Abstract
Magnetometers provide compass information, and are widely used for navigation, orientation and alignment of objects. As magnetometers are affected by sensor biases and eventually by systematic distortions of the Earth magnetic field, a calibration is needed. In this paper, a method for calibration of magnetometers with three Global Navigation Satellite System (GNSS) receivers is presented. We perform a least-squares estimation of the magnetic flux and sensor biases using GNSS-based attitude information. The attitude is obtained from the relative positions between the GNSS receivers in the North-East-Down coordinate frame and prior knowledge of these relative positions in the platform’s coordinate frame. The relative positions and integer ambiguities of the periodic carrier phase measurements are determined with an integer least-squares estimation using an integer decorrelation and sequential tree search. Prior knowledge on the relative positions is used to increase the success rate of ambiguity fixing. We have validated the proposed method with low-cost magnetometers and GNSS receivers on a vehicle in a test drive. The calibration enabled a consistent heading determination with an accuracy of five degrees. This precise magnetometer-based attitude information allows an instantaneous GNSS integer ambiguity fixing.
Highlights
A precise attitude information is essential for numerous applications, e.g., for navigation, for flight control and for constructions
The attitude is obtained from the relative positions between the Global Navigation Satellite System (GNSS) receivers in the North-East-Down coordinate frame and prior knowledge of these relative positions in the platform’s coordinate frame
The calibration can be performed with three Global Navigation Satellite System (GNSS) receivers (e.g., GPS, Galileo, GLONASS, Beidou) being placed on the same platform as the magnetometer
Summary
A precise attitude information is essential for numerous applications, e.g., for navigation, for flight control and for constructions. Magnetometers provide attitude information globally but are affected by sensor biases and measurement errors. The latter ones can be systematic due to metallic environment and/or stochastic due to measurement noise. Sensor biases and systematic errors can be removed by calibration. The calibration can be performed with three Global Navigation Satellite System (GNSS) receivers (e.g., GPS, Galileo, GLONASS, Beidou) being placed on the same platform as the magnetometer. Satellite navigation enables the determination of the relative position between both GNSS receivers in a local coordinate frame, e.g., the North-East-Down (NED) frame. The obtained relative position is related to the prior knowledge of the relative position in the body-fixed frame to obtain the platform’s attitude
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