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YouTube video on line following

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  • YouTube video on line following

    I have posted a video called "Following a Line during the Autonomous Period with Blocks Programming" at https://youtu.be/B6jlUCfCcxs
    Let me know if you have questions or comments.

  • #2
    Since posting this video I have done some more test. The REV color sensor is very sensitive to its distance from the mat. Slight increases or decreases in distance from the mat will change the percentage light detected. To get a good range of readings that distinguish the mat from colored tape on the mat, you may need to adjust the sensor up or down.

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    • #3
      We tried following your program and using the "color calibration" opmode to test the sensor and it isn't giving us accurate readings despite moving it up and down to various distances from the floor. Regardless of distance, it fluctuated wildly on all values (hue, etc.) and says the color is red or orange usually when it is either on the white floor, brown paper or black tape. Is there a way to solve this color calibration issue? Also, how would one need to modify the code to follow a black line on a lighter background (brown or white background)? We are using Tetrix motors, Moto G4 phones and we have a REV robotics sensor.

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      • #4
        Originally posted by abondspxrobotics View Post
        We tried following your program and using the "color calibration" opmode to test the sensor and it isn't giving us accurate readings despite moving it up and down to various distances from the floor. Regardless of distance, it fluctuated wildly on all values (hue, etc.) and says the color is red or orange usually when it is either on the white floor, brown paper or black tape. Is there a way to solve this color calibration issue? Also, how would one need to modify the code to follow a black line on a lighter background (brown or white background)? We are using Tetrix motors, Moto G4 phones and we have a REV robotics sensor.
        Regarding your second question: In principal, to following a black line on light background, you would reverse the logic so that you would turn toward the line when the reading increased (go lighter) and turned away from the line when the reading decreased (got darker). That said, following a black line on a dark grey mat may not be technically feasible.

        Turning turn to your first question, it is quite difficult to use Red, Green and Blue values to determine what color something is because greys and browns are a mix of these three colors and so are yellow, purple, etc. I recommend you convert the RGB sensor values to Hue, Value and Saturation. See the following two videos:
        (1) https://youtu.be/iQufRF1HFRc
        (2) https://youtu.be/uSEEO3_JVTI

        Finally, the LightDetected value from the REV sensor should be fairly stable when the sensor is at a fixed distance from the floor. What range of values are you getting for the FTC mat and for white tape?

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        • #5
          There is a new version of the Line Following video posted at https://youtu.be/V_DsxAZvY5c

          ...Bruce

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