SINS In-Motion Alignment for Initial Attitude Uncertainty

This paper presents a novel alignment method based on wander frame for SINS (strap down inertial navigation system) whose initial attitude information is completely unknown. During the coarse mode, the cosine and sine of the wander angle is defined as the filter states, and modeled as the velocity/position error in the geographic frame. Azimuth error state in the fine mode of the filter is defined as wander angle error to provide continuous estimation of navigation states. For the wander azimuth navigation frame, the initial wander azimuth error is satisfied all arbitrary value from 0 to 360 degree. The design can solve the SINS alignment problem while the initial attitude information cannot be obtained from outside source. Compared with conventional algorithm, this approach is more robust and versatility for the fast reaction application.