Obstacle detector using Ultrasonic sensor and Arduino:

Obstacle detector using Ultrasonic sensor and Arduino: 

int Echo1 = A4; //LEFT_SENSOR ECHO
int Trig1 = A5; //LEFT_SENSOR TRIG
int Echo2 = A2; //MID_SENSOR ECHO
int Trig2 = A3; //MID_SENSOR TRIG
int Echo3 = A0; //RIGHT_SENSOR ECHO
int Trig3 = A1; //RIGHT_SENSOR TRIG

int in1 = 8;
int in2 = 9;
int in3 = 6;
int in4 = 7;
int ENA = 5;
int ENB = 11;
int ABS = 200;
int Left_Distance = 0,Right_Distance = 0,Middle_Distance = 0 ;
void _mForward()
{

digitalWrite(in1,LOW);
digitalWrite(in2,HIGH);
digitalWrite(in3,LOW);
digitalWrite(in4,HIGH);
analogWrite(ENA,ABS);
 analogWrite(ENB,ABS);
Serial.println("ROBOT_MOVING_FORWARD");
}
void _mBack()
{

digitalWrite(in1,HIGH);
digitalWrite(in2,LOW);
digitalWrite(in3,HIGH);
digitalWrite(in4,LOW);
analogWrite(ENA,ABS);
 analogWrite(ENB,ABS);
Serial.println("ROBOT_MOVING_BACKWARD");
}
void _mleft()
{

digitalWrite(in1,LOW);
digitalWrite(in2,HIGH);
digitalWrite(in3,LOW);
digitalWrite(in4,LOW);
analogWrite(ENA,ABS);
 analogWrite(ENB,ABS);
Serial.println("ROBOT_MOVING_LEFT");
}
void _mright()
{

digitalWrite(in1,LOW);
digitalWrite(in2,LOW);
digitalWrite(in3,LOW);
digitalWrite(in4,HIGH);
analogWrite(ENA,ABS);
 analogWrite(ENB,ABS);
Serial.println("ROBOT_MOVING_RIGHT");
}
void _mStop()
{
digitalWrite(in1,LOW);
digitalWrite(in2,LOW);
digitalWrite(in3,LOW);
digitalWrite(in4,LOW);
 digitalWrite(ENA,LOW);
  digitalWrite(ENB,LOW);
Serial.println("ROBOT_STOP");
}

int Left_Distance_test()
{
digitalWrite(Trig1, LOW);
delayMicroseconds(2);
digitalWrite(Trig1, HIGH);
delayMicroseconds(20);
digitalWrite(Trig1, LOW);
float Fdistance = pulseIn(Echo1, HIGH);
delay(10);

Fdistance= Fdistance/ 29 / 2;
return (int)Fdistance;
}
int Middle_Distance_test()
{
digitalWrite(Trig2, LOW);
delayMicroseconds(2);
digitalWrite(Trig2, HIGH);
delayMicroseconds(20);
digitalWrite(Trig2, LOW);
float Fdistance = pulseIn(Echo2, HIGH);
delay(10);
Fdistance= Fdistance/ 29 / 2;
return (int)Fdistance;
}
int Right_Distance_test()
{
digitalWrite(Trig3, LOW);
delayMicroseconds(2);
digitalWrite(Trig3, HIGH);
delayMicroseconds(20);
digitalWrite(Trig3, LOW);
float Fdistance = pulseIn(Echo3, HIGH);
delay(10);
Fdistance= Fdistance/ 29 / 2;
return (int)Fdistance;
}
void setup()
{
Serial.begin(9600);
pinMode(Echo1, INPUT);
pinMode(Trig1, OUTPUT);
pinMode(Echo2, INPUT);
pinMode(Trig2, OUTPUT);
pinMode(Echo3, INPUT);
pinMode(Trig3, OUTPUT);
pinMode(in1,OUTPUT);
pinMode(in2,OUTPUT);
pinMode(in3,OUTPUT);
pinMode(in4,OUTPUT);
 pinMode(ENA,OUTPUT);
  pinMode(ENB,OUTPUT);

_mStop();
}
void loop()
{
Left_Distance = Left_Distance_test();
delay(10);
Middle_Distance = Middle_Distance_test();
delay(10);
Right_Distance = Right_Distance_test();
delay(10);
Serial.println("Left_Distance\tMiddle_Distance\tRight_Distance\tStatus\n");
Serial.print(Left_Distance);
Serial.print("cm\t\t");
Serial.print(Middle_Distance);
Serial.print("cm\t\t");
Serial.print(Right_Distance);
Serial.print("cm\t\t");
 if(Middle_Distance<=50)
    {  

               
      if(Right_Distance>Left_Distance)
      {
        if((Right_Distance<=30)&&(Left_Distance<=30))
       {_mStop();
      delay(200);
        _mBack();
        delay(1000);
     
       }
      else{
     
   
        _mright();
        delay(500);}
     
      }
       else if(Right_Distance<Left_Distance)
       {
        if((Right_Distance<=30)&&(Left_Distance<=30))
     
       {_mStop();
      delay(200);
        _mBack();
        delay(1000);
       }
       else{
 
        _mleft();
        delay(500);
       }
    }
    }
    else if(Right_Distance<=15)
    {
      _mleft();
      delay(500);
    }
 
    else if(Left_Distance<=15)
    {
      _mright();
      delay(500);
    }
    else{
        _mForward();
        }
     
}

Circuit Diagram: