Gravity Field Modelling for INS
In all inertial navigation computations approximative formulae for the normal gravity are used. The gravity-induced position errors for an unaided INS are suppressed conventionally by increasing the vehicle speed (shortening the ZUPT-interval) or by modelling the local gravity disturbance, which is frequently limited in practical applications.
In the paper the exact computational formulae for the normal gravity will be described by using spheroidal coordinates. The error process of strapdown-INS will be presented in the earth fixed Conventional Terrestrial Frame, that has considerable advantages. A convenient method to improve the precision of the positioning will be outlined by increasing the frequency of the gravity model and simulation results for a timespan of the Schuler period are demonstrated.
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