Placeholder recovery
4%
Problem
What the build needed to solve
My contribution
Built the 6-DoF recovery model, imperfection sweep, mixer-authority model, exact confidence-bound gate, component/resource map, and propulsion-bench safety protocol.
A small quad may recover in one nominal simulation while failing across CG error, motor mismatch, latency, noise, and battery sag. The project needs a measurement that decides whether the physical authority premise is viable before more hardware spending.
Constraints
Design boundaries
Sub-250 g guarded vehicle and 3.0 m recovery-height budget.
Measure all six motors at 8.4, 7.6, and 7.0 V.
Fifth-percentile authority must reach 0.020 N·m throughout 25–75% collective.
Wave 2 remains blocked until the fixed statistical and safety gates pass.
Build log
Design evolution
Iterations, issues, and fixes documented as a compact notebook timeline.
Revision
Failure mode
Design change
Result
Nominal recovery
A single 60°, 2 rad/s run recovered and could be mistaken for robustness.
Added CG, mass, inertia, motor, latency, noise, and sag dispersions.
The as-toleranced placeholder case recovered only 4% at 2 rad/s.
Mixer prediction
The independent 0.004 N·m torque clip ignored real differential mixer headroom.
Modeled collective-dependent four-motor authority and attitude-priority desaturation.
The assumed 60 mm mixer recovered all 300 original trials.
Measured decision
“Adequate authority” and “sufficient trials” were soft gates.
Frozen 0.020 N·m and 962/1,000 exact-confidence thresholds plus a LiPo bench checklist.
Wave-2 spending is mechanically tied to measured evidence.
Testing
Results
Mixer prediction
300/300
Authority gate
0.020 N·m
Primary trials
1,000
Required successes
962
Measured result
Pending
The authority gate uses all six motors, five collective points, and the empirical fifth percentile at 7.0 V.
If authority passes, the fixed 2 rad/s case must achieve at least 962/1,000 recoveries, exact one-sided 95% lower bound ≥0.95, and maximum descent ≤3.0 m.
Scope note: No hardware, propulsion, tethered recovery, or flight result is claimed yet. The 300/300 mixer result uses assumed arm and datasheet thrust.
Reflection
Engineering lessons
- A robustness failure can identify the one measurement that matters most.
- Static thrust times arm validates authority, not dynamic recovery by itself.
- Safety and spending gates belong in the experiment design before hardware arrives.
Gallery
CAD, fabrication, and test views
Preliminary Simulation
Preliminary simulated recovery envelope; measurement and flight validation remain pending
Simulation result
Simulated altitude lost versus initial tumble rate against the 3 m budget, and max recoverable rate by BOM tier. Assumed-authority regime; bench measurement pending.
Links