In view of the influence of underwater unknown constant currents in autonomous underwater vehicle(AUV)
cooperative localization, an AUV cooperative localization method based on motion radius vector in the presence of currents
is presented. The model of the system is established by using the AUV kinematic equation and the motion radius vector
measurement equation. A cooperative localization filtering algorithm is designed by using extended Kalman filtering(EKF),
which is used to estimate the currents speed and compensate the AUV position error. The simulation result shows that the
unknown currents speed can be estimated and the localization accuracy is improved effectively.