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MUSTAFA SERDAR SÖKMEN
MUSTAFA SERDAR SÖKMEN

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When State Estimation Fails: How UAVs Actually Crash

When a UAV crashes, people often blame:

The pilot

The controller

The AI

But in reality, most crashes begin much earlier — and much quieter.

They start when the system loses confidence in its own state.

🧠 Control Rarely Fails First

Modern flight controllers are robust.
PID loops don’t suddenly “forget” how to stabilize.

What fails first is the input to those controllers:

Wrong attitude

Wrong velocity

Wrong position

Garbage in — crash out.

🌫️ How Estimation Slowly Breaks

State estimation rarely fails catastrophically.
It degrades.

Common patterns:

IMU bias slowly accumulates

GPS latency increases

Magnetometer gets disturbed

Vibrations leak into accelerometers

Each error is small.
Together, they move the system away from reality.

⚠️ The Most Dangerous Moment

The most dangerous phase is not aggressive flight.

It’s hover.

Why?

Low dynamics hide errors

Filters get overconfident

Biases grow silently

Then a sudden maneuver happens —
and the estimated state no longer matches physics.

🔄 Control Obeys the Wrong Reality

The controller is not “wrong”.
It is doing exactly what it was designed to do.

The problem:

It is stabilizing a state that does not exist.

From the controller’s perspective, the crash makes perfect sense.

🤖 Why AI Can Make This Worse

AI-based perception can:

Mask estimation errors

Delay detection

Add false confidence

An AI model may say:

“Everything looks normal.”

While the estimator is already drifting.

🧩 Real Crash Logs Tell the Same Story

If you read enough flight logs, you see patterns:

Sudden attitude jumps

Velocity spikes

Position corrections too late

Crashes are not surprises.
They are unnoticed divergences.

💭 Final Thought

UAVs don’t crash because control fails.

They crash because:

The system stops knowing where it is — and keeps flying anyway.

Understanding this difference is what separates pilots from engineers.

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