Sisyphus — Subsystem
Flight Stages
The flight software runs through three stages: countdown, stabilizing ascent, and descent/recovery.
- Software tells the flight computer how to react to sensor inputs and command hardware outputs.
- Code coordinates countdown, powered ascent, descent detection, and recovery actions.
- Real-time logic links IMU/barometer estimates to TVC control and pyro events.
Countdown
- A multi-press gate starts launch countdown.
- An audible buzzer countdown and LED cues signal launch timing.
- Gyro calibration and barometric zero are finalized before ignition.
- At countdown completion, the ignition channel is fired.
Stabilizing Ascent
- Dual-axis TVC runs a PD stabilization loop using angle and angular-rate feedback.
- Control outputs are constrained and mapped to servo geometry for stable actuation.
- Sensor fusion and altitude-rate tracking inform stage transitions and safety checks.
- If tilt exceeds safe bounds, emergency recovery logic is triggered.
Descent and Recovery
- Once descent is detected, the controller transitions to recovery behavior.
- Recovery development is currently split between validated parachute recovery and in-progress propulsive recovery.
- Final status cues are provided through onboard buzzer and LEDs.
Parachute Recovery
- Parachute deployment is currently the flight-proven recovery path.
- Descent detection and staged recovery events are integrated in the live flight code.
- This mode provides a reliable fallback while propulsive recovery matures.
Propulsive Recovery (In Progress)
- This recovery mode is actively under development and is not yet flight-proven.
- Current work focuses on transitioning from parachute-only recovery to powered terminal recovery.
- Low-altitude state transitions, throttle-window timing, and attitude constraints are still being iterated.
- Target outcome: controlled touchdown using active TVC authority through the final descent phase.