Line Follower Robot – Competition Edition

This project is an Arduino Nano-based line follower robot built for a competitive event. It uses a QTR 8RC IR sensor array for line detection, a TB6612FNG motor driver, and a Hall effect sensor to trigger tasks via magnets embedded in the track. The robot is designed to complete a series of tasks as per the competition rules.

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Competition Rules & Task Flow

• Track: Solid black, 25mm wide, revealed at the venue. Includes 90° turns, bends, zig-zags, and shapeless sections.

• Tasks are triggered by magnets under the track (detected by Hall effect sensor):

  1. Stop for 5 seconds
  2. Turn on red LED (remains ON until next trigger)
  3. Turn on yellow LED, turn OFF red (yellow remains ON until next trigger)
  4. Turn on green LED (always ON till end), turn OFF red
  5. 360° rotation
  6. Ignore this trigger
  7. Reverse traverse (180° rotation)
  8. Second reverse traverse trigger
  9. Stop the bot permanently

• Mandatory Components: Red, yellow, green LEDs; Hall effect sensor (A3144 or reed switch).

• Scoring: Points for each section, task, and finish. Penalties for hand touches and debugging time.

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Hardware Used

• Arduino Nano
• TB6612FNG Motor Driver
• QTR 8RC IR Sensor Array
• Hall Effect Sensor (A3144, analog out)
• Push Button (for calibration/run)
• 3 LEDs: Red, Yellow, Green (common GND, positive to digital pins)
• 7.4V Li-ion Battery Pack
• Buck Converter (powers Arduino and sensors)
• HC-05 Bluetooth Module (hardware present, but not implemented in current code)

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Circuit Connections

Motor Driver (TB6612FNG):

• AIN1 = D7
• AIN2 = D8
• PWMA = D5
• BIN1 = D9
• BIN2 = D11
• PWMB = D6
• STBY = VCC (hard-wired)
• VCC/GND = Battery

QTR Sensor Array:

• GND/VCC = Buck converter
• IR ON = VCC (hard-wired)
• Sensor 1 = D10
• Sensor 2 = A0
• Sensor 3 = A1
• Sensor 4 = A2
• Sensor 5 = A3
• Sensor 6 = A4
• Sensor 7 = A5
• Sensor 8 = D3

Other:

• Push Button = D13
• Red LED = D12
• Yellow LED = D2
• Green LED = D4
• Hall Effect Sensor Signal = A6

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Usage

1. Upload line_follower.ino to your Arduino Nano.
2. Power on the robot.
3. Press the button to start sensor calibration (robot rotates to calibrate).
4. Press the button again to start line following and task execution.
5. The robot will follow the line and perform tasks as it detects magnets.

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Images

Front View:

Back View:

Side View:

At the Competition:

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Notes

• Current code may have issues with tight corners and 90° turns.
• Bluetooth module is not implemented in this version.
• For best results, tune PID values in code and adapt to the actual track during the allowed modification period.

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Good luck at the competition!