Magnetometers are essential for precise navigation, geophysical exploration, and motion tracking, but their accuracy depends on proper Calibration. Various factors, including sensor imperfections, environmental interferences, and device orientation, can introduce errors that degrade performance. Choosing the appropriate calibration method ensures that your magnetometer provides reliable and accurate measurements.
Explore the most common magnetometer calibration techniques, from basic offset corrections to advanced machine-learning-based solutions. Whether working with a high-precision inertial navigation system or a compact consumer-grade device, understanding the trade-offs between different methods can help optimize performance for your specific application.
1. 3D Calibration
Application: The 3D Calibration is designed for carrier objects (typically aerial or marine) operating in full heading, pitch, and roll ranges. A possible application using this calibration method is bathymetric surveillance.
Calibration Method: At this Calibration, the carrier object should be rotated in all these ranges. The object should be rotated in full azimuth, pitch, and roll ranges during the INS data accumulation. For example, the object is rotated in the horizon plane (the Z-axis is up) with periodical stops about 90 degrees for tilting in pitch and roll. After a 360° rotation, the object with the INS is turned over (the Z-axis is down), and the procedure described above should be repeated. During this Calibration, the pitch and roll angle range must change as much as possible.
Reference: Section 6.8.1 of INS ICD
2. 2D-2T Calibration
Application: The 2D-2T calibration is designed for objects that operate in full azimuth range but with a limited range of pitch and roll angles, such as indirect fire control.
Calibration Method: This calibration procedure involves a few complete 360° rotations of the object in azimuth with different pitch angles. After sending the start command to the INS, rotate the object in azimuth with approximately constant pitch and roll. This rotation must include one or more full 360-degree turns. Please correct the time required for such rotation in the «Time of data accumulation» field of the message (Table 6.88) to provide the necessary rotation.
Reference: Section 6.8.6 of INS ICD
3. 2D Calibration
Application: The 2D Calibration is designed for carrier objects that operate in full azimuth range but with small pitch and roll angles (not more than a few degrees), such as land vehicle applications.
Calibration Method: This calibration procedure involves a full 360° rotation of the carrier object in azimuth. The pitch and roll angles must be near zero during this rotation. After sending the start command, rotate the carrier object in azimuth with pitch and roll angles as close to zero. This rotation must include one or more full 360-degree turns. Please correct the time required for such rotation in the «Time of data accumulation» field of the message (Table 6.88) to provide the necessary rotation.
Reference: Section 6.8.9 of INS ICD
4. VG3D Calibration
Application: The VG3D calibration is designed for carrier objects operating in full heading, pitch, and roll ranges, such as fixed-wing UAVs and aircraft. VG3D calibration is similar to 3D Calibration but allows for more straightforward rotation than is necessary for 3D Calibration.
Calibration Method: During the INS data accumulation, the object should be rotated in full azimuth range and maximum possible pitch and roll ranges. Allowed object motion should be agreed with Inertial Labs.
Reference: Section 6.8.5 of INS ICD
5. On-the-Fly VG3D Calibration
Application: Since firmware version 2.6.2.2, the INS has provided on-the-fly VG3D calibration. It allows the Calibration of the INS unit during INS ordinary operation without interrupting INS navigation data calculation and output. This could be possibly used for drone payload applications.
Calibration Method: After sending the start calibration command to the INS, the carrier object with INS unit should be rotated in full azimuth range with maximum possible pitch and roll ranges. For example, an airplane should perform at least two full 360° coordinated turns (on the right and the left, figure eight pattern) with maximum roll angles.

Reference: Section 6.8.12 of INS ICD