underwater gliders are widely used in ocean observation with long operational endurance. Since gliders use buoyancy to generate gliding motion through water columns with a pair of wings, they are susceptible to ocean currents. With the limited navigation capability, the position deviation is usually quite large. To improve the localization accuracy of the glider, a passive acoustic method is proposed, in which a sound source periodically sends signals and two hydrophones mounted on the glider are employed to receive signals. The extended Kalman filter is developed to estimate the positions of gliders and the depth-dependent currents using the time difference of arrival between the signal receptions and the direction of signal arrival. Both the hydrophones and the source are assumed as nonsynchronous, and to obtain the direction of arrival, an algorithm using the self-noise to synchronize two hydrophones mounted on the glider is proposed. Simulations with different scenarios are carried out and data from a field experiment performed at the South China Sea are processed to demonstrate the method.