Pure-inertial AHRS with adaptive elimination of non-gravitational vehicle acceleration

Abstract

Among the critical features of the Attitude and Heading Reference System (AHRS) is its ability to deal with an external, non-gravitational vehicle acceleration. When present, vehicle's acceleration becomes an inherent part of the accelerometer measurements, hindering them from being used for the direct estimation of the attitude. Reliable mitigation of the non-gravitational acceleration is of high importance, especially in the class of pure inertial AHRS systems, where the attitude of the vehicle is determined solely by use of inertial and magnetic field measurements, without any global navigation satellite system (GNSS) aiding. In this paper the design and performance of a new and computationally efficient pure inertial AHRS, based on extended Kalman filter state estimator, is proposed and experimentally illustrated. The design is based on the explicit incorporation of non-gravitational acceleration into the filter process model and on the adaptive on-line tuning of model parameters, reflecting the actual dynamics of the vehicle. Compared to the state-of-the-art AHRS designs, the proposed AHRS processes all the measurements available, regardless of the actual dynamics of the vehicle. The proposed AHRS is, therefore, suitable for modern high-integrity complex navigation solutions, particularly as a stand-alone back-up solution in GNSS-denied environments.