🤖 Line Following Robot

An autonomous Arduino-based robot that follows a black line on a white surface using IR sensors and visual feedback via LCD display and LEDs.

📋 Table of Contents

• Overview
• Features
• Hardware Requirements
• Circuit Diagram
• Software Requirements
• Installation
• Usage
• How It Works
• Configuration
• Troubleshooting
• Contributing
• License
• Acknowledgments

🎯 Overview

This project is an autonomous line-following robot designed as a college mini-project for the E&TC branch. The robot uses infrared (IR) sensors to detect and follow a black line on a white surface, making it perfect for understanding robotics, sensor integration, and control systems.

Key Highlights:

• Real-time LCD feedback showing robot state
• Visual LED indicators for direction
• Smooth motor control with adjustable speeds
• Simple yet effective line-following algorithm

✨ Features

• Autonomous Navigation: Follows black lines without human intervention
• Real-time Display: 16x2 LCD shows current robot status
• Visual Indicators: 5 LEDs provide additional status feedback
• Dual IR Sensors: Left and right sensors for accurate line detection
• Motor Control: PWM-based speed control for smooth movements
• Multiple States: Forward, Left Turn, Right Turn, and Stop
• Compact Design: Optimized for small to medium-sized tracks

🔧 Hardware Requirements

Essential Components

Component	Specification	Quantity	Purpose
Microcontroller	Arduino Mega (or Uno)	1	Main control board
Motor Driver	L293D IC	1	Controls DC motors
IR Sensors	Digital IR sensor modules	2	Line detection
DC Motors	3-12V DC geared motors	2	Robot movement
LCD Display	16x2 I2C LCD	1	Status display
LEDs	5mm LEDs (any color)	5	Visual indicators
Battery	7.4V Li-ion or 9V battery	1	Power source
Chassis	Robot chassis kit	1	Physical structure
Wheels	Compatible with motors	2	Movement
Castor Wheel	Small ball caster	1	Support
Resistors	220Ω resistors	5	LED current limiting
Jumper Wires	Male-to-Male, Male-to-Female	-	Connections

Optional Components

• Breadboard for prototyping
• Switch for power control
• Additional LEDs for decoration

📐 Circuit Diagram

Pin Configuration

Motor Driver (L293D) Connections

Arduino Pin  →  L293D Pin    →  Function
    5        →  Enable A     →  Right motor speed (PWM)
    6        →  Input 1      →  Right motor direction
    7        →  Input 2      →  Right motor direction
    8        →  Enable B     →  Left motor speed (PWM)
    9        →  Input 3      →  Left motor direction
    10       →  Input 4      →  Left motor direction

Sensor Connections

Arduino Pin  →  Component
    2        →  Left IR Sensor (Digital Output)
    4        →  Right IR Sensor (Digital Output)

Display and LED Connections

Arduino Pin  →  Component
   SDA       →  LCD SDA (I2C Data)
   SCL       →  LCD SCL (I2C Clock)
   A0        →  LED 1 (via 220Ω resistor)
   A1        →  LED 2 (via 220Ω resistor)
   A2        →  LED 3 (via 220Ω resistor)
   A3        →  LED 4 (via 220Ω resistor)
   A4        →  LED 5 (via 220Ω resistor)

Wiring Diagram

                    Arduino Mega
                   ┌─────────────┐
    Left Sensor ───┤ 2           │
    Right Sensor ──┤ 4           │
                   │             │
    Motor Driver ──┤ 5,6,7,8,9,10│
                   │             │
    LCD (I2C) ─────┤ SDA, SCL    │
    LEDs ──────────┤ A0-A4       │
                   └─────────────┘

Note: Detailed circuit diagrams can be found in the /docs folder.

💻 Software Requirements

• Arduino IDE (v1.8.x or higher) - Download here
• Required Libraries:
  • Wire.h (built-in with Arduino IDE)
  • LiquidCrystal_I2C.h - Installation guide

Installing Libraries

1. Open Arduino IDE
2. Go to Sketch → Include Library → Manage Libraries
3. Search for "LiquidCrystal I2C"
4. Install the library by Frank de Brabander

Alternative method (Manual Installation):

# Navigate to Arduino libraries folder
cd ~/Documents/Arduino/libraries

# Download the library
git clone https://github.com/johnrickman/LiquidCrystal_I2C.git

🚀 Installation

Step 1: Clone the Repository

git clone https://github.com/kulkarnishub377/A_line_following_robot.git
cd A_line_following_robot

Step 2: Open the Project

1. Launch Arduino IDE
2. Open src/line_following_robot.ino
3. Select your Arduino board: Tools → Board → Arduino Mega (or your board)
4. Select the correct port: Tools → Port → (your Arduino port)

Step 3: Upload the Code

1. Click the Upload button (→) or press Ctrl+U
2. Wait for the upload to complete
3. You should see "Done uploading" message

📖 Usage

Initial Setup

1. Power On: Connect the battery to the Arduino
2. LCD Display: Should show "LINE FOLLOWING ROBOT" on startup
3. LED Indicators: Three status LEDs (3, 4, 5) will light up
4. Calibration: Place the robot on a test track

Operating the Robot

1. Prepare the Track:

   • Use a white surface with a black line (2-3 cm wide)
   • Ensure good contrast between line and surface
   • Start with simple curves before complex paths

2. Position the Robot:

   • Place robot so the line is between both sensors
   • Ensure sensors are 1-2 cm above the surface

