Research On Initial Alignment For Ring Laser Gyroscope Platform Inertial Navigation System On Quasi-static Base

Ring Laser Gyroscope (RLG) is a core measurement sensor in Platform Inertial Navigation System based on Ring Laser Gyroscope (RLG PINS). The initial alignment must be done before navigation in which the platform coordinate is adjusted to concide with the navigation coordinate. The accuracy of initial alignment has a great influence on navigation accuracy. Based on the fundamental of initial alignment, the method using Kalman filter to fulfill the alignment on stationary base and on swing base is studied. The main contents are as follows.Firstly, based on the analyses of the error equation of RLG PINS, a kind of method of initial alignment using Kalman filter is designed to fulfill PINS-alignment on quasi-static base, in which the errors of acceleration is used as exterior value of observation. The Kalman filter is applied to make the optimization estimation of attitude errors between platform coordinate and geography coordinate.Secondly, the alignment approach of PINS on stationary base is designed. The factors, which have an impact on the precision and speed of alignment, are analyzed with simulation.Thirdly, the special machineary of PINS can segregate the swing of marine, so the lever arm effect will be the main influence to the measurement of accelerator. Based on the analysis of lever arm effect, two approaches of solving lever arm effect are proposed. One is to correct lever arm error by calculating the length of level arm, and the other is to minish the error using Butterworth Lowpass Filter. The factors, which have an impact on the precision and speed of alignment, are also analyzed with simulation.Finally, after analyzing the influence of the accurary of initial alignment, the approaches, to improve the precison of inertial alignment through tesing sensors error in three angular positions, is studied.