Error correction of the underwater inertial navigation system using movable surface acoustic reference stations

This paper presents an integrated underwater navigational algorithm for autonomous underwater vehicles using two movable surface acoustic reference stations which can transmit data packet to the AUV via acoustic modem with synchronous timer. This paper proposes a measurement model with the two range measurements that can improve the performance of an IMU-DVL (inertial measurement unit - Doppler velocity log) navigation system for long-time operation of the AUVs. Extended Kalman filter was adopted to propagate the error covariance, to update the measurement errors and to correct the state equation when the external measurements are available. Simulation was conducted with the 6-d.o.f. nonlinear numerical model of an AUV in lawn-mowing survey mode at current flow, where the velocity information is unavailable. Simulations illustrate the effectiveness of the navigation system assisted by the range measurements from two movable surface acoustic references.