Coarse alignment based on IMU rotational motion for Surface Ship

Advanced development of Strapdown Inertial Navigation System (SINS) using Inertial Measurement Unit (IMU) rotational motion technology is described. The purpose of this project is to determine the feasibility of averaging out the inertial component bias in order to improve the accuracy of alignment. The traditional method of ground coarse alignment, which based on the assumption that SINS is on a stationary carrier limited the IMU´s rotation, therefore cannot be used to perform the Surface Ship coarse alignment based on IMU rotational motion. The novel method using the gravity in the inertial frame as a reference for Surface Ship alignment with IMU rotary motion is detailed in this article. The proposed coarse alignment method was applied on simulation and turntable-test. The results showed that the attitude determined by this novel method can meet the accuracy requirement of coarse alignment and it can be used as the input of fine alignment.