07. Robotics with Arduino

🔍 How IR Sensors Work

• IR sensors emit invisible light and detect how much is reflected back.
• White surfaces reflect IR light, while black surfaces absorb it.
• This lets the sensor detect if it’s over a white or black area.

🎯 Application in Line Following

Robots can use multiple IR sensors (usually 2 or 3) to detect their position relative to a black line on a white background:

• If the center sensor is on the line, go straight.
• If the left sensor sees the line, turn left.
• If the right sensor sees the line, turn right.

🧰 Components Needed

• 1 x Arduino Uno
• 2 or 3 x IR sensors (like TCRT5000 modules)
• Jumper wires
• Small black electrical tape for the line

📐 Wiring the Sensors

• Connect VCC of each IR sensor to 5V on Arduino.
• Connect GND to GND.
• Connect OUT pins to Arduino digital pins (e.g., D2, D3, D4).

💻 Sample Code to Read Sensor Values

int leftSensor = 2;
int centerSensor = 3;
int rightSensor = 4;

void setup() {
  pinMode(leftSensor, INPUT);
  pinMode(centerSensor, INPUT);
  pinMode(rightSensor, INPUT);
  Serial.begin(9600);
}

void loop() {
  int left = digitalRead(leftSensor);
  int center = digitalRead(centerSensor);
  int right = digitalRead(rightSensor);

  Serial.print("Left: ");
  Serial.print(left);
  Serial.print("  Center: ");
  Serial.print(center);
  Serial.print("  Right: ");
  Serial.println(right);

  delay(200);
}

📘 How to Test

• Upload the code and open the Serial Monitor.
• Move the sensor over the black line and white background.
• You should see changes in the printed values (0 or 1).

🔧 Logic Output