A Constrained GPS/INS Integration Based on Rotation Angle for Attitude Update and Dynamic Models for Position Update

Ezzaldeen Edwan, Stefan Knedlik, Junchuan Zhou, Otmar Loffeld

Abstract:	In this paper, we present a constrained fusion scheme to integrate the GPS measurements of position and velocity with the inertial measurements of acceleration and angular velocity. The basis for this integration is the ground alignment method for attitude and heading determination. The advantage of using this method is having a bounded error in the estimated roll and pitch angles without the need for extra measurement of them. The time update of the position, velocity and acceleration is performed using a proper dynamic or kinematic model while attitude update of the direction cosine matrix DCM is performed using angle rotation vector. The integration algorithm is implemented using an extended Kalman filter. Ground alignment relies on measuring the gravity vector in the body frame and on the knowledge of the gravity vector in the local navigation frame. For static or low dynamic scenarios, the tri-axial accelerometers operate effectively in determining both roll and pitch angles. Gyro compassing for alignment can be used if the quality of gyros permits, otherwise heading information can be derived from GPS (velocity or multi-antenna system) or tri-axial magnetometers). Unlike the traditional GPS/INS integration where the accelerometer outputs are used to update acceleration expressed in the navigation frame in the process part, we will use it in the measurement part of the EKF to measure directly the DCM elements and acceleration expressed in the local navigation frame.
Published in:	Proceedings of the 2009 International Technical Meeting of The Institute of Navigation January 26 - 28, 2009 Disney's Paradise Pier Hotel Anaheim, CA
Pages:	736 - 743
Cite this article:	Edwan, Ezzaldeen, Knedlik, Stefan, Zhou, Junchuan, Loffeld, Otmar, "A Constrained GPS/INS Integration Based on Rotation Angle for Attitude Update and Dynamic Models for Position Update," Proceedings of the 2009 International Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2009, pp. 736-743.
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