Читать книгу Global Navigation Satellite Systems, Inertial Navigation, and Integration - Mohinder S. Grewal - Страница 45

The initial solution to the inertial navigation problem is the starting position and orientation of the ISA. The starting position must usually be entered from other sources (including GNSS). If the ISA is sufficiently stationary with respect to the Earth, its starting orientation with respect to local vertical can be determined from the accelerometer outputs. If it is not at the poles and its rotation sensors are sufficiently accurate, its orientation with respect to North, East, South, and West can be determined by sensing the direction of Earth rotation. Otherwise, if the local Earth magnetic field is not too close to being vertical, it can be oriented using magnetometers. Other alternatives are mentioned in Chapter 3.