| Inertial navigation systems play important roles in both military and civilian fields as important equipment of ships, aircrafts, spacecrafts and other carriers. ESG-based space-stable inertial navigation system has great research value, because it is suitable for military equipments such as nuclear-powered submarines due to its high-precision. At present researches on space-stable inertial navigation systems is given in this thesis for its engineering applications.Basis equations and error equations of the system are derived based on considering gravity vector effects mainly, according to characteristics of space-stable inertial navigation systems. The conclusion that gravity errors make the system divergent is got after analyzing characteristic equation of the system. The system gets oscillation characteristics instead of divergence after height information measured outside are introduced. Error characteristics of the system are simulated and analyzed based on that the carrier is static relative to inertial system.Analytical solutions under inertia frame have to be transformed to the ones under geography frame, so that its speed relative to earth surface and position can be got. Transform relations among all kinds of errors on inertial system and geography system are derived respectively in order to convenient for navigation control to the carriers. Error equations while carriers are stable relative to the earth are derived. Analytical collusions of all kinds of errors under inertia frame are got and simulated. The ones being transformed to geography frame are simulated also.Conclusions are given after a series of simulations and analyses. Gyro drift makes great effect to space-stable inertial navigation systems, it makes the system divergent. Errors of space-stable inertial navigation systems oscillate periodically and it is Schuler cycle oscillation .While carriers are stable to the earth errors oscillate periodically concluding Schuler cycle oscillation and earth cycle oscillation.
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