3. Power On and Go:

   • The robot will automatically start following the line
   • Watch the LCD for status updates
   • LED indicators show turning direction

Understanding Robot States

LCD Display	LED Status	Robot Action
"Moving Forward"	LED 1 & 2 OFF	Going straight on the line
"Turning Right"	LED 1 ON, LED 2 OFF	Turning right to follow line
"Turning Left"	LED 1 OFF, LED 2 ON	Turning left to follow line
"Stopped"	LED 1 & 2 OFF	Both sensors on black (end of line)

⚙️ How It Works

Algorithm Overview

The robot uses a simple but effective line-following algorithm:

┌─────────────────────────────────────────┐
│  Read IR Sensor Values                  │
│  (0 = White surface, 1 = Black line)    │
└────────────────┬────────────────────────┘
                 │
        ┌────────┴────────┐
        │  Sensor Logic   │
        └────────┬────────┘
                 │
     ┌───────────┴───────────┐
     │                       │
   Both       Left=1      Right=1     Both=1
  Sensors=0   Right=0     Left=0      (Stop)
     │           │           │           │
  Forward    Turn Right  Turn Left     Stop

Code Logic Explained

1. Sensor Reading:

   • Continuously reads left and right IR sensors
   • 0 = sensor over white surface
   • 1 = sensor over black line

2. Decision Making:

   if (Left=0 && Right=0)  → Both on white → Move Forward
   if (Left=0 && Right=1)  → Right on line → Turn Right
   if (Left=1 && Right=0)  → Left on line  → Turn Left
   if (Left=1 && Right=1)  → Both on line  → Stop

3. Motor Control:

   • Forward: Both motors at 150 PWM (speed)
   • Turning: Motors at 100 PWM with opposite directions
   • Stop: Both motors at 0 PWM

4. Feedback:

   • LCD updates with current state
   • LEDs indicate turning direction
   • Status LEDs remain lit during operation

🔧 Configuration

Adjusting Motor Speed

In the code, you can modify these values for different speeds:

// In forward() function
analogWrite(enA, 150); // Right Motor Speed (0-255)
analogWrite(enB, 150); // Left Motor Speed (0-255)

// In turnRight() and turnLeft() functions
analogWrite(enA, 100); // Turning Speed (0-255)
analogWrite(enB, 100);

Speed Guidelines:

• Lower values (80-120): Better control, slower movement
• Medium values (120-180): Balanced speed and control
• Higher values (180-255): Faster but less stable

Sensor Sensitivity

• Adjust sensor height: 1-2 cm above surface is optimal
• Use sensor potentiometer to adjust detection threshold
• Test on your specific track surface

LCD I2C Address

If your LCD doesn't work, try changing the address:

LiquidCrystal_I2C lcd(0x27, 16, 2); // Try 0x3F if 0x27 doesn't work

To find your LCD address, use an I2C scanner sketch.

🐛 Troubleshooting

Common Issues and Solutions

Robot Doesn't Move

• Check: Battery voltage (should be 7-12V)
• Check: Motor driver connections
• Check: Enable pins are receiving PWM signals
• Solution: Verify all connections match the pin configuration

LCD Shows Nothing

• Check: I2C address (try 0x3F instead of 0x27)
• Check: I2C connections (SDA and SCL)
• Check: Contrast potentiometer on LCD
• Solution: Run I2C scanner to find correct address

Robot Doesn't Follow Line

• Check: Sensor height (1-2 cm optimal)
• Check: Line contrast (black on white)
• Check: Sensor orientation (pointing downward)
• Solution: Calibrate sensors using potentiometer

Erratic Movement

• Check: Loose connections
• Check: Insufficient power supply
• Check: Motor speed values (might be too high)
• Solution: Lower motor speeds, secure all connections

One Motor Not Working

• Check: Motor driver connections for that motor
• Check: Motor itself (swap motors to test)
• Check: Enable pin PWM signal
• Solution: Replace faulty motor or check driver IC

Debug Mode

Add serial debugging to troubleshoot:

void setup() {
  Serial.begin(9600);
  // ... rest of setup
}

void loop() {
  Serial.print("Left: ");
  Serial.print(digitalRead(L_S));
  Serial.print(" Right: ");
  Serial.println(digitalRead(R_S));
  // ... rest of loop
}

🤝 Contributing

We welcome contributions! Please see our Contributing Guidelines for details.

Ways to Contribute

• 🐛 Report bugs
• 💡 Suggest new features
• 📝 Improve documentation
• 🔧 Submit code improvements
• 🎨 Add circuit diagrams or images

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

Team Members

This project was developed as a collaborative effort by E&TC students. Special thanks to all team members who contributed their time, skills, and dedication.

Learning Outcomes

• ✅ Sensor integration and calibration
• ✅ Motor control systems
• ✅ Embedded programming with Arduino
• ✅ Control algorithms and logic
• ✅ Hardware-software integration
• ✅ Team collaboration and project management

Resources

• Arduino Community Forums
• L293D Motor Driver Documentation
• IR Sensor Tutorials
• Robotics Community

Inspiration

This project showcases the practical application of robotics and automation in real-world scenarios, making it perfect for:

• Educational purposes
• STEM demonstrations
• Robotics competitions
• Learning embedded systems

📞 Support

If you have questions or need help:

• Open an Issue
• Check the Troubleshooting section
• Review existing issues for solutions

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Made with ❤️ by robotics enthusiasts

#Robotics #Arduino #Engineering #STEM #IoT #Automation