Inertial Navigation System Standardized Software Development. Volume II. INS Survey and Analytical Development

Abstract

Abstract : Section 1 of this volume provides a summary of the navigation computations for seven aircraft inertial navigation systems (INS): four of the INS are local ve tical systems (north slaved, wander azimuth and free azimuth); one INS is space stable; and the remaining two are strapdown. Section 2 presents the detailed navigation and attitude equations, applicable to any of the aforementioned INS, using both local vertical wander azimuth (LVWA) and space stable computational frames. The LVWA frame is selected for the development of standard navigation algorithms using a standardized notation and symbology. The algorithm is similar to that used in several existing moderate accuracy, local vertical, aircraft INS. The upgraded algorithm contains several minor modifications to the baseline algorithm which improve the computational accuracy of the latter. The modifications are derived in the appendices. Transformations required to use the standard algorithms with space stable or strapdown systems are also presentec in this section. Section 3 summarizes the INS computations presented in the previous section. Section 4 provides a survey of the use of INS computations by other avionics subsystems, with particular reference to the parameters, formats, data rates, and accuracy requirements. Section 5 presents the tradeoffs leading to the selection of the LVWA computational frame for the standard algorithm. Section 6 (and Appendix A) present the standardized symbology and frame definition employed in the standard algorithms and simulator development.