Calibrating the compass in LOGOS GCS
The compass (magnetometer) is a critical sensor for UAVs based on ArduPilot. It is responsible for determining the course, GPS coordinates and flight stability (Loiter, RTL, Auto modes). Incorrect calibration leads to:
- Drone rotation – in position hold mode.
- Navigation errors – the drone is flying in the wrong direction.
- Attitude/FBWA failures – due to data conflict with the gyroscope.
Let's look at how to properly calibrate the compass of our drone in LOGOS GCS.
When compass calibration is necessary?
- First setup of a new UAV – without calibration, the controller receives distorted data about the device's position.
- If the drone is spinning in hovering or autopilot modes.
- Does not hold course in autonomous flight mode.
- Gives errors related to the operation of the compass.
Preparing for calibration
- Avoid magnetic interference - from metal, electronic devices, power lines.
- Connect an additional power source (LiPo battery) to the drone.
- Connect the drone to the computer via USB or telemetry.
- Run the LOGOS GCS program.
- Connect to the drone from the program by selecting the network type "AUTO(SERIAL)".
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Make sure that the satellite communication sensor in the program shows a sufficient number of devices (at least 5).
- Go to "UAV settings" → "Compass".
You do not need to select a compass. The program automatically detects all of them and gives preference to an external compass over the built-in one, when one is available.
The program sends a command to the drone about the calibration completion if the procedure is successful.
How to calibrate the accelerometer in LOGOS GCS?
Calibration
- Set the "Fitness" parameter, which is responsible for the strictness of the calibration (it is enough to select 'Default').
- Click the "Calibrate" button - the first image should be outlined in white.
- Holding the drone in the horizontal plane, rotate it as shown in the 1st image in the program until it is outlined in green color.
- Holding the drone left side down, rotate it as shown in the 2nd image in the program until it is edged in green.
- Continue to change positions and rotate the drone, following the instructions in the images until they are all edged in green and the program confirms successful calibration.
Checking the results
- Connect to the drone via telemetry or USB modems.
- Open the mission planning tab.
- Make sure the compass sensor is showing the correct data.
Common problems and solutions
- Compass not healthy → check the sensor connection, reboot the flight controller.
- The drone is spinning after calibration → interference may be interfering (try again in another location).
- Calibration error → try reducing the calibration severity or calibrating outdoors, away from magnetic influence.
Conclusion
Correct compass calibration is the key to stable operation of GPS modes in ArduPilot. The procedure takes 2-3 minutes, but significantly improves the drone's behavior in autonomous flights. If problems persist, check vibrations, interference, and the physical condition of the sensor.
Tip: For multi-rotor UAVs, it is better to use an external compass mounted on the tripod (as we did) to minimize the influence of electromagnetic fields from the motors and ESC.