Program the Line Follower Bot

Step 1

What does it do?

The Line Follower Bot uses while loops to control its motors while it takes IR sensor input so that it follows black lines on a white surface. You’ll be able to put this robot on a line drawn with a black electric tape and have it follow the line around.

This is the Line Follower Bot’s pseudocode:

While pin 13 sees black, turn left.
While pin 16 sees black, turn right.

Here’s the view of the bottom of the Smart Inventor Board’s bottom side with the pins labeled. This is the side that will be facing the ground.

Line Follower Smart Inventor Board Bottom View

Step 2

Code setup

The first thing you need to do is include the Smart Inventor library at the top of your code. Next, in void setup(), set up your motors, and then set pins 13 and 16 as inputs. These are the two bottom IR sensors right next to the middle IR sensor.

#include <SmartInventor.h>    //including the library!
 
void setup() {
  SmartInventor.DCMotorUse(); //set up your motors
  
  //set pins 13 and 16
  pinMode(13, INPUT);
  pinMode(16, INPUT);
}

Step 3

Turning Right

Include the code below in void loop() so that when the right sensor, pin 16, detects a black line, the left motor rotates counter clockwise and the right motor stops. This will turn your robot to the right.

void loop() {
  while(digitalRead(16) == 0)            //while pin 16 sees a black
  {
    SmartInventor.DCMotor(M1, CCW, 50);  //rotate the left motor
    SmartInventor.DCMotor(M2, STOP, 0);  //stop the right motor
  }
}

Step 4

Turning Left

Do the same thing for the right motor so that when the left sensor, pin 13, detects a black line, the right motor rotates clockwise and the left motor stops. This will turn your robot to the left.

#include <SmartInventor.h>
 
void setup() {
  SmartInventor.DCMotorUse();
 
  pinMode(13, INPUT);
  pinMode(16, INPUT);
}
 
void loop() {
  while(digitalRead(16) == 0)
  {
    SmartInventor.DCMotor(M1, CCW, 50);
    SmartInventor.DCMotor(M2, STOP, 0);
  }
 
  while(digitalRead(13) == 0)                //while pin 13 sees a black line
  {
    SmartInventor.DCMotor(M1, STOP, 0);      //stop the left motor
    SmartInventor.DCMotor(M2, CW, 50);       //rotate the right motor
  }
}

Step 5

How does it move?

So what’s happening here? When the Smart Inventor Board is facing downward with pin 16 (on the right) and pin 13 (on the left) facing the ground. Like we said in the first step, the code is telling your robot:

While the right sensor sees black, turn right by rotating the left motor.
While the left sensor sees black, turn left by rotating the right motor.

This means that your bot just keeps wiggling back and forth, making little left turns and right turns a bunch of times every time it detects a line. Each time your bot makes one of these turns it moves forward a little bit so it keeps moving along the line.

Tips!

You can adjust the sensitivity of the IR sensors by using a screwdriver to turn the potentiometer, which is the white dial next to the DIP switch. As you adjust it to be more sensitive, the IR sensor will be able to distinguish between white and black better.

Optional: try customizing your bot’s movement a little bit! Play around with motor speed or the delay time in your code to see what happens.

Step 6

Final code

Your final code should look like the one below:

#include <SmartInventor.h> 

void setup() {  
    SmartInventor.DCMotorUse();   

    pinMode(13, INPUT);  
    pinMode(16, INPUT);
} 

void loop() {  
    while(digitalRead(16) == 0) //while pin 16 sees a black line  
    {    
        SmartInventor.DCMotor(M1, CCW, 50); //rotate the right motor    
        SmartInventor.DCMotor(M2, STOP, 0); //stop the left motor  
    }   

    while(digitalRead(13) == 0) //while pin 13 sees a black line  
    {    
        SmartInventor.DCMotor(M1, STOP, 0); //stop the right motor    
        SmartInventor.DCMotor(M2, CW, 50);  //rotate the left motor  
    }
}

Step 7

Video

Not sure about the lesson or want to check your program? Watch the video!

This lesson uses:

Grade level:

Approx. time required:

CSTA

CCSS