Direct gravity estimation and compensation in strapdown INS applications

This paper proposes a novel algorithm for estimating the changes of gravity and compensating its effects on acceleration measurements in inertial navigation system (INS) based applications. Gravity is a critical factor and its effects are usually included in the measurements obtained from accelerometers. This results in a need to eliminate gravity effects from the measurements in order to accurately determine the true acceleration of a moving object. In the present study, a new method has been proposed to estimate the gravity using the measurements from the existing INS sensors without employing any additional sensors. This significantly reduces the complexity of INS based system design. Two different types of models have been developed based on the proposed gravity compensation method to be used in Gyro-Based and Gyro-Free INS applications. The performance of both these models is illustrated by simulations and experiments. Results of simulations demonstrate that by including the proposed gravity compensation model, the errors in the acceleration measurements reduces significantly.