Base motion isolation algorithm for rate biased RLG north finder with disturbances

A base motion isolation algorithm is proposed for a rate biased RLG (Ring Laser Gyro) north finder subjected to vehicle disturbances. A single-axis rotation modulation scheme is used. Furthermore, the angular increment of the rotation of the turn table is utilized to compute the outputs of the third virtual gyroscope, by which the north finder consist of two gyroscopes and three accelerometers are translated into a Strapdown Inertial Navigation System (SINS) consist of three gyroscopes (two real and one virtual) and three accelerometers. Therefore, the north-finding problem is translated into an initial alignment problem based on a Kalman filter. The experiments results show that the new algorithm can effectively avoid the influences of vehicle disturbances. The 20min north finding accuracy of azimuth angle is better than 1´ when the weather is gusty, the vehicle is rocking and the motor is running on.