#include <Servo.h>

Servo myservo;   

int pos = 0;

int cm = 0;

long readUltrasonicDistance(int triggerPin, int echoPin)
{
  pinMode(triggerPin, OUTPUT); 
    digitalWrite(triggerPin, LOW);
      delayMicroseconds(2);
        digitalWrite(triggerPin, HIGH);
          delayMicroseconds(10);
            digitalWrite(triggerPin, LOW);
              pinMode(echoPin, INPUT);
                return pulseIn(echoPin, HIGH);
                }



                void setup() {
                  digitalWrite(12,LOW);
                    myservo.attach(9); 
                      Serial.begin(9600);
                      }

                      void loop() {
                         cm = 0.01723 * readUltrasonicDistance(6, 7);

                           if(cm<30){
                             Serial.print(cm);
                               Serial.println("cm");
                                 
                                  for (pos = 0; pos <= 120; pos += 1) { 
                                      myservo.write(pos);             
                                         delay(15);                       
                                           }
                                             delay(500);

                                               for (pos = 120; pos >= 0; pos -= 1) { 
                                                   myservo.write(pos);
                                                       delay(15);                                     
                                                         }
                                                           delay(5000); //add delay how much you want
                                                             }                          
                                                             }