Object following robot

object_follower.ino

#include <Servo.h>

#define udm_trig 7
#define udm_echo 6
#define RightMotorPin1 2
#define RightMotorPin2 3
#define LeftMotorPin1 4
#define LeftMotorPin2 5
#define soundpin 12
Servo sensor_servo;

int angle,follow_object_flag=0;
long duration, object_distance;
void setup()
{
  sensor_servo.attach(10);  
  pinMode(udm_trig,OUTPUT);
  pinMode(udm_echo,INPUT);
  pinMode(2,OUTPUT);
  pinMode(3,OUTPUT);
  pinMode(4,OUTPUT);
  pinMode(5,OUTPUT);
  pinMode(12,OUTPUT);
  digitalWrite(2,LOW);
  digitalWrite(3,LOW);
  digitalWrite(4,LOW);
  digitalWrite(5,LOW);
  digitalWrite(12,LOW);
  sensor_servo.write(90);
  delay(2000);
}

void turn_left()
  {
    digitalWrite(RightMotorPin1, HIGH);
    digitalWrite(RightMotorPin2, LOW);
    delay(2000);
    digitalWrite(RightMotorPin1, LOW);
  }
void turn_right()
  {
    digitalWrite(LeftMotorPin1, HIGH);
    digitalWrite(LeftMotorPin2, LOW);
    delay(2000);
    digitalWrite(LeftMotorPin1, LOW);
  }
void move_forward()
  {
    digitalWrite(RightMotorPin1, HIGH);
    digitalWrite(RightMotorPin2, LOW);
    digitalWrite(LeftMotorPin1, HIGH);
    digitalWrite(LeftMotorPin2, LOW);   
  }
void stop_robot()
  {
    digitalWrite(RightMotorPin1, LOW);
    digitalWrite(RightMotorPin2, LOW);
    digitalWrite(LeftMotorPin1, LOW);
    digitalWrite(LeftMotorPin2, LOW); 
  }
void follow_object()
  {
      digitalWrite(udm_trig,HIGH);
      delayMicroseconds(10);
      digitalWrite(udm_trig,HIGH);
      duration = pulseIn(udm_echo, HIGH);
      object_distance = duration/29/2;
      if(object_distance>30) follow_object_flag=1; 
  }  
void loop() 
 {
  for(angle=45;angle<135;angle+=5)
    {
      sensor_servo.write(angle);
      digitalWrite(udm_trig,HIGH);
      delayMicroseconds(10);
      digitalWrite(udm_trig,HIGH);
      duration = pulseIn(udm_echo, HIGH);
      object_distance = duration/29/2;
      if(object_distance<30) 
        {
          sensor_servo.write(90);
          if(angle<90) turn_left();
          else if(angle>90) turn_right();
          digitalWrite(soundpin,HIGH);
          move_forward();
          while(follow_object_flag==0)
            {
              follow_object();
              delay(200);  
            }
           stop_robot();
           digitalWrite(soundpin,LOW);
           follow_object_flag=0;
        }
      delay(100);  
    }
  for(angle=135;angle>35;angle-=5)
    {
      sensor_servo.write(angle);
      delay(20);
    }  
}