Self guided robot with IR sensors

An autonomous robot designed to follow a predefined path using infrared sensors, ideal for logistics and automation.

IntermediateProtip3 days139

Things used in this project

Hardware components

Arduino Nano R3

Rechargeable Battery, Lithium Ion

Rocker Switch, Non Illuminated

SparkFun Dual H-Bridge motor drivers L298

DC Motor, 12 V

We used 8V power for driver in motors

Jumper wires (generic)

Digilent IR Range Sensor

Machine Screw, M3

Software apps and online services

Arduino IDE

Story

In this project, we designed a line follower robot that uses five infrared (IR) sensors to detect and follow a black line on a white surface. These sensors send information about the line’s position to an Arduino Nano board.

We programmed the robot so that if the left sensors detect the line, the robot turns left; if the right sensors detect the line, the robot turns right. When only the middle sensor is active, the robot moves straight. (Even if none of the sensors detect the line, the robot still moves forward — this is due to the limited number of sensors.)

The motors are controlled by an L298N driver, and their speed can be adjusted using PWM pins.

For power, we used two 3.7V lithium batteries, and the required 5V for the Arduino and sensors is provided through the driver.

Our robot has two wheels connected to motors, and a third wheel is a free-rotating caster wheel.

Robot code

const int sensorPins[5] = {2, 3, 4, 5, 6};
 

const int IN1 = 7;   
const int IN2 = 8;  
const int IN3 = 12; 
const int IN4 = 13; 
const int ENA = 9;   
const int ENB = 10;  
 

int motorSpeedF = 150;
int motorSpeedB = 120;
void setup() { 
  for (int i = 0; i < 5; i++) { 
    pinMode(sensorPins[i], INPUT); 
  } 
  pinMode(IN1, OUTPUT); 
  pinMode(IN2, OUTPUT); 
  pinMode(IN3, OUTPUT); 
  pinMode(IN4, OUTPUT); 
  pinMode(ENA, OUTPUT); 
  pinMode(ENB, OUTPUT); 
} 
 
void loop() { 
  
  bool sensors[5]; 
  for (int i = 0; i < 5; i++) { 
    sensors[i] = digitalRead(sensorPins[i]); 
  } 
  if (!sensors[0] || !sensors[1]) {       
    turnLeft();                         
  }  
  else if (!sensors[3] || !sensors[4]) { 
    turnRight();                         
  }  
  else if (!sensors[2]) {                 
    moveForward();                       
  }                           
} 
  
void moveForward() { 
  digitalWrite(IN1, HIGH); 
  digitalWrite(IN2, LOW); 
  analogWrite(ENA, motorSpeedF); 
 
  digitalWrite(IN3, HIGH); 
  digitalWrite(IN4, LOW); 
  analogWrite(ENB, motorSpeedF);  
} 
 
void turnLeft() { 
  digitalWrite(IN1, LOW); 
  digitalWrite(IN2, HIGH); 
  analogWrite(ENA, motorSpeedB); 
 
  digitalWrite(IN3, HIGH); 
  digitalWrite(IN4, LOW); 
  analogWrite(ENB, motorSpeedF); 
} 
 
void turnRight() { 
  digitalWrite(IN1, HIGH); 
  digitalWrite(IN2, LOW); 
  analogWrite(ENA, motorSpeedF); 
 
  digitalWrite(IN3, LOW); 
  digitalWrite(IN4, HIGH); 
  analogWrite(ENB, motorSpeedB);
}