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continuous rotation potentiometer? — Parallax Forums

continuous rotation potentiometer?

ArchiverArchiver Posts: 46,084
edited 2003-11-20 23:34 in General Discussion
Hello, does anyone know how to measure the position of a continuously
rotating wheel? Do I use a multi-turn potentiometer for that, and if
so, what's a good way to link the wheel to the pot? You can e-mail
nathanchronister@y... instead of posting on the group if you
like. Thank you for any suggestions.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-11-20 23:15
    If you have gears, you can use gear-tooth sensor like this one:

    http://www.allegromicro.com/sf/0645/index.asp

    Nick
  • ArchiverArchiver Posts: 46,084
    edited 2003-11-20 23:33
    One way is to use cheap mouse "innards" and read that. See
    http://www.al-williams.com/pak11.htm and http://www.al-williams.com/gp5.htm.
    You can also use the PAK-VI or GP-2 but they aren't optimized for that kind
    of service.

    Regards,

    Al Williams
    AWC
    http://www.al-williams.com


    >
    Original Message
    > From: nathanchronister [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=RhTeFvjTCZr5fwLlU9bfQttPCfonoHMhICKhAgUyQJwo_2oR0piT6Rx0edDizgEGTibVU7e-ePL6pNlxnz4RIIviXw]nathanchronister@y...[/url
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    > Subject: [noparse][[/noparse]basicstamps] continuous rotation potentiometer?
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    > Hello, does anyone know how to measure the position of a continuously
    > rotating wheel? Do I use a multi-turn potentiometer for that, and if
    > so, what's a good way to link the wheel to the pot? You can e-mail
    > nathanchronister@y... instead of posting on the group if you
    > like. Thank you for any suggestions.
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  • ArchiverArchiver Posts: 46,084
    edited 2003-11-20 23:34
    The easiest way is to use some sort of an encoder.

    Do you need to know how fast (RPM's), angular displacement, direction, or
    just that it is spinning?

    Different approaches to all the above sensory input.

    A magnet on the wheel with a hall sensor will give you RPM. Count the pulses
    over time.
    An Absolute Encoder will give angular displacement of the wheel. These are
    expensive but output a code of the rotational angle of the wheel.

    An A-B Differential Encoder will give you speed, direction and, if referenced
    to an index mark, angular displacement. More expensive than a magnet/hall
    sensor but cheaper than an Absolute Encoder.

    Or you could use a cloths pin and clip a playing card to the frame so it
    sticks into the spokes and if it is making noise, the wheel is spinning.

    I am not trying to be a wise cracker but, without more information it is hard
    to know where you want to go (Pun intended).

    Its like asking how much a car costs, or how heavy is a tank of water.

    Thanks,
    Alan Bradford
    Plasma Technologies





    In a message dated 11/20/2003 5:53:05 PM Eastern Standard Time,
    nathanchronister@y... writes:
    Hello, does anyone know how to measure the position of a continuously
    rotating wheel? Do I use a multi-turn potentiometer for that, and if
    so, what's a good way to link the wheel to the pot? You can e-mail
    nathanchronister@y... instead of posting on the group if you
    like. Thank you for any suggestions.


    [noparse][[/noparse]Non-text portions of this message have been removed]
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