A Fast Anti-Rocking Self-Alignment Method for Strapdown Inertial Navigation Systems under Latitude Uncertainty

In order to realize the initial alignment of Strapdown Inertial Navigation Systems (SINS) in finite time under the condition of unknown latitude, a fast anti - rocking self alignment method is proposed based on the inertial frame initial alignment principle. In the coarse alignment stage, latitude self-estimation and coarse alignment are carried out simultaneously. Aiming at the problem that the measured values of accelerometer with random noise affect the latitude estimation, Kalman filter is used to identify the parameters and apparent acceleration of gravity is reconstructed, and the apparent acceleration of gravity is integrated with the determined optimal integral interval to effectively suppress the random noise and improve the alignment accuracy. The data stored during the coarse alignment process is used for forward fine alignment, which can significantly shorten the alignment time. The semi-physical simulation shows that the proposed method can realize latitude estimation and accurate initial alignment under the condition of unknown latitude.