View source for Ultrasonic Rangefinder

{{Template:Infobox_Generic
| Name                                        = UltraSonic Rangefinder
| Image                                       = Temp.jpg
| SensorType                                  = Sonic Distance
| IOPins                                      = 4 Pins
| TypicalVoltage                              = 5.0 V
| TypicalCurrent                              = <2mA
| MaxVoltage                                  = 5 V
| MaxCurrent                                  = <2 mA / Pin
Ethernet, USB
| Range                                       = ~2cm-500cm
| Cost                                        = $6.95
| Website                                     = [https://www.amazon.com/SainSmart-HC-SR04-Ranging-Detector-Distance/dp/B004U8TOE6 Device Website]
| Student                                     = [mailto:jpoe@mdc.edu Dr. James Poe]
}}


The Ultrasonic RangeFInder is divided into three broad categories.  Transmitters, Receivers and Transceivers.  The device is used to measure distances by using ultrasounds that work as sonar and return the distance.

== History of Device ==

Ultrasonic devices are inspired from the natural world where many animals use it naturally.


== Purpose of the Device ==

The Ultrasonic RangeFinder is used to measure distances and works by sending and receiving ultrasonic waves.

The device will emit a high frequency sound wave that hits objects and is reflected back into the receiving end and feeds back the distance to the programmed chip.  



== Physical Implementation and Design ==

The device has a basic structure and overall design.  Most ultrasonic rangefinders contain both a transmitter and receiver.  The transmitter works by emitting a pulse of ultrasonic sound that travels through the air until it hits an object.  The reflected sound goes into the receiving end and the device calculates how long it took for the sound to return, thus providing the distance traveled.  

Knowing the time it takes the ultrasonic pulse to travel back and forth to the object, and also knowing the speed of sound, we can calculate the distance to the object. The formula relating the speed of sound, distance, and time traveled is:

speed = distance / time

Rearranging this formula, we get the formula we will use to calculate the distance:

distance = speed x time

The time variable will be provided by the ultrasonic range finder as the time it takes for the ultrasonic pulse to leave the sensor, bounce off the object, and return to the sensor. We actually divide this time in half since we only need to measure the distance to the object, not the distance to the object and back to the sensor. The speed variable is the speed at which sound travels through air.

The speed of sound in air changes with temperature and humidity. Therefore, in order to accurately calculate distance, we will need to consider the local ambient temperature and humidity. The formula for the speed of sound in air that factors in temperature and humidity is:

c = 331.4 + (0.606 x T) + (0.0124 x H)

c = Speed of sound in meters per second (m/s)

331.4 = Speed of sound (in m/s) at 0 °C and 0% humidity

T = Temperature in °C

H = % Humidity (relative humidity)

For example, at 20 °C and 50% humidity, sound travels at a speed of:

c = 331.4 + (0.606 x 20) + (0.0124 x 50)

c =  344.02 m/s.

In the equation above, it’s clear that temperature has the largest effect on the speed of sound. Humidity does have some influence, but it’s much less than the effect of temperature.

== Applications for the Device ==

The main purpose of this sensor is to make sure that it can measure distances properly.  It can be used in order to prevent a movable robot or object from hitting barriers.  The sensor calculates the distance of any object in front of it and reports it back to the controlling chip.


Ultrasonic Range Finders are used in various applications.

-Measuring distance.

-Calculating and preventing a collision.

-Measuring change in distance.

== Schematics to use the Device ==

https://www.arduino.cc/en/uploads/Tutorial/PING_schem.png

== Code to Control the Device ==

#include <LiquidCrystal.h> //Load Liquid Crystal Library
LiquidCrystal LCD(10, 9, 5, 4, 3, 2);  //Create Liquid Crystal Object called LCD

int trigPin=13; //Sensor Trip pin connected to Arduino pin 13
int echoPin=11;  //Sensor Echo pin connected to Arduino pin 11
int myCounter=0;  //declare your variable myCounter and set to 0
int servoControlPin=6; //Servo control line is connected to pin 6
float pingTime;  //time for ping to travel from sensor to target and return
float targetDistance; //Distance to Target in inches
float speedOfSound=776.5; //Speed of sound in miles per hour when temp is 77 degrees.

void setup() {
  
Serial.begin(9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
 
LCD.begin(16,2); //Tell Arduino to start your 16 column 2 row LCD
LCD.setCursor(0,0);  //Set LCD cursor to upper left corner, column 0, row 0
LCD.print("Target Distance:");  //Print Message on First Row
}

void loop() {
  
  digitalWrite(trigPin, LOW); //Set trigger pin low
  delayMicroseconds(2000); //Let signal settle
  digitalWrite(trigPin, HIGH); //Set trigPin high
  delayMicroseconds(15); //Delay in high state
  digitalWrite(trigPin, LOW); //ping has now been sent
  delayMicroseconds(10); //Delay in high state
  
  pingTime = pulseIn(echoPin, HIGH);  //pingTime is presented in microceconds
  pingTime=pingTime/1000000; //convert pingTime to seconds by dividing by 1000000 (microseconds in a second)
  pingTime=pingTime/3600; //convert pingtime to hourse by dividing by 3600 (seconds in an hour)
  targetDistance= speedOfSound * pingTime;  //This will be in miles, since speed of sound was miles per hour
  targetDistance=targetDistance/2; //Remember ping travels to target and back from target, so you must divide by 2 for actual target distance.
  targetDistance= targetDistance*63360;    //Convert miles to inches by multipling by 63360 (inches per mile)
  
  LCD.setCursor(0,1);  //Set cursor to first column of second row
  LCD.print("                "); //Print blanks to clear the row
  LCD.setCursor(0,1);   //Set Cursor again to first column of second row
  LCD.print(targetDistance); //Print measured distance
  LCD.print(" inches");  //Print your units.
  delay(250); //pause to let things settle
  
  
  }

== Video of the Device on Operation ==

https://www.youtube.com/watch?v=ZejQOX69K5M

== Different Version of the Device ==

== Where to Purchase Device ==

Device name	                 Website	        Price	      Link to product page

Maxbotix Ultrasonic Rangefinder	 Adafruit	        $24.95	     https://www.adafruit.com/products/172

HC-SR04 Ultrasonic Range Finder  RobotShop              $ 2.50       http://www.robotshop.com/en/hc-sr04-ultrasonic-range-finder.html

SainSmart Ranging Detector Mod   Amazon	                $ 6.95	     https://www.amazon.com/SainSmart-HC-SR04-Ranging-Detector-Distance/dp/B004U8TOE6

== References ==

https://www.arduino.cc/en/Tutorial/Ping

https://www.youtube.com/watch?v=Tje6F6oOX8I

http://www.buildcircuit.com/ping-ultrasonic-range-finder-on-breadboard-using-arduino/

http://www.circuitbasics.com/how-to-set-up-an-ultrasonic-range-finder-on-an-arduino/

https://www.vexrobotics.com/wiki/Ultrasonic_Range_Finder