The coarse alignment of strap-down inertial navigation system for ship

A coarse alignment of strap-down inertial navigation system (SINS) for ship was researched. Three coarse alignment methods of the traditionally analytical, the second order leveling, azimuth estimation and the novel freezing analytical were deduced, of which the last method is that the calculation of attitude matrix is based on the gravity acceleration information in the inertial coordinate. The stationary and swing bases were simulated and analyzed. The last two methods were used for a real SINS based on the fiber gyroscopes and accelerators for a real ship testing at mooring. The test results show that the coarse alignment can be done effectively using the freezing analytical method, and the fine alignment can be allowed based on it.