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Onboard Sensors' Re-calibration

Introduction

The Vertex One contains multitude of sensors, like accelerometers and a magnetometer which in certain cases may require re-calibration.

Accelerometer

Accelerometer Re-Calibration Indication

Accelerometer measures acceleration. As this gravitational acceleration is slightly different across the Earth, the sensor might have slight offsets in the measurement. Consider re-calibrating the accelerometer when you are:

  • Operating the Vertex more than 100 km away from the previous calibration (default calibration: Eindhoven, The Netherlands)
  • Experiencing large drifts while flying

Accelerometer Re-Calibration Procedure

Please contact Avular support if you think calibration is required.

Magnetometer

The magnetometer measures magnetic field around Vertex One including earth’s magnetic field. This measurement, in principle like a navigation compass, is one of the sensor inputs to determine the flight orientation of Vertex One.

The measured Earth’s magnetic field is slightly variable depending on the location, while it can also be (locally) disturbed by the presence of:

  1. Large (metallic) structures, e.g. tanks, poles, masts, cranes
  2. Power distribution net, e.g. high-voltage lines
  3. Other electromagnetic fields, e.g. in the proximity of transmitters or broadcasting devices

Depending on the nature of these, the disturbances might cause intermittent orientation readout inaccuracies or a constant readout inaccuracy or a readout drift.

To increase navigation accuracy and offer sensor redundancy the Vertex One contains two magnetometers:

  1. Internal magnetometer (placed in the drone’s body)
  2. External magnetometer (placed on the magnetometer bracket)

Magnetometer Re-Calibration Indication

Re-calibrate the magnetometer when:

  • The Vertex One does not pass the stage of magnetometer initialization after start-up
  • Your drone is experiencing drift in the heading direction
  • Your drone suffers from uncontrollable oscillations, so called 'Toilet bowling' (only occurring in case of outdoor flight using GNSS navigation)
  • The external magnetometer module has been replaced for a new one
  • You are operating the Vertex more than 100 km away from the previous calibration location (default calibration: Eindhoven, The Netherlands)

Caution

Only perform this calibration in a relevant environment (outdoors) without any obvious local disturbances to the earth magnetic field (e.g. away from metallic structures and powerlines).

Caution

Ensure that person performing the re-calibration has by them no devices that might cause disturbance of the magnetic field such as a mobile phone or a watch.

Internal Magnetometer Re-Calibration Procedure

  1. Connect your Vertex One to a computer running Cerebra Lab
  2. Upload the Magnetometer Calibration Model to your Vertex One from the bin list (see Upload Vertex embedded applications).
  3. Power on the Vertex One
  4. Wait for the LED indicators to turn Magenta, indicating it is ready to start.
  5. Rotate the Vertex One 360 degrees around its roll (x-)axis slowly. The LED indicators will start flashing blue to indicate that the calibration data is being collected during the drone’s rotation.
  6. Repeat this process for the pitch (y-) and yaw (z-) axis.
  7. If enough calibration data is collected, the LED indicators start fast flashing blue. If this doesn’t happen, try rotating the Vertex around its diagonal axis or repeat steps 5 and 6.
  8. The LED indicators will go from fast flashing blue to solid blue, to green. Indicating that the calibration parameters are correct, successfully written to the memory and verified respectively.

In case the LED indicators flash red, there is an error that blocks the calibration from being performed. Please restart your Vertex One to try again.

External Magnetometer Re-Calibration Procedure

  1. Connect your Vertex One to a computer running Cerebra Lab
  2. Open Cerebra Lab workspace and go to 'parameters' in the right pane. Set 'Items View' to 'Labelled'.
  3. Set the "external_mount" parameter from 0 to 1 and press 'Send'. Now the external magnetometer will be used for the calibration process.
  4. Upload the Magnetometer Calibration Model to your Vertex One from the bin list (see Upload Vertex embedded applications).
  5. Power on the Vertex One
  6. Wait for the LED indicators to turn Magenta, indicating it is ready to start.
  7. Rotate the Vertex One 360 degrees around its roll (x-)axis slowly. The LED indicators will start flashing blue to indicate that the calibration data is being collected during the drone’s rotation.
  8. Repeat this process for the pitch (y-) and yaw (z-) axis.

In case the LED indicators flash red, there is an error that blocks the calibration from being performed. Please restart your Vertex One to try again.