I am trying to use an APM 2.6 on a Powerwheels jeep with a linear actuator to control the steering.  I am trying to go through the calibration wizard in Mission Planner with the APM disconnected from the Powerwheels jeep.  Not doubt you can understand rotating through 6 degrees of motion is a bit tough if I had to have the jeep, APM and radio receiver all connected at the same time.  

My attempted alternative was to rotate the APM by itself and then connect the actuator and receiver after the rotating step.  Unfortunately the APM disconnects from Mission Planner when I start connecting the radio and receiver.

Any thoughts?

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  • Thanks for that. I've been going crazy trying to figure out how to calibrate my large rover. No way to do it with live. Thanks Chris.

  • You can't rotate the APM on its own (or on a small board) because calibration is to take into account the surrounding fields caused by the rover itself.

    • Developer

      Hi Ben.  You will get a better calibration if you rotate the APM within a powered vehicle however rotating it outside of the vehicle is much better then not doing it at all.

      Thanks, Grant.

  • Developer

    Hi.  Setting COMPASS_LEARN will calibrate the compass but you still need to calibrate the Accels.  What your doing is the correct way for vehicles you can't physically move i.e. power the APM, do the rotation dance and then install the APM into the vehicle.  However, once installed in the vehicle you should also do the "Calibrate Level" process as well.  This is a 1 axis calibration and doesn't require the vehicle to move - only to be level.

    If you try that and still have problems then please post some logs and we will have a look.

    Thanks, Grant.

    • Thanks for the guidance.  Now I need to find time to try it.  

    • When I fired up my rover, the mission planner showed its direction to off by more than 180 degrees. After some simple driving around, the orientation started to resemble the rover. Way cool.

      Thanks for clarifying these steps


  • you could (use a small board or something) hook/wire everything up off the rover on its own like it was on a smaller unit that's easy to manipulate for all the calibrations then install in your rover

  • 3D Robotics

    I have the same problem (go-kart) and the solution is to set the rover to learn the offsets as you drive around. Set COMPASS_LEARN to 1 and drive in circles for a few minutes. That should do it.


    • Much appreciated.  Will give that a go.

    • Admin

      Nice tip Chris, though you probably want to stay away from a surface that has buried rebar or overhead high tension transmission lines.


      Tom C AVD

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