Fog Strapdown Vertical Datum Technology Research

The ship's vertical reference system is the measure instrument determining the level angles of a shipborne system,which is used abroad in the stabilization of the ship's antenna,the dynamic stabilization of the collimation ,the initial alignment of the helicopter's heading and attitude reference system,and the rapid transfer alignment of the long-distance fish torpedo and the missile on moving base.Fiber optic gyro is a new type of inertial measure unit,and the SINS with FOG is also a hotspot in the navigation research field ,the research and application of which is just at the beginning in our country.Under the precondition ,the target of this thesis is to research the technical route of the realization of the ship's FOG strapdown vertical reference system with medium precision.The thesis is composed of two parts.The first part is the research of the model of FOG's bias drift at high temperature ,the intention of which is to improve the accuracy of FOG through the algorithmic compensation .The experiment shows that the performance of the tested FOG is better in the condition of high temperature.The bias drift at invariable temperature is minished througn Kalman filter which is based upon ARMA model.And the filter result is analyzed by frequency spectrum and Allan variance analyzing method,the results show that this method can effectively improve the accuracy of FOG.The second part mainly dwells on the realizable principle of the vertical reference system and different methods.The most popularerror model of SINS on moving base and three themes (namely Kalman filter , H∞ filter andvelocity error linear feedback )based on velocity matching are systematically discussed . Two kinds of research methods are adopted: one is simulating research based on MATLAB/Simulink, the other is the hardware-in-the-loop real-time simulation using strapdown inertial measurement unit (SIMU) which is composed of three FOGs and three accelerometers and three-axis rate table.The experiment demonstrates that three methods all can achive the goal.The velocity error linear feedback can obtain high precision ,but the speediness is lower than Kalman filter andH∞ filter.For the medium precision system with nondeterministic noise ,H∞ filter has higheraccuracy and better robust characteristic than Kalman filter. Based on the existing equipments ,the roll and pitch errors of the velocity error linear feedback during the hardware-in-the-loop real-time simulation can be confined to 2 (within 250 seconds),the rollerror is confined to 2.8 ,the pitch error is confined to l'(within 20 seconds)using the H∞ filter.In contrast to Kalman filter,the level angles' errors are confined to 2.8 and 8.6 (within 40 seconds).