¶ Control and Redundancy Architecture
To ensure high-integrity operation and passenger safety, the system is split into two specialized control nodes.
- Role: Flight dynamics, active buoyancy control, and energy harvesting.
- Key Tasks: PID loops for leveling, altitude station-keeping, MPPT management, and tether tension monitoring.
- Communication: Primary LoRa link to ground; ESP-NOW / Hardwired Serial link to the Vest MCU.
- Role: Life support monitoring, passenger interface, and Winch Control.
- Winch Control (VFD-C): Dedicated power stage for the Active Tensioning Winch.
- Sensors:
- Tension Sensor: Load cell monitoring real-time tether stress.
- Vitals: Pulse Oximeter (MAX30102) and Heart Rate monitoring.
- Environment: Internal vest temperature and O2 concentration sensors.
- Haptics: Vibration motors for "Altitude Limit" or "Battery Low" alerts.
- Emergency: Houses the primary Master Kill Switch.
Buoyancy is life. The system must survive a partial heater failure.
- Each of the three balloons contains two independent Nichrome circuits.
- Circuit Alpha: Primary lift maintenance.
- Circuit Beta: Redundant backup; can be overdriven in emergencies to compensate for a total failure in an adjacent balloon.
To prevent a "dead balloon" from causing an unrecoverable tilt, a pneumatic link system is proposed:
- Hot-Air Manifold: Lightweight, insulated silicone tubing connecting the three balloons.
- Check-Valves/Fans: Small, low-power inline fans can move air between balloons to equalize temperature if one balloon's heaters fail.
- Benefit: Ensures that heat generated in Balloon 1 can contribute to the buoyancy of Balloon 2, maintaining symmetric lift.
The Kill Switch is a multi-stage emergency system routed directly to the passenger's vest.
- Stage 1 (Software): Passenger toggle to "Initiate Safe Descent" (PID-controlled reduction in heat).
- Stage 2 (Hardwired Kill): A physical pull-pin or guarded switch on the vest that:
- Cuts power to all heating elements.
- Triggers the Emergency Vent Solenoid (Burn-wire or valve) on the balloons.
- Deploys the Drogue Parachute for a stabilized (though rapid) descent.
- Heartbeat Protocol: The Platform MCU and Vest MCU exchange a 10Hz "Heartbeat."
- Vest-Lost-Link: If the Platform loses the Vest MCU signal, it automatically enters "Hold Altitude" and initiates a slow 0.5 m/s descent.
- Platform-Lost-Link: If the Vest loses the Platform signal, it alerts the passenger via high-intensity haptics and audio.
Last updated 2026-06-09.