Forge System README

Overview

The Forge system was developed for the 2025 NASA University Student Launch Initiative (USLI) competition by the James Madison University team. The Forge class provides a system for monitoring and analyzing data from the payload onboard the Vulcan I rocket. This system collects data from sensors, calculates critical metrics such as maximum altitude, velocity, and G-forces, and transmits the results via APRS. It also evaluates the survivability of onboard STEMnauts based on the collected data.

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Features

• Altitude Monitoring: Tracks and records the maximum altitude (apogee) using a BMP sensor.
• Velocity Calculation: Calculates the velocity based on altitude changes.
• G-Force Measurement: Measures high-G accelerations and determines maximum G-forces sustained.
• Temperature Recording: Records the temperature at the landing site.
• Orientation Tracking: Uses quaternion data from a BNO055 absolute orientation IMU to record orientation.
• Battery Status: Reports battery status.
• Survivability Assessment: Calculates the likelihood of onboard STEMnauts' survival based on velocity, G-forces, and temperature.
• Data Transmission: Sends telemetry data via APRS.
• Shutdown Mechanism: Includes a shutdown feature triggered by a specific PWM signal.

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Sensors Used

• Ublox MAX-M8Q GPS: For time and position data.
• Adafruit BMP085: For altitude readings.
• Dorji DRA818V: For transmitting data via APRS.
• LightAPRS 2.0: A microcontroller integrated with the GPS, altimeter, and radio listed above.
• Adafruit BNO055: Absolute orientation IMU for orientation tracking.
• Adafruit ADXL375: High-G accelerometer for G-force measurements.
• TMP36: Thermistor for temperature measurements.

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Installation

1. Clone the repository and include the required libraries in your Arduino environment:

   • Adafruit BMP085 Library
   • Adafruit Sensor Libraries
   • CircularBuffer
   • SparkFun Ublox Arduino Library
   • ZeroAPRS Library

2. Ensure the sensors are correctly wired to the microcontroller as per their datasheets.

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Usage

Initialization

The Forge object is instantiated using its constructor, which initializes the onboard sensors and sets default values for key variables.

Core Functions

• Altitude and Velocity:

  • getAltitude(): Reads the current altitude.
  • isMaxAltitude(): Updates the maximum altitude if the current altitude exceeds the previous value.
  • getVelocity(): Calculates the velocity from changes in altitude.
  • isMaxVelocity(): Updates the maximum velocity if the current velocity exceeds the previous value.

• G-Force Measurement:

  • getGforce(): Updates the current G-force using acceleration data.
  • isMaxGforce(): Updates the maximum G-force if the current value exceeds the previous maximum.

• Landing Conditions and System Status:

  • recordTime(): Records the time of landing.
  • calculateLandingVelocity(): Calculates the landing velocity based on 3 seconds of acceleration data recorded at and just before landing.
  • recordTemperature(): Records the temperature at the landing site.
  • recordOrientation(): Records the orientation of the onboard STEMnauts.
  • recordBatteryStatus(): Records the status of the battery.

• Survivability:

  • calculateSurvivalChance(): Evaluates the survival chances based on landing velocity, G-forces, and temperature.

• Data Transmission:

  • transmitData(): Sends telemetry data over APRS.

• Shutdown:

  • getShutdownStatus(): Determines if a shutdown signal has been received.
  • shutdown(): Simulates shutdown by pausing operations for 10 seconds (this get looped infinitely).

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Data Format

Telemetry Data sent through APRS

The system generates telemetry data in the following format to be sent as an APRS status messages with a small delay between transmissions:

• Temperature of Landing Site: X°C
• Apogee reached: Y m
• Power Status: true/false
• Orientation of On-Board STEMnauts: W, X, Y, Z (Quaternions)
• Time of Landing: MM/DD/YYYY|HH:MM:SS.NANO
• Maximum Velocity: Z m/s
• Landing Velocity: A m/s
• G-Forces Sustained: B G
• Calculated STEMnaut Crew Survivability: Yes/Yes but hurry/Unlikley

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Configuration/User-Defined Settings

APRS Call Sign

Modify the CallSign variable to your CallSign:

char CallSign[7] = "YOURCALL";

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APRS Frequency

Set the operating frequency based on your use case:

char Frequency[9] = "144.3900";

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Shutdown Threshold

Adjust the PWM duty cycle threshold for initiating shutdown as needed:

const int shutdownThreshold = 50;

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Notes and Limitations

    1. Ensure all sensors are properly calibrated before deployment.
    2. The system currently uses a rule of thumb for the battery status (if we can transmit, than the battery is working).