So I have been working on this project for a few months now. It goes as follows:
Task: Detect when the rocket has reached apogee, then deploy a parachute.
Here are some pictures of the finished product.
And here is a video of a working trial.
So my issue is, the system is not 100% reliable, nor does it deploy fast enough. As seen in the video, the rocket falls a good distance before the parachute is deployed.
So, I'm positive it's something with the code I've written up. Here it is. Feel free to butcher it all you want, I'm no way an expert at programming, but I'd say I'm decent.
General description of what the code is doing:
It first initializes sensors, LED's, and the sd card reader.
it then begins to read the altitude with no delay until it notices that the altitude since its last check has dropped by 1 meter. It then waits 150ms (slightly more than the speed of gravity) to allow for another 1 meter drop. It then waits another 150ms to be 100% sure it's dropping. If it passes all 3 checks the servo is turned and the parachute is deployed.
Here is the code:
#include <SPI.h>
#include <SD.h>
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP085_U.h>
#include <Servo.h>
File myFile; //creates a file to be written to
Adafruit_BMP085_Unified bmp = Adafruit_BMP085_Unified(10085); // sets up the BMP180
int altitude;
int lastAltitude;
int apogee; // Stores max altitude for total height
int groundAltitude; // Stores starting altitude, before launch
int maxHeight;
byte chipSelect = 4; // for sd card reader
int groundTemp;
int apogeeTemp;
int tempChg;
float temperature;
Servo myservo; // Creates servo object
byte yellowLed = 3;
byte redLed = 2;
void setup() {
pinMode(yellowLed, OUTPUT);
pinMode(redLed, OUTPUT);
Serial.begin(9600); // Begins the serial monitor for debugging
pinMode(4, OUTPUT); // for sd card
Serial.print(F("Initializing SD card..."));
pinMode(10, OUTPUT);
if (!SD.begin(4)) {
Serial.println(F("initialization failed!"));
digitalWrite(redLed, HIGH);
return;
}
Serial.println(F("initialization done."));
myFile = SD.open("data.txt", FILE_WRITE);
myFile.println(" ");
myFile.println("Starting data logging");
myFile.println("---------------------");
delay(50);
myFile.close();
if(!bmp.begin()) // Initializes the BMP180
{
while(1);
}
myservo.attach(9); // Mounts the servo to pin 9
myservo.write(20); // Writes starting pos of servo
sensors_event_t event; // Starts a reading
bmp.getEvent(&event);
groundAltitude = bmp.pressureToAltitude(1013,event.pressure); //reads altitude
bmp.getTemperature(&temperature); //reads temp
groundTemp = temperature;
myFile = SD.open("data.txt", FILE_WRITE);
myFile.print(F("Altitude before Launch was "));
myFile.print(groundAltitude);
myFile.println(F(" meters."));
myFile.print(F("Temperature before launch was "));
myFile.print(groundTemp);
myFile.println(F(" Degrees C."));
myFile.close();
digitalWrite(yellowLed, HIGH);
digitalWrite(redLed, LOW);
}
void loop() {
getAltitude(); // Gets current altitude
if(altitude - lastAltitude <= -1) // Checks for a 1 meter drop in altitude
{
Serial.println(" TRIGGERED, MUST BE VERIFIED");
delay(150); // Gravity is 0.102ms per meter, so 150ms is enough to compensate for drag.
getAltitude; // Gets a new altitude reading
if(altitude - lastAltitude <= -2) // Checks if new altitude reading is 1 meter less than last measured
{
Serial.println(" TRIGGERED 2, MUST BE VERIFIED");
delay(150); // Gravity is 0.102ms per meter, so 150ms is enough to compensate for drag.
getAltitude; // Gets a new altitude reading
if(altitude - lastAltitude <= -3) // Checks if new altitude reading is 2 meters less than last measured
{
myservo.write(180); // Moves servo to deploy parachute
Serial.println(" DEPLOYING");
bmp.getTemperature(&temperature);
apogeeTemp = temperature;
myFile = SD.open("data.txt", FILE_WRITE);
myFile.println("Parachute deploying!");
myFile.close();
apogee = lastAltitude;
apogee = apogee - 3;
maxHeight = apogee - groundAltitude;
tempChg = groundTemp - apogeeTemp;
Serial.print(F("Parachute has been deployed. Max Height of rocket was "));
Serial.print(maxHeight);
Serial.println(F("meters"));
myFile = SD.open("data.txt", FILE_WRITE);
myFile.print(F("Max Height of rocket was "));
myFile.print(maxHeight);
myFile.println(F("meters."));
myFile.print(F("The altitude at apogee was "));
myFile.print(apogee);
myFile.println(F("meters"));
myFile.print(F("The temperature at apogee was "));
myFile.print(apogeeTemp);
myFile.println(F(" C"));
myFile.print("There was a ");
myFile.print(tempChg);
myFile.print(F(" degree C change from launch to apogee"));
myFile.close();
while(1)
{
digitalWrite(yellowLed, LOW);
delay(1000);
digitalWrite(yellowLed, HIGH);
delay(1000);
}
}
else
{
lastAltitude = altitude; // False reading. Sets current altitude to the last measured altitude
Serial.println(" Didnt fall, 3");
}
}
else
{
lastAltitude = altitude; // False reading. Sets current altitude to the last measured altitude
Serial.println(" Didnt fall, 2");
}
}
else
{
lastAltitude = altitude; // False reading. Sets current altitude to the last measured altitude
Serial.println(" Didnt fall");
}
}
void getAltitude() // Reads the BMP180 and returns an altitude in meters
{
sensors_event_t event; // Starts a reading
bmp.getEvent(&event);
altitude = bmp.pressureToAltitude(1013,event.pressure); // Sets the altitude to int 'altitude'
Serial.print(altitude); // Prints Altitude to Serial monitor
Serial.println( "meters");
}
So any help of making this system any faster/ reliable would be very helpful! Thanks so much!
