Analysis And Design On Space Stabilized Inertial Navigation System

So far, electrically suspended gyroscope (ESG) is the highest precise gyroscope forhigh-precision and long-time continuous underwater navigation system. In the past it is in theform of the electrically suspended gyroscope monitor (ESGM) combining with inertialnavigation system based on liquid floated gyroscope. But this group system has shortcomingsof large-volume and high-cost. Current foreign countries have begun to constitute inertialnavigation system based on ESG directly. ESG can not force moment, so it can only usemechanical configuration of space stabilized inertial navigation system (SSINS). The paperanalyzes and designs SSINS. The major tasks include:Firstly, the global gravitational field model, normal gravitational field model anddisturbance gravitational field model are derived. Then we give the reference earth model ofCGCS2000as the navigation basis for SSINS. Finally, we define the coordinate frame usedin the paper and derive the transformation relationship between them.The scheme of SSINS whose inertial frame is used for navigation frame is proposed, andthe system error equation is derived. We point out that the system error grows exponentiallyover time which is caused by the system itself in order to calculate the position vector modulein the gravitational model, and then put forward gravity correction method for introducingexternal height to calculate the position vector module. This method inhibits the systemerror divergence aroused by gravity. This paper analyzes and emulates the influence ofvarious error sources for SSINS on the stationary state related to inertial frame (navigationframe).The scheme of marine SSINS is designed. The scheme bases on ship moving along thesurface of the Earth. Firstly, this scheme calculates navigation information related to inertialspace, and then through coordinate transformation gained navigation information related tothe ground. And the average earth radius replaces the position vector module in thegravitational model. Conversion relationship between the navigation error related to inertialspace and the navigation error related to earth is derived. We analyze and emulate theinfluence of various error sources for marine SSINS on the stationary state related to earth.The comparative analysis of the error characteristics between the stationary state related toinertial space and the stationary state related to earth is studied.The scheme of marine SSINS whose geographic coordinate frame is used for navigationframe is proposed. The scheme can calculate navigation information related to earth directlyand does not require gravity compensation. The scheme’s error equation is derived. Analysis and simulation to verify the influence of various error sources in the static base is done. Forcomparative study with this new scheme, the error equation of the original scheme of SSINSwhose variables is navigation error related to earth is derived. The results show that the errormagnitude of the two schemes is same, but the law of error propagation is different.The scheme of strapdown marine SSINS is proposed. We analyze and emulate theinfluence of inertial instruments errors for strapdown system in the state of stationary base.And comparative study with platform SSINS is done. Because the direction of inertialinstruments is different, making platform and strapdown SSINS is no longer thesame. Finally, a strapdown SSINS bases on fiber optic gyroscopes is built, laboratory statictest verify the correctness of theoretical analysis.