Drone compass calibration: The ultimate guide

Let's face it; drone compass calibration is not the most exciting topic in the world. But it's a critical process that every drone pilot needs to understand. While the specifics of calibration vary from one drone to the next, there are some general steps that all pilots should follow. These critical steps helps ensure that your drone flies in the right direction and maintains its position correctly.

If you have noticed your drone starts flying unsteadily or circling in flight, doesn't respond well to the remote or flies lower than its usual altitude, it may be time for a compass calibration.

If ignored, this can cause the dreaded flyaway, where your drone suddenly takes off out of control and is impossible to bring back. You want to avoid this at all costs, so it's important to take the time to calibrate your compass correctly.

With this ultimate guide, find out why or when you need one and a step-by-step guide to calibrate your drone’s compass.

Why you should calibrate the drone compass 

Calibration on a drone’s compass is done to adjust its flight system to align with the Earth’s magnetic north instead of its true north. It is important because the earth’s magnetic field is constantly shifting, and calibrating gives the magnetometer (drone’s electronic compass) accurate positioning, which is critical for precise drone control.

The main purpose of calibrating the compass is to get the drone’s magnetic field and subtract it from the total measured magnetic field. When you spin the magnetometer, the surrounding and the drone’s magnetic fields separate because the drone’s compass remains constant while the surrounding rotates. 

When to calibrate your drone

Knowing when to calibrate your drone will save you time and inconvenience, especially in critical situations that need fast actions such as assessing an apartment fire. Since not all cases require a compass calibration, you can start  by first checking: 

Warning signs when calibrating your drone

When the compass is giving extremely poor magnetic data, such as when you are near a strong magnetic field, the UAS’ rear lights will flash red and yellow lights. In such instances the app will show a compass error. However, note that even if you don’t get a compass error, it does not always mean that the drone is calibrated and working correctly.

When you see the light signals, check the settings to know whether you are getting interference from surrounding magnetic fields.  

Compass interference

To confirm compass interference in your Mavic drone, go to the ‘Main Controller Settings’ > ‘Advanced Settings’ > ‘Sensors.’ 

If you are in an area without magnetic influences, the colored bars should be green ( Excellent). If they are red (poor) or a range close to it, move from that area and check whether it changes to the green range. You should calibrate the UAS magnetometer if the bars remain on the red range (poor) or close to it. 

Other than checking for interference, calibrate the drone’s compass:

• Before the first flight to feed the flight system with precise positioning data.
• When you move to a flying location over six miles from your last one.
• When new metallic equipment that may interfere with the drone’s magnetic field has been attached or removed from it, such as a GPS tracker. 
• If your UAS has stayed for more than a month without flying.
• If your drone crashes or flies irregularly, like when it starts circling in flight.
• When the drone loses altitude, or you notice a drop in its usual flight range.
• After traveling with your drone for long because of the vibrations.
• If there is a severe change in the surrounding temperature.

To ensure the compass does not alter its data, try avoiding phone cell towers or high voltage power lines, which will cause electromagnetic interference. While transporting your drone, put it far from the car’s speakers as they may also cause compass failure.

Do not calibrate the UAS compass when you are:

• Close to a building, concrete, or on a stone surface
• Indoors or on the balcony
• On the beach or a boat 
• Near a car or speakers

What you need to calibrate your drone compass

It is easy to calibrate your drone, though you will need the following to avoid failure in the calibration process:

• Ensure you are in an open area with a level surface, where there is a good line of sight.
• Remote control batteries.
• The device programming device (phone, tablet, or laptop)
• A cold climate is favorable to prevent overheating
• If the drone has been running, shut it off for at least fifteen minutes so that it cools down. Do not calibrate the drone when it’s hot.
• Remove the propellers and the gimbal guard.

Step-by-step guide on how to calibrate a drone

Below are the steps needed to calibrate your drone and ensure its smooth operation:

Compass calibration

1. Power on the drone’s transmitter and ensure the drone is fully charged.
2. Using your controller, tap ‘Aircraft Status Bar’ and choose the' calibrate' option.
3. The drone and remote lights should be yellow (for most brands). Hold the drone horizontally to the ground and spin it horizontally until one of its lights turns green.
4. Hold the drone and rotate it vertically to the ground until the next light turns green.
5. If there is an error in the calibration process, you will see a red flashing light. Start the process anew.

IMU calibration

An IMU is a circuit that controls the pitch and roll in a drone to keep it flat and level. The IMU might also cause your drone to fly unsteadily. To calibrate the IMU:

1. Put the drone on a flat surface, power up with the legs stretched out, and face it to the left.
2. Open the iFly app > Safety file > IMU calibrate button
3. Place the drone on its side, facing the right, with the top facing you. Hold it for some seconds while it calibrates.
4. Next, keep the drone straight up and as still as possible as it calibrates.
5. Last, place the drone upside down as it faces the right. Hold it and wait for it to finish calibrating. It will state, ‘calibration complete.’ 

Drone calibration applications

If your drone has the compass calibration app, the instructions are:

1. Select the iFly app > Safety button > Compass calibrate button > Start button
2. The instructions will be to rotate the drone 360 degrees horizontally, I.e., rotate the drone two or three times counterclockwise. Stay in the same spot with no movements, then move the drone 360 degrees, stopping when the app says it has calibrated.
3. Rotate the drone 360 degrees vertically till it faces right. Rotate the drone downwards towards the ground two to three times until it has been calibrated.

FAQs

What affects the drone compass accuracy?

The drone compass always gets interference from magnetic fields caused by objects such as cars, wire fences, rebar reinforced concrete, and glass top outdoor tables. These and other magnetic fields affect and tune it, causing inaccuracy. 

Do you have to calibrate a drone every time?

You need to calibrate your drone every time you fly it in a new location or when there is a magnetic field interference. However, some specialists argue that doing it too often might cause damage. 

What happens if you don’t calibrate the drone?

If you don’t calibrate your drone, it will crash after flying, or you might not be able to control and fly it.

Conclusion

Calibrating your drone compass is relatively easy and necessary to ensure your drone functions appropriately. Follow this guide to ensure your drone’s magnetometer always has accurate data through a DIY calibration.