int Echo=A1,Trig=A0;
int Left_motor_back=8,Left_motor_go=9,Right_motor_go=10,Right_motor_back=11;
int key=7;
int beep=12;
int servopin=2;
int led3=3;
int led4=4;
//
int Front_Distance=0,Left_Distance=0,Right_Distance=0;
int myangle,pulsewidth,val;
//
void setup(){
  Serial.begin(9600);
  pinMode(key,INPUT);  pinMode(beep,OUTPUT);
  pinMode(Echo,INPUT); pinMode(Trig,OUTPUT);
  pinMode(servopin,OUTPUT);pinMode(led3,OUTPUT);pinMode(led4,OUTPUT);
  keysacn();
}
//
void run(){ //자동차가 달릴때 설정
  analogWrite(Right_motor_go,100); analogWrite(Right_motor_back,0);
  analogWrite(Left_motor_go ,100); analogWrite(Left_motor_back,0);
}
//
void brake(int time){ //자동차 멈출때 설정
  analogWrite(Right_motor_go,0); analogWrite(Right_motor_back,0);
  analogWrite(Left_motor_go ,0); analogWrite(Left_motor_back,0);
  delay(time*100);
}
//
void left(int time){ // 자동차 좌회전
  analogWrite(Right_motor_go,100); analogWrite(Right_motor_back,0);
  analogWrite(Left_motor_go ,  0); analogWrite(Left_motor_back,0);
  delay(time*100);
}
//
void spin_left(int time){ //자동차 스핀 왼쪽
  analogWrite(Right_motor_go,100); analogWrite(Right_motor_back,0);
  analogWrite(Left_motor_go ,  0); analogWrite(Left_motor_back,255);
  delay(time*100);
}
//
void right(int time){ //자동차 우회전
  analogWrite(Right_motor_go,  0); analogWrite(Right_motor_back,0);
  analogWrite(Left_motor_go ,100); analogWrite(Left_motor_back,0);
  delay(time*100);
}
//
void spin_right(int time){ //자동차 스핀 우회전
  analogWrite(Right_motor_go,  0); analogWrite(Right_motor_back,100);
  analogWrite(Left_motor_go ,100); analogWrite(Left_motor_back,0);
  delay(time*100);
}
//
void back(int time){ // 자동차 후진
  analogWrite(Right_motor_go,0); analogWrite(Right_motor_back,100);
  analogWrite(Left_motor_go ,0); analogWrite(Left_motor_back,100);
  delay(time*100);
}
//
void keysacn(){
  int val=digitalRead(key);
  while(!digitalRead(key))val=digitalRead(key); // 키를 누를 때까지 대기
  while(digitalRead(key)){                      // 키를 누르면, 뗄 때까지 대기
    delay(10); val=digitalRead(key);
    if(val==HIGH){ digitalWrite(beep,HIGH); } // 키를 누르면 부저 ON
    else         { digitalWrite(beep,LOW);  } // 키를 누르지 않으면 부저 OFF
  }
}
//
void klaxon (int time) {
    digitalWrite(beep,HIGH);
    delay(500);
    digitalWrite(beep,LOW);
}
void light_on (int time) {
  digitalWrite(led3,HIGH);
  digitalWrite(led4,HIGH);
}
void light_off (int time) {
  digitalWrite(led3,LOW);
  digitalWrite(led4,LOW);
}
void light_right (int time) {
  digitalWrite(led3,HIGH);
  digitalWrite(led4,LOW);
}
void light_left (int time) {
  digitalWrite(led3,LOW);
  digitalWrite(led4,HIGH);
}
float Distance_test(){ //거리 테스트
  digitalWrite(Trig,HIGH); delayMicroseconds(10); digitalWrite(Trig,LOW); //Trig
  float Fdistance=pulseIn(Echo,HIGH); Fdistance=Fdistance/58;             //Echo
  return Fdistance;
}
void servopulse(int servopin,int myangle){ //서브모터 설정
  pulsewidth=(myangle*10)+600;
  digitalWrite(servopin,HIGH); delayMicroseconds(pulsewidth); digitalWrite(servopin,LOW);  
  delay(20-pulsewidth/1000);
}
//
void front_detection(){ //앞쪽 장애물 감지
  for(int i=0; i<=5; i++)servopulse(servopin,90); //서보 90도
  Front_Distance=Distance_test();
}
//
void left_detection(){ //왼쪽 장애물 감지
  for(int i=0; i<=15; i++)servopulse(servopin,165); //서보 175도
  Left_Distance=Distance_test();
}
//
void right_detection(){
  for(int i=0; i<=15; i++)servopulse(servopin,15); //서보 15도
  Right_Distance=Distance_test();
}
//
void loop(){
   front_detection();
   light_on(10);
  if(Front_Distance<20){
    back(2); brake(2); 
    left_detection(); 
    right_detection(); 
    
    klaxon(2);
    //
    if    ((Left_Distance<20)&&(Right_Distance<20)){ spin_left(0.7);      }
    else if(Left_Distance>Right_Distance          ){light_right(10); left(5);  brake(1); }
    else                                           {light_left(10); right(5); brake(1); }
  }
  else{ run(); }
}
 
 
빨간부분이용해서 
저희가 하고 싶은 부분은 후진시 부저가 끊겨서 소리나는 것과 그리고 차가 좌회전할떄 좌측 led 켜짐 우측 led켜짐 입니다. 
delay를 이용하여 하기는 했는데 좀 더 편리한 방법이 있을꺼 같아서 질문드립니다!!