Accelerometer calibrations

The IMU is embedded in the flight controller and includes a gyroscope and an accelerometer, which respectively produce angular rate (in degrees/second) and linear acceleration measurements (normalized to gravitational acceleration at sea level \(g = 9.81 \frac{m}{s^2}\)).

Fig. 118 Sensors tab in Cleanflight Configurator showing Gyroscope and Accelerometer readings

Calibrating the accelerometer provides the “zero” plane around which the Flight Controller will stabilize the drone during flight, and is a procedure that should be repeated before each flight.

Method 1: calibration through CleanFlight

1. Connect the Flight Controller to the base station using the micro USB cable.

2. Navigate to the Setup page

3. Place the drone on a (very) flat surface

   Attention

   Make sure the drone is level on the flat surface.

4. Click on Calibrate Accelerometer

   Warning

   Do not move the drone while the calibration is in progress or it will invalidate the calibration.

5. Wait for a few seconds. A successful outcome will produce a “reset” of pitch and roll measurements and the rendering of the drone’s attitude will show a level condition.

Fig. 119 Calibration procedure

Moreover, a message will appear on the top left of the CleanFlight interface saying Accelerometer calibration finished.

Method 2: calibration through the Dashboard

The same result as above can be obtained by connecting to the Dashboard instead of directly hard-wiring the Flight Controller to the base station.

1. Connect to the Dashboard (First connection)

2. Navigate to the Robot > Mission Control page

3. Find the IMU - Orientation mission control block

4. In the top right corner of this block, find and click on the Calibrate IMU button.

   • The data streaming will freeze for a few seconds while the calibration is undergoing, and it will resume once the calibration is complete.

Fig. 120 Calibration of the IMU through the Duckiedrone dashboard

Resetting Yaw offset

The IMU calibration “resets” roll and pitch values to zero, but not the yaw.

Note

This part is optional and not strictly needed to have stable flight.

Zeroing the yaw defines the new “forward” direction of the drone, and it can be done through the CleanFlight interface.

1. Connect the Flight Controller

2. Navigate to the Setup page

3. Click on Reset Z axis, offset

4. A successful outcome will:

   1. show a new offset value on the reset button itself

   2. the rendering will show the drone oriented towards the new zero.

Fig. 121 Drone yaw calibration procedure