Robot That Follows Lines

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Project:

The arduino-based robot specifically designed to detect and trace lines on a surface. Using sensors, it can autonomously navigate by staying on its path. This technology is commonly used in automation and educational robotics projects..

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Parts and Materials:

 

Code:

 

int rightMotorA = 8;   // Right motor pin A
int rightMotorB = 9;   // Right motor pin B
int leftMotorA = 10;   // Left motor pin A
int leftMotorB = 11;   // Left motor pin B
int rightSensor = 6;   // Right side sensor pin
int leftSensor = 7;    // Left side sensor pin
int rightSensorVal = 0;
int leftSensorVal = 0;
int indicatorLED = 13;
int rightMotorSpeed = 3;  
int leftMotorSpeed = 5;

int baseSpeed = 200;    
int turnSpeed = 300;
int turnDelay = 10;

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void setup()
{
  pinMode(rightMotorA, OUTPUT);
  pinMode(rightMotorB, OUTPUT);
  pinMode(leftMotorA, OUTPUT);
  pinMode(leftMotorB, OUTPUT);
  pinMode(indicatorLED, OUTPUT);
  pinMode(rightSensor, INPUT);
  pinMode(leftSensor, INPUT);

  delay(5000);  // Initial delay after power up
}

void loop()
{
  rightSensorVal = digitalRead(rightSensor);
  leftSensorVal = digitalRead(leftSensor);

  if (leftSensorVal == LOW && rightSensorVal == LOW)
  {
    moveForward();
  }
  else if (leftSensorVal == HIGH && rightSensorVal == LOW)
  {
    turnLeft();
  }
  else if (leftSensorVal == LOW && rightSensorVal == HIGH)
  {
    turnRight();
  }
  else
  {
    halt();  // Stop robot if both sensors detect a line
  }
}

void moveForward()
{
  digitalWrite(rightMotorA, HIGH);
  digitalWrite(rightMotorB, LOW);
  digitalWrite(leftMotorA, HIGH);
  digitalWrite(leftMotorB, LOW);
  analogWrite(rightMotorSpeed, baseSpeed);
  analogWrite(leftMotorSpeed, baseSpeed);
}

void moveBackward()
{
  digitalWrite(rightMotorA, LOW);
  digitalWrite(rightMotorB, HIGH);
  digitalWrite(leftMotorA, LOW);
  digitalWrite(leftMotorB, HIGH);
  analogWrite(rightMotorSpeed, baseSpeed);
  analogWrite(leftMotorSpeed, baseSpeed);
}

void turnRight()
{
  digitalWrite(rightMotorA, LOW);
  digitalWrite(rightMotorB, HIGH);
  digitalWrite(leftMotorA, HIGH);
  digitalWrite(leftMotorB, LOW);
  analogWrite(rightMotorSpeed, turnSpeed);
  analogWrite(leftMotorSpeed, turnSpeed);
  delay(turnDelay);  // Short delay for turning
}

void turnLeft()
{
  digitalWrite(rightMotorA, HIGH);
  digitalWrite(rightMotorB, LOW);
  digitalWrite(leftMotorA, LOW);
  digitalWrite(leftMotorB, HIGH);
  analogWrite(rightMotorSpeed, turnSpeed);
  analogWrite(leftMotorSpeed, turnSpeed);
  delay(turnDelay);  // Short delay for turning
}

void halt()
{
  analogWrite(rightMotorSpeed, 0);
  analogWrite(leftMotorSpeed, 0);
}

​
 

Explanation:

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Variable Declaration & Initialization :
   - Motor and sensor pins on the microcontroller (like Arduino) are assigned:
     - `rightMotorA`, `rightMotorB`: Control pins for the right side motor.
     - `leftMotorA`, `leftMotorB`: Control pins for the left side motor.
     - `rightSensor`, `leftSensor`: Pins for sensors that detect lines on the right and left, respectively.
     - `indicatorLED`: Pin for a potential status LED.
     - `rightMotorSpeed`, `leftMotorSpeed`: Pins to control the speed of the right and left motors, respectively.
   - `baseSpeed` and `turnSpeed` represent motor speeds for normal forward movement and for turns. 
   - `turnDelay` represents a short delay when turning.

 

Setup Function (`setup`) :
   - Initializes the motor pins and sensor pins to be either OUTPUT (for the motors and LED) or INPUT (for the sensors).
   - Waits for 5 seconds after starting up. This is likely to give the user time to place the robot on the line before it starts following it.

 

Main Loop Function (`loop`):
   - Reads the values of the right and left sensors.
   - Depending on the sensor values, it decides which function to execute:
     - Both sensors `LOW` (not detecting line): `moveForward()`
     - Left sensor `HIGH` (detecting line) and right sensor `LOW`: `turnLeft()`
     - Left sensor `LOW` and right sensor `HIGH`: `turnRight()`
     - Both sensors `HIGH`: `halt()`

 

Movement Functions:
   - `moveForward()`: Makes the robot move straight ahead by driving both left and right motors in the forward direction at `baseSpeed`.
   - `moveBackward()`: Not used in the main loop, but it's designed to make the robot move backward. Both motors are driven in the reverse direction.
   - `turnRight()`: The robot turns right by moving the left motor forward and the right motor backward for a short duration defined by `turnDelay`.
   - `turnLeft()`: The robot turns left by moving the right motor forward and the left motor backward for a duration defined by `turnDelay`.
   - `halt()`: Stops both motors by setting their speed to zero.

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The logic behind the robot's movement is simple: if it's on the line, it corrects its path. If both sensors are on the line, it stops. If neither sensor is on the line, it proceeds forward. 

This code offers a basic line-following mechanism. In practical applications, further refinements might be required for smoother and more accurate line tracking.

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Circuit Design:

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