How can I measure black line width using a robot and QRB1134 sensor?

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Discussion Overview

The discussion revolves around measuring the width of a black line (0.5 inch) using a robot equipped with a QRB1134 sensor and an analog/digital converter (ADC). Participants explore the necessary procedures, sensor capabilities, and the integration of components like microcontrollers in the measurement process.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant seeks guidance on measuring line width with a robot, mentioning the use of a QRB1134 sensor and ADC.
  • Another participant questions the vagueness of the initial inquiry, asking for details about the robot's capabilities, the type of sensor, and the microcontroller used.
  • The original poster clarifies that the robot operates based on commands and controls motor speeds using pulse width modulation (PWM), and describes the QRB1134 as a photo transistor.
  • The original poster considers whether to calculate the robot's speed or use PWM directly to measure the line width.
  • One participant suggests conducting experiments to correlate PWM percentage with robot speed for accuracy and recommends ensuring the robot reaches speed before crossing the line.
  • Another suggestion includes adding an additional opto sensor on the wheel rim to count markings while the robot runs over the line.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and propose different methods for measuring line width, indicating that multiple approaches are being considered without a consensus on the best method.

Contextual Notes

The discussion lacks specific details about the robot's design and the precision of the measurements, as well as the assumptions regarding the relationship between PWM and speed.

brad sue
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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.
 
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brad sue said:
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.

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)?
 
berkeman said:
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)?

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
 
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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