In-Motion Alignment for a Velocity-Aided SINS With Latitude Uncertainty
Qiangwen Fu, Feng Wu, Sihai Li, Yang Liu
Abstract
For situations where accurate attitude information is needed while the position is not readily available or not necessarily required, such as the attitude heading reference system, this article proposes a velocity-aided in-motion alignment scheme for a strapdown inertial navigation system (SINS) during geographic latitude uncertainty. In the coarse alignment stage, a gravitational apparent motion rebuilding method based on the integral velocity smoothing is designed to roughly determine the attitude and latitude information. Then, the SINS/velocity-integrated navigation method uses the recorded data to complete the fine alignment. Due to the adoption of a well-designed backtracking navigation strategy, the storage space and computation load are reduced to the degree that an ordinary navigation computer can work with. Nine ship tests were carried out and the results show that the proposed method can align the azimuth with an accuracy of 0.04° in a moving environment, which is the same as that of normal in-motion alignment with a known position.