Initial Alignment, Rotation Fiber-optic Gyro Strapdown Inertial Navigation System

FOG (Fiber Optic Gyro) is a kind of optic gyro that developed in 1970s. Strapdown inertial navigation system (SINS) based on FOG will be one of the main commercial or military INS market members in 21st centuries. The initial alignment is the key technique that influences the system performance. The accuracy and speed of alignment relate to the accuracy and the start characteristics of the inertial system directly.Based on one medium/low accuracy FOG SINS, initial alignment methods are experimentally studied. Through analysis, the FOG SINS errors mainly come from bias of IMU. According to this characteristic, it is necessary to modulate and restrain the bias of IMU in the initial alignment. To this, the thesis has done these work on the following studies:1.Adopting classical gyrocompass methods, it carries out an initial alignment research on static base;2.Using SVD method, it analyses the observability and degree of observability during the initial alignment of SINS on two-position .And it studies Two-position Kalman filter initial alignment method through experiment.3.Given the situation of SINS continuous rotation, it analyses the change of system error and experimentally studies the initial alignment using Kalman filter method.The result shows that the alignment accuracy of classical gyrocompass method is low due to the non-compensated bias of IMU. Two-position Kalman filter can estimate and compensate the biases of gyros and accelerators, and thus the accuracy is improved. Continuous rotation Kalman filter can modulate and restrain the bias, which greatly improves the alignment accuracy compared with above two methods.