A New Integrated Orientation Method for UUV Fused with Polarization Pattern and Light Intensity

The underwater polarization orientation is a hotpot and challenge issue in autonomous navigation field. With the increasement of the water depth, the underwater polarized light intensity and the polarization orientation accuracy decreased either. In this paper, to enhance the depth adaptability of underwater polarization navigation system, a new integrated orientation method fused with polarization pattern and light intensity is proposed. To be more specific, the information quality of underwater polarization pattern and light intensity related to the water depth are quantified, and the fusion factors associate with the polarization pattern and light intensity are established. In addition, to enhance the sun vector fusion accuracy in underwater uncertainty conditions, the weights of fusion factors are adjusted by water depths. Then the sun vector fusion is combined with the miniature inertial measurement unit (MIMU) to determine heading. Finally, in order to verify this method, underwater experiments in actual ocean scene were carried out. The results exhibited that the proposed method show sound performance with different depths, and accuracy is 0.30° (RMSE) at the depth of 7 m, 1.98° (RMSE) at the depth of 15 m, and 2.05° (RMSE) at the depth of 20 m.