Filtering out bad readings from ultrasonic sensors

Other Hardware Sensors
1

i am making a project on my arduino uno. it is a ultrasonic sensor and when it gets a read below 80 it sets off two LEDS i hoped to have this project done by halloween because i wanted to have a pumpkin with this in it so when people come by the lights on the inside turn on it is a simple project but there is a problem. the sensor i have (HC-SRO4) gives off bad reads ever ounces in a while and this cause the LEDS to flash off or on at random times. is there a way to filter out these reads i will put my code below and an example of a read i would like it to filter out.

My code:
const int trig = 12;
const int echo = 13;

const int LED1 = 8;
const int LED6 = 3;
const int LED7 = 2;

int duration = 0;
int distance = 0;

void setup()
{
pinMode(trig , OUTPUT);
pinMode(echo , INPUT);

pinMode(LED1 , OUTPUT);
pinMode(LED6 , OUTPUT);
pinMode(LED7 , OUTPUT);

Serial.begin(9600);

}

void loop()
{
digitalWrite(trig , HIGH);
delayMicroseconds(1000);
digitalWrite(trig , LOW);

duration = pulseIn(echo , HIGH);
distance = (duration/2) / 28.5 ;
Serial.println(distance);

if ( distance <= 200 )
{
digitalWrite(LED1, HIGH);
}
else
{
digitalWrite(LED1, LOW);
}
if ( distance <= 100 )
{
digitalWrite(LED6, HIGH);
}
else
{
digitalWrite(LED6, LOW);
}
if ( distance <= 100 )
{
digitalWrite(LED7, HIGH);
}
else
{
digitalWrite(LED7, LOW);
}
}

Read i want to filter Red is what i want to filter
5
5
5
5
4
4
4
4
2
2
104
222
5
5
5
5
5
5
5

2

I think you need to keep a few past samples, and then compare each incoming reading with
those a few samples back - if the difference is more than some threshold (to be determined),
then ignore the reading.

You have to be careful that the method used can't get jammed when the input validly varies
rapidly.

3

You could also use the NewPing library and its median method - it is good for filtering out the occasional outlier.

4

Thank you this worked