Initial rapid alignment/calibration of a marine inertial navigation system

Generally, the conventional strapdown marine inertial navigation system needs about 4 hours to settle the initial alignment/calibration under motion. The paper presents an effective approach of the initial rapid alignment/calibration on a strapdown marine inertial navigation system with three fiber optic gyros and three conventional accelerometers. In this approach, a modified least square filter, which implements a pre-filtering scheme of the measured signal disturbed by the ship's motion, is used to improve the accuracy and settling time of alignment/calibration. The accuracy and the settling time in this system are limited by the performance of a modified least square filter of the measured signal. The authors confirmed the validity of this approach to improve greatly the accuracy and the settling time from simulation results. >