Line Follower Robot

Line follower robot is a robot that is often contested because it is quite simple for the beginner like me. This robot uses Infra red sensor to detect or recognize the line. The sensor consists of two pieces of infrared LEDs, a single transceiver and the other one as receiver. Working principle is

IR LED emits infrared radiation. This radiation illuminates the surface in front of LED. Surface reflects the infrared light. Depending on reflectivity of the surface, amount of light reflected varies. This reflected light is made incident on reverse biased IR sensor. When photons are incident on reverse biased junction of this diode, electron-hole pairs are generated, which results in reverse leakage current. Amount of electron-hole pairs generated depends on intensity of incident IR radiation. More intense radiation results in more reverse leakage current. This current can be passed through a resistor so as to get proportional voltage. Thus as intensity of incident rays varies, voltage across resistor will vary accordingly.

This voltage can then be given to OPAMP based comparator.Output of the comparator can be read by uC. Alternatively, you can use on-chip ADC in AVR microcontroller to measure this voltage and perform comparison in software.

 ( sumber: IR sensor)

Line follower robot that I made consisting of two pairs of infrared sensors. the way it works is if the right sensor over the line then the robot will move left, if left out of the line sensor, the robot will move to right.
Here's video line follower robot that I made

  


and this program

void setup() {  
  pinMode(2,OUTPUT);  // kendali motor 1
  pinMode(3,OUTPUT);  // motor 1 +
  pinMode(4,OUTPUT);  // motor 1 -
  pinMode(5,OUTPUT);  // kendali motor 2
  pinMode(6,OUTPUT);  // motor 2 +
  pinMode(7,OUTPUT);  // motor 2 -
  //pinMode(13,OUTPUT); // Buzzer
  Serial.begin(9600);
}
void kanan(void){
  digitalWrite(2,LOW);
  digitalWrite(5,LOW);     
  delayMicroseconds(100);
  digitalWrite(3,HIGH);
  digitalWrite(4,LOW);     
  delayMicroseconds(100);
  digitalWrite(6,LOW);
  digitalWrite(7,HIGH);     
  delayMicroseconds(100);
  digitalWrite(2,HIGH);
  digitalWrite(5,HIGH);     
  delayMicroseconds(200);  
}

void kiri(void){
  digitalWrite(2,LOW);
  digitalWrite(5,LOW);     
  delayMicroseconds(100);
  digitalWrite(3,LOW);
  digitalWrite(4,HIGH);     
  delayMicroseconds(100);
  digitalWrite(6,HIGH);
  digitalWrite(7,LOW);     
  delayMicroseconds(100);
  digitalWrite(2,HIGH);
  digitalWrite(5,HIGH);     
  delayMicroseconds(200);
}
void maju(void){
  digitalWrite(2,LOW);
  digitalWrite(5,LOW);     
  delayMicroseconds(100);
  digitalWrite(3,LOW);
  digitalWrite(4,HIGH);     
  delayMicroseconds(100);
  digitalWrite(6,LOW);
  digitalWrite(7,HIGH);     
  delayMicroseconds(100);
  digitalWrite(2,HIGH);
  digitalWrite(5,HIGH);     
  delayMicroseconds(200);
}
void henti(void){
  digitalWrite(2,LOW);
  digitalWrite(5,LOW);     
  delayMicroseconds(100);
  digitalWrite(3,LOW);
  digitalWrite(4,LOW);     
  delayMicroseconds(100);
  digitalWrite(6,LOW);
  digitalWrite(7,LOW);     
  delayMicroseconds(100);
  digitalWrite(2,LOW);
  digitalWrite(5,LOW);     
  delayMicroseconds(200);
}
 

void loop() {
  int sensor,sensor2;
  // baca nilai sensor di PIN A0 (Analog) dan kirim ke serial
  sensor=analogRead(A0);//kanan
  sensor2=analogRead(A1); //kiri
  Serial.println(sensor);
  
if(sensor>=900&&sensor2>=900) {
  maju();
//digitalWrite(13,LOW);
}
if (sensor<900){
kiri();
}
if(sensor2<900){
  kanan();
}
if(sensor<900 && sensor2<900){
  henti();
  delay(200);
  kanan();
  if(sensor >= 900 || sensor2 >= 900) {
    maju();
  }
  delay(500);
}
}