Fine Alignment Algorithm for UUVs With a Large Misalignment Angle

In order to overcome the problem that the conventional algorithms cannot be applied in the polar region, a polar initial alignment algorithm for Unmanned Underwater Vehicles (UUVs) with a large misalignment angle is proposed in this paper. The error model, the dynamics model and the observation model of the polar UUV initial alignment algorithm is established under the grid frame. This initial alignment algorithm is designed for the temporary anchoring UUV. According to the complex environment in the polar region, the large misalignment angle is considered instead of the small misalignment angle in other algorithms. An unscented Kalman filter is used to realize the data fusion. Based on the characteristics of the dynamics and the observation model, the unscented Kalman filter is simplified. The errors of the velocity are chosen as the observations. The misalignment angle of UUVs is estimated by the simplified unscented Kalman filter. The results demonstrate that the polar UUV initial alignment algorithm can be effective in improving the initial alignment accuracy, especially when large misalignment angles occur.