Inertial Navigation and Geophysical Invariants

The paper is devoted to the problem of improving the accuracy of strapdown inertial navigation systems (SINS) both during the initial alignment and in the autonomous reckoning of coordinates. The proposed solution to the problem is based on the use of geophysical invariants and their combinations for observing SINS errors. At the initial alignment, in addition to the typical invariants associated with the immobility of the SINS base, the projections of the vectors of the angular velocity of the Earth's rotation and the acceleration of gravity on the axes of various coordinate systems are considered. In the SINS autonomous navigation mode, it is proposed to use the projections of the angular velocity vector of the Earth's rotation on the axis of the inertial coordinate system as invariants. Such projections are compared with their values calculated in the SINS. The observations formed on this basis are used to estimate SINS errors using the extended Kalman filter. The results of full-scale experiments with the integrated inertial-satellite navigation system SINS-500NS are presented and analyzed.