Inertial navigator error models for large heading uncertainty

This paper is concerned with the development of a modified ψ-angle error model for a strapdown inertial navigator whose platform azimuth is completely unknown, as would be the case during initial coarse heading alignment. The paper is a review of the author´s (1994) previous paper, and provides a framework for developing large azimuth uncertainty error models. It then presents the development of a ψ-angle error model as a generalization of the ψ-angle small error model described by Benson (1975), and a modified ψ-angle error model as a generalization of the modified ψ-angle small error model presented by Wauer (1976) and Scherzinger-Reid (1994)