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DJI Spark – Compass & IMU

Perhaps the most asked question on Facebook forums . . . how often should I re-calibrate my compass and IMU?

Firstly, let’s explore what these are actually for.

Let’s begin with the compass, this enables the Spark to understand which way it is pointed.

Secondly we have the IMU (Inertial Measurement Unit).

The IMU takes information from the following components in order to understand it’s surroundings and adjust for flight:

  • Barometer – Measures air pressure and therefore determines altitude
  • Thermometer – Measures temperature (the Spark has an operating temperature ranging from 0 to 40 degrees)
  • Gyroscope – Measures orientation and angular velocity
  • Accelerometer – Measures acceleration

Without the IMU the Spark wouldn’t know if it’s going up, down or even how fast it going . . . it would basically be an expensive block with 4 spinning propellers.

How often should I calibrate the compass?

A lot of people say only calibrate when the App prompts you too, but I don’t personally think this is good enough.

The Spark can only detect when the compass is providing extremely poor data, such as when you are near a strong magnetic field. The lack of a warning message in the App does not mean your compass is working and calibrated correctly.

If you load up the DJI Go 4 App and open Menu > Main Controller Settings > Sensors and then click the ‘Compass’ tab you will see a coloured bar.

  • Green (Excellent) – The Spark is in a location away from magnetic influences
  • Red (Poor) – Move the Spark to a different location and check again

Upon calibrating the compass correctly (I’ll cover this later), my recommendation would be to only recalibrate if one of the following were true:

  • You are prompted within the DJI Go 4 App
  • Your Spark is circling unexpectedly in flight
  • Your flight location is over 100 miles from the location where you last calibrated the compass

How do I calibrate the compass?

Firstly, location is everything . . . if you are not in the right place then recalibrating the compass is a pointless task.

  • Move outside
  • Stand away from any buildings, concrete or overhead power lines
  • Stand away from any magnetic metallic objects (cars, speakers etc)

Next, remove all metal from yourself (if you are the person who will be doing the recalibration) . . . here I’m talking about rings and watches mainly.

And now for the actual calibration.

  • Turn on your Spark and accessories as normal.
  • Wait until the Spark is ready to fly.
  • Select CALIBRATE under the Compass heading (Menu > Main Controller Settings > Sensors and then click the ‘Compass’ tab)
  • Confirm solid yellow rear lights on the Spark
  • Pick up the Spark and turn it smoothly and steadily a full 360 degrees until the lights turn solid green
  • Point the front of the Spark straight down and repeat until the lights turn off and resume normal flashing

Note: If for any reason the above is not completed smoothly, restart the process and try again.

How often should I calibrate the IMU?

Recalibrating the IMU is a task that you will, hopefully, not have to undertake very often. My personal recommendation would be only recalibrate if one of the following were true:

  • You have just received / opened your Spark
  • You are prompted within the DJI Go 4 App
  • You have ‘Good’ or ‘Poor’ scores within the IMU screen (Menu > Main Controller Settings > Sensors and then click the ‘IMU’ tab)
  • Your Spark has problems with yaw movements (drifting)
  • Your Spark is changing altitude unexpectedly
  • You have crashed your Spark

Other than the above, personally, I’d leave the IMU alone.

How do I calibrate the IMU?

Once again, location is everything and now it’s time to ensure you have a completely flat surface to work on. By ‘completely flat’ I’m talking about getting a bunch of spirit levels or apps to check first.

Note: Also make sure it is a stable surface and one that won’t move if you accidently ‘nudge’ it

Before we go ahead and do the IMU calibration you firstly should wait until your drone and battery has cooled down to room temperature.

  • Remove all propellers
  • Turn on your Spark and accessories as normal.
  • Wait until the Spark is ready to fly.
  • Select CALIBRATE under the IMU heading (Menu > Main Controller Settings > Sensors and then click the ‘IMU’ tab)
  • Hit ‘Start’ and follow the guide step-by-step (play close attention to the radio buttons in the bottom left of the screen as they are indicators that you can go to the next step)
  • ONLY move when you are prompted (Spark lights flash green)

Note: Yes, you do lean the Spark on the prop motors (it will be slightly angled when you let go)

Note: If for any reason the above is not completed smoothly, restart the process and try again.

. . . and that’s your lot! I hope you find this article helpful.

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