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Compass off by 45° in X frame setup, Input_voltage setting in CLI

Posted by Niklas Goddemeier on June 28, 2011 at 8:58am

Hi everybody, as this is my first post. I would like to say thanks to all the people who are working so hard on this project.

While testing the current firmware in an X  frame setup I have noticed an offset of the compass by exactly 45°. I also think that this is the reason why the loitering mode does not work properly and results in circular movements. I think this might be the same issue others might have with the loiter mode.

Is there a parameter I need to change or is this a bug? APM is mounted as described here http://code.google.com/p/arducopter/wiki/AC2_Frame_Assembly

and the MAG is mounted to the shield as described here:

http://code.google.com/p/arducopter/wiki/AC2_Magnetos

Any help on this is highly appreciated.

Another issue that came up is, while using the new APM Board (v1.4) the 5V power supply is connected via a diode (D1) this used to be only the case (v1.2) when using external power. This however results in a voltage of about (4.7v) at the ATMega. While everything still works fine, the analog ref. voltage will be a bit low resulting in wrong AD-conversion. I know there is the “#define INPUT_VOLTAGE 5.0” in the config file.  However, this might be a good parameter to include in the CLI setup menu. Because everything else is working great and can be configured in the CLI.

Keep up the good work,
Niklas

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Tags: apm, compass, input_voltage, offset, v14
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Replies

  • Aleksey Zaitsevsky July 6, 2011 at 5:02am
    I have hexa-plus frame, firmware 2.033. Problem still exist. True north pole must be 45 deg CCW. (maybe I must try to test it in another place?)
  • Aleksey Zaitsevsky June 29, 2011 at 5:15pm
    Same problem (45 deg error) in Hexa_plus configuration. Version 2.029.
  • DaveyWaveyBunsenBurner June 28, 2011 at 1:36pm
    Chris,

    Does the compass code read the frames x or + config? If not that could account for this issue?

    Best

    D
  • 3D Robotics
    Chris Anderson June 28, 2011 at 10:22am
    Please update to the latest code (you can use the Mission Planner to automatically check for new code and load it). There is a new magnetometer that is now being shipped by the DIY Drones store that has the axis differently than the old one. The code has now been updated (thanks to Randy Mackay!) to autodetct which mag you have and adjust the measurement accordingly.
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