#include <Ultrasonic.h>

#include <Servo.h>

Servo servo1;

int trigPin = 9;

int echoPin = 8;

long distance;

long duration;

void setup() 

{

servo1.attach(7); 

 pinMode(trigPin, OUTPUT);

 pinMode(echoPin, INPUT);// put your setup code here, to run once:

}

void loop()

{

  ultra_sonic();

  servo1.write(90);

  if(distance <=100)

  {

  servo1.write(100);

  }

}

void ultra_sonic()

{

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  distance = duration*0.034/2;

  }