New Vector Calibration Method for Magnetometer and its Impact on Integrated Navigation System for Low-Cost UAV

Heekwon No, O-Jong Kim, Deokhwa Han, Junesol Song and Changdon Kee

Abstract:	In this paper, we propose a new low-cost vector calibration method for magnetometer can be applied to small low-cost unmanned aerial vehicle (UAV). Calibration method of the magnetic sensor are classified into scalar calibration method and vector calibration method, depending on form of external magnetic field information used in calibration process. Ellipsoid method is typical scalar calibration method, which requires only the magnitude information of the external magnetic field. Calibration accuracy of the ellipsoid method is limited because it fits the magnetic field error in an ellipsoid. While the conventional vector calibration method uses a magnetic field generating device in order to generate specific and known external magnetic field, the proposed method uses the Earth’s magnetic field b y making various changes in orientations of small UAV in flight test. The attitude information is necessary in order to determine the direction of the external magnetic field. The attitude result of the flight test obtained through the GPS/INS integrated n avigation is used in calibration process. The Earth’s magnetic field vector of the international geomagnetic reference field (IGRF) model is converted from the NED coordinate system to the body coordinate system with the reference attitude and this convert ed vector is used as true magnetic vector to calculate the error of the magnetometer. Parameters of spherical harmonics model (SHM) which models the calculated magnetometer error are stored and used to correct the magnetic sensor measurements. To determine the combined effects of the proposed calibration method, the magnetic vector measurements is integrated with GPS/INS navigation system. The navigation performance of ellipsoid method and proposed method is compared under normal and GPS outage conditions. The result shows that the proposed method enhances attitude estimation accuracy in normal GPS condition and exhibits a higher navigation performance during GPS outage.
Published in:	Proceedings of the ION 2017 Pacific PNT Meeting May 1 - 4, 2017 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	1031 - 1047
Cite this article:	No, Heekwon, Kim, O-Jong, Han, Deokhwa, Song, Junesol, Kee, Changdon, "New Vector Calibration Method for Magnetometer and its Impact on Integrated Navigation System for Low-Cost UAV," Proceedings of the ION 2017 Pacific PNT Meeting, Honolulu, Hawaii, May 2017, pp. 1031-1047. https://doi.org/10.33012/2017.15097
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