Gravity Model Performance in Inertial Navigation

Abstract

NERTIAL navigation has evolved to the point that the traditional gravity model is a principle error source in advanced, precise systems. Future autonomous strategic systems, such as the cruise missile, will likely require a more accurate gravity model. Mission success depends on navigation system accuracy, not gravity model accuracy per se. So an improved gravity model should be judged by systemlevel performance expressed, for example, as circular-erro rprobable (CEP). Statistical analyses based on Monte Carlo and linear state-space techniques have been used to produce this gravity model performance index. A brief review of these methods will clarify the need for a new analysis approach. The gravity model in an inertial navigation system (INS) is a subsystem or component providing one part of the information required for constructing position, velocity and attitude estimates. The total acceleration is given by