Can anyioue build and code an arduino based thrust test tool using a force / strain gauge and arduino ?
There are loads of them on the internet and I tried making one but cant get it to work
What does not work ?
it's basically reading as fast as you can in a tight loop the readings from the strain gauge and printing that out to the Serial monitor.
what’s your current status and test stand setup?
Adafruit has some great tutorials: Adafruit HX711 24-bit ADC for Load Cells / Strain Gauges : ID 5974 : Adafruit Industries, Unique & fun DIY electronics and kits
I didnt get any of it to fire up basically I was hoping I could pay someone in here to assemble all my bits or supply all the bits working and coded so all I have to do is mount the load sensor and circuit boards/ wiring and calibrate it
For reference, the document referred to by the video... schematic and code included
Do you mean the propellant did not "ignite" or the code did not "ignite the propellant?"
Yes it is possible. What do you want to measure, the peak force, average force or plot it on a curve, each can be measured but the processing power and hardware change. For example I would use a peak detector or peak sample and hold in front of the Arduino input, reason the sample frequency may be longer then the maximum thrust period and what part of the you sample will change your results. Here is a sample of that the curve would look like:
I would like to plot a thrust / time curve and record peak thrust similar to the device in the following video
thats what I tried but my arduino is just blank and I dont want to spend days learning how to put it together - I just want someone to sell me the hardware with the coded arduino...
Okay... but whoever accepts your offer will take more than days.
Just for fun... let's share the code... and see what we can find...
The PDF mangled the code, but I did not see this...
scale.begin(DOUT, CLK); // missing from original code
Once I unmangled the code in the PDF, I got this...
/*
Model Rocket Engine Dynamometer - Nick Cinquino 9/1/15 - V.5 Original lOKg loadcell
Modified from Nathan Seidle, SparkFun Electronics, November 19th, 2014
Output data in grams (g). There are 101 .97 gram-force per Newton, for conversion.
Your calibration factor may be very positive or very negative. It all depends on the
setup of your individual loadcell, and the direction the sensors deflect from zero state.
Need to experiment!
Hack the HX71 1 board to set pin 15 high, for 80 samples per second.
This example code uses bogde's excellent library: https://github.com/bogde/HX711
bogde's library is released under a GNU GENERAL PUBLIC LICENSE
Arduino
pin 2 - HX71 1 Clock
pin 3 - Serial Data In
5V - VCC
GND - GND
Yellow LED on pin 13
Igniter transistor/relay on pin 11
Momentary pushbutton on pin 12
Most any pin on the Arduino Uno will be compatible with DOUT/CLK.
The HX71 1 board can be powered from 2.7 V to 5V so the Arduino 5V power is fine.
*/
#include <HX711.h>
#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
const int buttonPin = 12; // start sequence button
const int ledPin = 13; //LED indicator and/or buzzer
const int igniterPin = 11; //igniter transistor circuit
int buttonState = 0;
#define DOUT 3
#define CLK 2
HX711 scale; // HX711 scale(DOUT, CLK); // wrong in original code
float calibration_factor = -560; //-560 works for my 10kg loadcell.
void setup() {
pinMode(buttonPin, INPUT);
pinMode(igniterPin, OUTPUT);
pinMode(ledPin, OUTPUT);
Serial. begin(9600);
Serial.println("HX71 1 Rocket Motor Dynamometer, V.5");
Serial.println ("Affix motor nozzle up. Place igniter in nozzle. Move away from test stand.");
Serial.println("Press start button to initialize ignition sequence.");
lcd.begin(16, 2);
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("MODEL ROCKET");
lcd.setCursor(0, 1);
lcd.print(" DYNAMOMETER");
delay(2000);
scale.begin(DOUT, CLK); // missing from original code
scale.set_scale();
scale.tare(); //Reset the scale to 0
long zero_factor = scale.read_average(); //Get a baseline reading
Serial.print("Zero factor: "); //remove need to tare scale. Useful in permanent scale projects.
Serial.println(" ");
Serial.println(zero_factor);
}
void loop() {
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Rocket Dyno");
lcd.setCursor(0, 1);
lcd.print("STDBY " );
scale.set_scale(calibration_factor);
lcd.print(scale.get_units(), 1 );
lcd.print(" g");
delay(500);
buttonState = digitalRead(buttonPin);
if (buttonState == HIGH) {
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Rocket Dyno");
lcd.setCursor(0, 1);
lcd.print("STAND CLEAR!");
Serial.println("lGNITION SEQUENCE ACTIVATED!");
for (int i = 0; i <= 50; i++) {
digitalWrite(ledPin, HIGH);
delay (100);
digitalWrite (ledPin, LOW);
delay (100);
}
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Rocket Dyno");
lcd.setCursor(1, 1);
lcd.print("AQUIRING DATA");
digitalWrite(igniterPin, HIGH);
Serial.print("Start time, ms: ");
Serial.print (millis());
Serial.println(" ");
Serial.println();
for (int i = 0; i <= 800; i++) { //800 samples at 80 samp/sec = 1 0 seconds theoretical
scale.set_scale(calibration_factor); //Adjust to the calibration factor
Serial.print(scale.get_units(), 1 );
Serial.println();
}
Serial.println();
Serial.print("Stop Time, ms: ");
Serial.print(millis());
digitalWrite (ledPin, LOW);
digitalWrite (igniterPin, LOW);
Serial.println();
}
}
/*
Note the line highlighted in yellow: this is the calibration factor that the Arduino uses to convert
the signal from the loadcell/HX71 1 into grams. This value varies widely, even for 2 apparently
identical loadcells! You just have to place a known weight in grams on the loadcell and try some values
until you zero in on the best value that reads your calibration weight in grams on the LCD.
Loadcell/motor mount: This can be designed and built to suit; the general guidelines are, keep it light
(no use in burning up dynamic range), and, importantly, nonflammable! Ours uses a thin sheet steel
circular base (such as the cutout from a coffee can) bolted down to the loadcell, with a cemented
motor tube with retaining clip attached to the center of the steel base. The motor tube is a half inch
longer than the motor, with vent holes at the bottom so that on ejection, the motor moves forward against
the retaining clip while ejection gases escape via the bottom vents. Fig. 5 shows the loadcell with base:
*/
The WHITE LED is the igniter.
So... I think you have good code now... just need to test it.
Just buy one
Did you get the solution for the problem , or else still in stuck, I can help you , Send me the details
Email : ribuwaneka@gmail.com
You should not share your contact details in a public forum. Bots will pick it up.
Use private message at the minimum for this …
Thanks for the advice, but this isn’t my personal email. I keep a separate, dedicated email for sharing on public forums.