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Arduino concept help

dbikelink

I am new to using Arduino and am planning my first project.  I would like some feedback to determine if my thoughts are possible.  I would like to use a rotary encoder to measure the length distance of a rotating object (using a wheel on the encoder).  My question is if there is a way for the Arduino to input that recorded length measurement within the sketch as a "calibration value" of sorts to then make further calculations?

 

Thanks for the help

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    Perhaps keep in mind that your measurement accuracy will depend on the type of encoder used and the diameter of the wheel attached to it.

     

    An incremental encoder will typically give you a number of pulses per revolution. Some low cost ones will only give you  around 12 - 24 pulses per 360degrees of rotation  (30 - 15 degrees between pulses) which may not be accurate enough for your application. They are designed more for inc/dec type control input e.g.:

    https://cdn-shop.adafruit.com/datasheets/pec11.pdf

     

    You can increase the number of pluses per revolution by inserting a gearbox on the input but perhaps also keep in mind there will be a limit to the speed that you can reliably read the pulses at.

     

    Depending upon your application you may be able to use a potentiometer attached to an analogue input on the Arduino to improve accuracy at a lower cost, although this will typically limit you to around 270 degrees of rotation without using mechanical linkages to reverse the direction of the pot every 180 degrees.

     

    As for calibration aspect - you just need to record the number of pulses from the encoder for a known rotation distance of the wheel and as Doug says, a start/stop button could be used.

     

    There is some information on using encoders with Arduino here which may be worth a read:

    https://playground.arduino.cc/Main/RotaryEncoders

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  • 0

    Perhaps keep in mind that your measurement accuracy will depend on the type of encoder used and the diameter of the wheel attached to it.

     

    An incremental encoder will typically give you a number of pulses per revolution. Some low cost ones will only give you  around 12 - 24 pulses per 360degrees of rotation  (30 - 15 degrees between pulses) which may not be accurate enough for your application. They are designed more for inc/dec type control input e.g.:

    https://cdn-shop.adafruit.com/datasheets/pec11.pdf

     

    You can increase the number of pluses per revolution by inserting a gearbox on the input but perhaps also keep in mind there will be a limit to the speed that you can reliably read the pulses at.

     

    Depending upon your application you may be able to use a potentiometer attached to an analogue input on the Arduino to improve accuracy at a lower cost, although this will typically limit you to around 270 degrees of rotation without using mechanical linkages to reverse the direction of the pot every 180 degrees.

     

    As for calibration aspect - you just need to record the number of pulses from the encoder for a known rotation distance of the wheel and as Doug says, a start/stop button could be used.

     

    There is some information on using encoders with Arduino here which may be worth a read:

    https://playground.arduino.cc/Main/RotaryEncoders

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