Metrological Validation of Pixhawk Autopilot Magnetometers in Helmholtz Cage

Abstract

The use of drones is very extended for multiple applications. Some of them impose attitude and navigation requirements that need appropriate measurements. Pixhawk is an open-source autopilot used on board drones that includes a magnetometer as part of its inertial measurement unit. A testing facility based on a Helmholtz cage is used to evaluate the metrological features of different magnetometer units. The first test induces a magnetic field rotation around six different Pixhawk magnetometers, simulating changes in attitude and course for a drone. The data show a standard deviation higher than 250 mG, in comparison with the standard deviation of 30 mG in the standard gaussmeter model HMR2300. The second test is focused on the stability of the magnetometer, where the Helmholtz cage simulates a certain flight altitude and course. Values obtained from Pixhawk magnetometers range between 25 mG and 116 mG for the highest peak-to-peak magnetic field amplitude, while the standard gaussmeter range is only between 1.3 mG to 5.4 mG. Considering these results, it is possible to determine the limitations of the Pixhawk autopilot magnetometer, both in terms of manufacturing tolerances and measuring stability. Therefore, users should be very careful when using this type of autopilot in professional applications that require precision and safety.

Keywords

• magnetometer
• drone autopilot
• metrology
• Helmholtz cage