Method for determining azimuthal direction relative to true north
AssigneeRaytheon Company
InventorGeorge P. Maselli
Life of this patent
Estimating the term…
Abstract
Disclosed herein is a method for determining azimuthal direction relative to true north using gyroscopic apparatus. The input axis of a gyroscope is rotated at a substantially constant rate about the local vertical axis. A series of precessional rates at the gyroscope's output axis is measured as the input axis rotates through a predetermined portion of each half revolution. The predetermined portion of each half revolution of the input axis is in known relationship to the heading or reference being determined. Each difference in successively measured ones of the series of precessional rates is filtered to reduce the effect of drift within the gyroscope and thereby accurately determine the azimuthal direction of such heading relative to true north.
Claims10
A method for determining the difference in direction between a reference direction and a direction related to the earth's rotational axis using gyroscopic apparatus, such apparatus having an input axis, a spin axis and an output axis, each one of such axes being orthogonal to the other two of such axes, comprising the steps of:
- a. continuously rotating, at a substantially constant rate, the input axis about the earth's vertical axis;
- b. measuring, as the input axis is rotated, the precessional rates and accompanying restraint torques at the output axis during successive periods of time in which the input axis is rotated through a predetermined angle after having been aligned with the reference direction;
- and
- c. determining the difference between the measured precessional rates and accompanying restraint torques at the output axis in successive ones of such periods of time, each such difference being indicative of the then existing difference in direction between the reference direction and the direction relative to the earth's rotational axis.
Dependencies are inferred from the claim text.