Fundamental Principles of Inertial Heading

Abstract

This paper discusses the problem of very high accuracy determination of the direction of north by gyro-compass means. It indicates the quality of gyroscope performance and vertical determination required, and demonstrates the effect of small forcing oscillations in disturbing the north pointing accuracy. Simplifications of the over-all gyro-compass loop equations are indicated; from these can be quickly estimated the amount of filtering required to obtain a given degree of accuracy under a particular environment. The basic purpose of the discussion is not to make the reader an expert in gyro-compass dynamics but rather to clarify the problem to a sufficient degree to equip him to understand better what can be hoped for in the way of accuracy and settling time under particular conditions.