Patent ID: 8725415

Claim:
A method of long-term navigation by means of an inertial unit having at least three gyros and at least three accelerometers associated with a system of axes X, Y, Z and mounted on a vehicle traveling relative to the Earth in order to measure movements relative to an inertial frame of reference having axes Xi, Yi, Zi, the method comprising the steps of: using the gyros in permanent manner to measure an orientation of the system of axes X, Y, Z in the inertial frame of reference; and starting from an initial orientation of the inertial unit, applying a predetermined sequence of turnovers to the inertial unit in the inertial frame of reference about a first axis and about a second axis, which axes are substantially perpendicular to each other in such a manner that: at the end of the sequence, the inertial unit is in a final orientation identical to its initial orientation relative to the inertial frame of reference; the turnovers cancel mutually within the sequence; and a succession of two turnovers about the first axis is preceded and followed by a turnover about the second axis, and a succession of two turnovers about the second axis is preceded and followed by a turnover about the first axis.