Building Your First Autonomous Line Follower

Line following is the "Hello World" of mobile robotics. In this guide, we'll build a PID-controlled robot using an Arduino and a generic IR array.

Introduction

Precision navigation is critical in industrial AGVs. A simple bang-bang controller causes oscillation. To fix this, we use PID (Proportional-Integral-Derivative) control.

Hardware Required

• Arduino Uno or Nano
• L298N Motor Driver
• 5-Channel IR Sensor Array (TCRT5000)
• 2x DC Gear Motors + Chassis

The Code

Here is a snippet of the PID calculation in C++:

// PID Constants
float Kp = 12.0; 
float Kd = 8.5;
float Ki = 0.05;

void loop() {
    int error = readSensors();
    
    // Proportional
    int P = error;
    
    // Integral
    static int I = 0;
    I = I + error;
    
    // Derivative
    static int lastError = 0;
    int D = error - lastError;
    lastError = error;
    
    // Total Correction
    int correction = (Kp * P) + (Ki * I) + (Kd * D);
    
    motorControl(baseSpeed + correction, baseSpeed - correction);
}
                

Conclusion

By tuning Kp, Ki, and Kd, your robot will follow the line smoothly even at high speeds. Stay tuned for our next article on Obstacle Avoidance using Ultrasonics.

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