ERROR ANALYSIS OF STRAPDOWN AND LOCAL LEVEL INERTIAL SYSTEMS WHICH COMPUTE IN GEOGRAPHIC COORDINATES

摘要

This report is a tutorial exposition of two broad classes of strapdown and local level-inertial navigation-systems, which perform their navigational computations in the local geographic coordinate frame. The strapdown chapter includes discussions of the direction cosine update procedure, alignment techniques and instrument redundancy. An analysis of error sources peculiar to the strapdown mechanization is followed by a perturbation type error analysis which shows that the basic error equations are identical to those which describe the behavior of the local level platform system. The error analysis of the local level system is followed by a rather complete set of analytic and computer solutions for both the stationary and moving navigation cases. The effect of the Foucault mode on the validity of the analytic solutions is discussed. The results of the error analysis are applicable to both navigation system mechanizations.