Line Following Robot

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Overview / Introduction

This project demonstrates a line-following robot built using an Arduino UNO and two infrared (IR) sensors. The robot detects the path (usually black line on a white surface) and follows it using logic-based decision-making. It controls two motors through a motor driver module and uses IR sensors to detect the black or white surface below.

Features

• Follows a predefined black line on a white surface
• Real-time direction control using dual IR sensors
• Smart turn left/right or stop based on IR feedback
• Customizable speed settings for forward and turn
• Simple logic and easy-to-understand code

Hardware Components

• Arduino UNO (1x)
• IR Sensor Modules (2x)
• L298N Motor Driver (1x)
• DC Motors (4x)
• Robot Chassis (1x)
• Wheels (4x)
• Jumper Wires
• Battery Pack (1x)

IR Sensors (Infrared Sensors)

Infrared (IR) sensors are the primary components used for line detection in this robot. Each IR sensor module consists of:

• IR LED (Emitter) — Emits infrared light onto the surface.
• Photodiode/Phototransistor (Receiver) — Detects the reflected IR light.

Working Principle:

• White surface reflects IR light → Photodiode detects it → Output is LOW
• Black line absorbs IR light → Photodiode detects nothing → Output is HIGH
• This difference in reflection allows the robot to detect where the black line is and respond accordingly.
• If both sensors see white → go forward.
• If left sees white and right sees black → turn left.
• If right sees white and left sees black → turn right.
• If both see black → stop.

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L298N Motor Driver

The L298N Motor Driver Module is used to control the two DC motors of the robot. It acts as an interface between the low-power Arduino and the high-power motors.

Features:

• Can control the direction and speed of two DC motors.
• Accepts PWM (Pulse Width Modulation) signals from Arduino to adjust motor speed.
• Has two enable pins (ENA, ENB) and four control pins (IN1, IN2, IN3, IN4) connected to the Arduino.

Working:

• ENA / ENB: Used to control the speed of motors via analogWrite().
• IN1/IN2 (for Motor A) and IN3/IN4 (for Motor B): Used to control motor direction via digitalWrite().

Example:

digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);

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How to Charge Lithium-Ion

What You Need:

• TP4056 charging module (with or without protection circuit)
• Lithium-Ion battery (typically 3.7V, like an 18650 cell)
• Power source (5V via USB cable or 5V adapter)

Wiring Connections

TP4056 Pin	Connects To	Description
BAT+	Battery Positive (+)	Connect to battery's positive terminal
BAT-	Battery Negative (–)	Connect to battery's negative terminal
IN+	5V Power Positive	USB VCC or 5V adapter
IN-	5V Power Ground	USB GND or adapter GND
OUT+	Output Positive (Optional)	Same as BAT+ if present
OUT-	Output Negative (Optional)	Same as BAT– if present

Charging Status (LED Indicators)

• 🔴 Red LED ON → Charging
• 🟢 Blue/Green LED ON → Fully Charged (approx. 4.2V)

TP4056 Specifications

• Input Voltage: 4.5V – 5.5V (recommended: 5V)
• Charging Cut-off Voltage: 4.2V
• Max Charging Current: 1A (default, adjustable by changing onboard resistor)

Charging Steps

1. Connect BAT+ and BAT- to the Lithium-ion battery terminals.
2. Connect IN+ and IN- to a 5V power supply (USB or adapter).
3. Observe LED indicators:
   • Red = Charging
   • Green/Blue = Fully Charged
4. Disconnect power once fully charged (unless using protected module).

Safety Tips

• Never leave charging unattended.
• Use only genuine 3.7V Li-ion batteries.
• Avoid short circuits on BAT terminals.
• Do not reverse polarity — it can damage the module and the battery.
• Use TP4056 with protection for safer charging and discharging.

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Software Requirements

• Arduino IDE
• USB drivers for Arduino
• Serial Monitor (for debugging)

Pin Configuration

Component	Arduino Pin
IR Left Sensor	A1
IR Right Sensor	A0
Motor Left Enable	5 (ENA)
Motor Right Enable	3 (ENB)
Motor Left Pin 1	11
Motor Left Pin 2	10
Motor Right Pin 1	9
Motor Right Pin 2	8

Decision Making Logic

The robot makes decisions based on the IR sensor input:

• Both sensors LOW → Move Forward
• Left LOW, Right HIGH → Turn Left
• Left HIGH, Right LOW → Turn Right
• Both HIGH → Stop

Function Descriptions

• moveForward() — Moves robot forward by setting both motors in forward direction.
• turnLeft() — Rotates robot left by reversing the right motor and driving the left forward.
• turnRight() — Rotates robot right by reversing the left motor and driving the right forward.
• stopMotors() — Stops both motors immediately.

Circuit Diagram

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How to Run

1. Assemble all components as per the wiring table.
2. Open the Arduino IDE and upload the provided code.
3. Place your robot on a track with a black line on a white surface.
4. Power the robot and watch it follow the line.
5. Adjust motor speeds if needed in Forward_Speed and Turn_Speed.

Demonstration

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Applications

• Entry-level robotics and automation
• Educational STEM learning kits
• Industrial line-following transport bots
• Maze-solving robots (with enhancements)

Future Improvements

➕ Add PID Control to reduce overshooting and create smoother navigation. ➕ Introduce EEPROM-based line calibration for better performance. ➕ Add a camera module and evolve toward vision-based line following.

Troubleshooting / Common Issues

• Robot not moving: Check motor wiring and power supply.
• Incorrect turns: Swap motor direction pins if needed.
• Sensors not detecting line: Ensure correct surface contrast and proper IR sensor height.
• Random behavior: Use Serial Monitor to debug sensor readings.

Credits / Acknowledgements

Developed by Awais Asghar as part of hands-on robotics projects.

License

This project is released under the MIT License. Feel free to use, modify, and share it with credit.