A Current Estimation Method Based on SINS/DVL Tightly Coupled Navigation Scheme

In the strapdown inertial navigation system (SINS)/ Doppler velocity log (DVL) integrated navigation, the DVL measures the earth-relative velocity of the autonomous underwater vehicle (AUV) to suppress the error accumulation of SINS. Nevertheless, the DVL has range constraints. When the AUV sails over oceanic trenches or in the mid-water zone far away from the seabed, the DVL may lose bottom track. In these cases, it measures the water-relative velocity, which will be affected by the water currents and further introduce errors in the navigation results. In this paper, an improved least squares (LS) based current estimation method is proposed. Based on SINS/DVL tightly coupled scheme, the proposed method avoids the problems of the traditional method, including the convergence delay and singular values. In most cases, it can immediately output the accurate current velocity when the DVL loses bottom track, so as to eliminate the effects of water current on SINS/DVL integrated navigation. The effectiveness and superiority of the proposed method is validated by semi-physical experiments.