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Width of a black line -robot

  1. Oct 16, 2008 #1
    Hi,
    I would like to measure black line width (width of 0.5 inch)with a robot.
    I don't know how to do it.
    I use a QRB1134 sensor and the Analog/digital converter.
    please can someone guide me on the procedure for this please?
    C.
     
  2. jcsd
  3. Oct 17, 2008 #2

    berkeman

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    Staff: Mentor

    Your question is kind of vague. You mention a robot -- what are its capabilities? You mention a sensor -- what kind of sensor is it? You mention an ADC, but no mention of a microcontroller (uC) or any other circuitry for operating the ADC and getting results out of it. What is your level of expertise with these things (robots, ADCs, uCs)? Are you actually building this, or just doing a paper design? What course is this for (what year)?
     
  4. Oct 17, 2008 #3
    Sorry about that!
    So far the robot is just running according certain command : turn left , right etc.. The motor speeds are controlled via the pulse width modulation (PWM).
    The sensor is the QRB1134. It is a photo transistor.

    The MCU I used is the freescale MC9S1C32 and it has a ADC integrated. so I have no more circuitry to add but connecting the line sensor and a pull up resistor. I have worked with the ADC before but not much.

    To measure the width of a black line , I think I need to compute the speed of the robot and the time the robot runs 0.5 inch. Do you think I must calculate the speed or just use the PWM?
    If not how to have a precise value of the speed?

    Thank you
     
  5. Oct 20, 2008 #4

    berkeman

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    Staff: Mentor

    You can do some experiments to see if you can correlate the PWM percentage with robot speed to within whatever your target accuracy is. Be sure that the robot is up to speed before running over the line, however.

    Alternately, you could put another opto sensor on a wheel rim, and put little lines on the rim that you can count at the same time you are running over the black line...
     
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