Riki

int setDistance = 0;

int distance;

#include <NewPing.h>
#include <MedianFilter.h>
#include <Wire.h>
#include <MedianFilter.h>

#define TRIGGER_PIN  12  // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN     11 // Arduino pin tied to echo pin on the ultrasonic sensor.
#define MAX_DISTANCE 450 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.


const int relayPin = 4;
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.

MedianFilter filter(31, 0);

void setup()
{
  Serial.begin(115200); // Open serial monitor at 115200 baud to see ping results.
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, LOW);
}

void loop() {


  unsigned int o, uS = sonar.ping(); // Send ping, get ping time in microseconds (uS).

  filter.in(uS);
  o = filter.out();
  Serial.println("Ping: ");

  distance =  o / US_ROUNDTRIP_CM;

  Serial.println(distance);

  if(distance <= 105)
  {
    digitalWrite(relayPin, HIGH);
  }
  else
  {
    digitalWrite(relayPin, LOW);
  }
}