Good day, I have the following code for an ultrasonic sensor that I'm using, but the result is not being accurate and I'd like to display the distance from the target in centimetres.
#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
}
I will appreciate any help.
Convert inches to centimeters by multiplying by 2.54
float targetDistanceCentimeters = targetDistance*2.54;
Your code looks correct, so my guess is that this is a hardware problem. In my experience ultra sound sensors are typically quite bad at measuring distance to any object that is not a wall or other large object with relatively flat surface. So if you want to test the accuracy of your system, test it against such object i.e. wall or book. If your sensor is moving while making the measurements make sure that it is not moving too fast. If you are measuring distance to small or thin object you will need to filter and take the average of the measurements. It’s all up to you how accurate you want to be, I’d say that average of twenty or so of filtered measurements will give you appropriate result.
Another things to consider is that you have the correct supply voltage and that the sensor is not directed against the floor at some angle, as this might give unwanted reflections.