Method for determining gravity in an inertial navigation system

摘要

The invention is a method for determining gravity in an inertial navigation system which periodically produces and stores in memory position coordinates. The method comprises the steps of (a) retrieving the most recently determined position coordinates, (b) determining coordinates Lu, Ln, Hu, and Hn from the position coordinates, Lu and Ln being predetermined functions of geodetic latitude and Hu and Hn being predetermined functions of geodetic altitude, (c) determining the vertical component of gravity by substituting either or both Lu and Hu in a first polynomial expression, (d) determining the north-south component of gravity by substituting either or both Ln and Hn in a second polynomial expression, and (e) utilizing the components of gravity determined in steps (c) and (d) in the next determination of the position coordinates.