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Thread: Placement of Digital Compass

  1. #1
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    Placement of Digital Compass

    I just got my Devantech Compass for Christmas, and my question is, does it mater if the compass is mounted in the center of the bot, or can it be mounted further out? I know it can't be mounted near metal or magnetic interference, which is what it might not be possible to mount it in the center of the bot, I just want to know if it will effect it's accuracy or anything.

    Thanks, Connor

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    Re: Placement of Digital Compass

    Away from anything is actually ideal. It needs to be as far away from servos and motors (as you guessed) as practical because they generate magnetic fields.

    If you think about using a compass - it always points north. If you hold it out in front of you, tuck it into your body, or hold it out to the side, as long as your body is oriented in the same direction you'll be facing magnetic north.

    It does need to be as flat and level as possible. Tipping a compass, even a damped electronic compass, messes-up any readings. If you think about it - it's trying to move to point THROUGH itself rather than toward the horizon. No matter what, it's going to try to point at the magnetic pole.
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    Re: Placement of Digital Compass

    Thanks for that explanation Adrenlynn, I also wanted to know where is the best placement for a compass. What would we do without you.
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    Re: Placement of Digital Compass

    Someone else would answer.
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    Re: Placement of Digital Compass

    Cables or wires that are power lines which can come from a motor or a servo are bad as well. As current follows thru a wire it will create a small magnetic field around it as well. It could affect your readings.

    Not as much as a motor or servo. But still not great.

    Paul

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    Re: Placement of Digital Compass

    Agreed - but most digital compasses (I can't think of one I've seen otherwise) are pretty filtered against the super-low-level EMI. As long as the cables are short and twisted helps cancel the fields too. I prefer putting mine up on a mast and just eliminating any questions. Another thing most people don't think about - putting it on anything magnetically inclined is bad form too. I tend to make my platform out of aluminum or plastic. Little things will gotcha like chain-drives - metal on metal creating EMI. Or using steel pop-rivits with a steel frame - the flex creates mad EMI.
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    Re: Placement of Digital Compass

    Quote Originally Posted by Adrenalynn View Post
    Someone else would answer.
    Although that may be true ... your answers are the best

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    Re: Placement of Digital Compass

    Well, maybe, but I neglected to note that some of the digital compasses are "tilt compensated" - they won't work at tooo steep an angle, but their better'n analog.
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    Re: Placement of Digital Compass

    I'm using the Devantech Compass, no tilt compensation.. Might make a simple gimble system... The bot might tilt's forward/after a degree or two ..

    Thanks, Connor.

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    Re: Placement of Digital Compass

    You should be ok without the gimble, it should smooth (average) itself out ... I am assuming a walking gate is what you are concerned with?

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