This article shows how to perform basic accelerometer calibration (using Mission Planner).
Accelerometer calibration is mandatory in ArduPilot.
Accelerometer calibration cannot be performed while vehicle is armed
If the board is mounted in a non-standard orientation (i.e. arrow is not pointing forward) then please ensure the AHRS_ORIENTATION is properly set before doing the accelerometer calibration.
Under Setup | Mandatory Hardware, select Accel Calibration from the left-side menu.
Click Calibrate Accel to start the calibration.
Mission Planner will prompt you to place the vehicle each calibration position. Press any key to indicate that the autopilot is in position and then proceed to the next orientation.
The calibration positions are: level, on right side, left side, nose down, nose up and on its back.
- It is important that the vehicle is kept still immediately after pressing the key for each step. This is more important than getting the angle exactly right, ie. left being 90deg to horizontal,etc. Except for the first “LEVEL”, the positions can be within 20 degs of being exact. Being still in each position as you press the key is much more important.
- You may need to calibrate the board before it is mounted if the size/shape of the vehicle makes this difficult.
- The level position is the most important to get right as this will be the attitude that your controller considers level while flying.
For planes, often the optimum “level” position is actually done with the nose raised a few degrees (but the wings perfectly level). This is explained in the diagrams below. Most planes fly with a few degrees of Angle of Attack (AOA)and while many planes will have some Angle of Incidence built in, some do not, and some need a little higher AOA to fly at lower cruise speeds. If the level step of calibration is done with the plane’s fuselage line level, then first flights will be safe, but cruise may be a bit fast. You can either set a few extra degrees nose up when doing the level step of calibration, or decide after first flights if AOA needs to be increased for your desired cruise speed/throttle. If so, then you may redo the level only step using the
Calibrate Levelbutton on the page.
this can only change the difference between the autopilot’s plane and “level” by 10 degrees maximum. If more is needed (in the case that the autopilot is mounted slightly downward, for example), then you can use TRIM_PITCH_CD to alter the AOA manually.
Proceed through the required positions ,using the the Click when Done button after each position is reached.
When you’ve completed the calibration process, Mission Planner will display “Calibration Successful!” as shown below.
If your autopilot has a built-in IMU heater, then it is recommended that the IMU Temperature Calibration also be done.
Video demonstration (Copter)¶
Video demonstration of accelerometer calibration. This is for an older version of Copter/Mission Planner, but is useful as an example of how you might hold a Copter.