Hull Deformation Measurement With Large Angles Based on Inertial Sensors

The partial reference is used in large ships to measure the hull deformation, which is normally realized through the transfer alignment between the master inertial navigation system and the slave inertial navigation system. In recent years, the matching methods based on several inertial measurement units has become the development trend to avoid the initial alignment of the slave system. However, these methods always require that the deformation angle is small and the system model can be regarded as a linear model. The purpose of this article is to solve the large deformation problem through coarse estimation based on the optimized attitude determination and propose an improved transfer alignment method based on the attitude matching in the inertial frame. The coarse estimation does not rely on the deformation model and can decrease the deformation error to a small angle in a short time. Then the system model and the measurement model are built to carry out the attitude matching in the inertial frame, which is stable and can avoid initial alignment. The swing table test show that the proposed method can estimate the large deformation between the two IMUs rapidly and precisely.