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I am working on a project in which I want to calculate the speed of a toy car using an ultrasonic sensor by measuring the distance and once it reaches the end. We see the time that has passed from when the programme has started. However I have discovered that the sensor I am using is accurate only till 20cm. Any suggestions?

#include <NewPing.h>

int i=0;
float distance;
long duration;
int trigpin = 9;
int echopin = 10;
int s;
boolean warrant=true;
unsigned long time;
void setup() {
// put your setup code here, to run once:

pinMode(trigpin, OUTPUT);
pinMode(echopin, INPUT);
Serial.begin(9600);
}
void loop() {
// put your main code here, to run repeatedly:
// put your main code here, to run repeatedly:
time=millis();
if(warrant==true){
s=distance;

digitalWrite(trigpin, LOW);
delay(2);
digitalWrite(trigpin, HIGH);
delay(10);
digitalWrite(trigpin, LOW);
duration = pulseIn(echopin, HIGH);
distance = duration * 0.034 / 2;

if((distance-s)>1){
Serial.println(distance);
}
delay(200);
if(distance>30){
 Serial.println(distance/time);
Serial.println("done");
delay(10);
warrant=false;

 }}}

Ideally it should measure the speed easily. The code is working perfectly but it breaks down after 20cm. Probably due to the sensor's limitations

Kara
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Satyam Ohlan
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  • What you could try is apply the formula of speed, see [this link](https://physics.info/velocity/) for more details. But basically you would get your distance and how long was your time... Something like `end_distance - start_distance / time_for_do_it` – Esdras Xavier Apr 15 '19 at 16:59

1 Answers1

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If the sensor is accurate only until 20cm and you need to measure bigger, you should have to change the sensor for a better one. The is no code that can make your sensor better.

Shark
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