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Tuning guide

Why does my quad wobble on hard stops?

The stop is the same; the cause is not. Four different faults all look like a twitch when the quad comes out of a punch, and they need different answers. This is how to tell them apart in a blackbox log before changing a setting.

1. The stop exposes the fault; it does not create it

A hard stop asks the controller to remove a large amount of angular momentum quickly. If the build has a weakness — a motor that is slow to start, an integrator holding an old offset, a frame that rings, or a gain that is already at its limit — the stop is where it becomes visible. That is why the same wobble can appear on a quad that feels fine in a lazy cruise, and why "add more D" is not a diagnosis.

The log gives you three facts that a video does not: the throttle at the moment of the wobble, whether the wobble began during the stick input or after it stopped, and what the motors and integrator were doing at the same time. Those three facts separate the four common causes below.

2. Four faults, four signatures

The table is a map, not a verdict. A single flight can contain more than one of these. The point is to stop treating "wobble" as one symptom with one knob.

3. Read the timeline, not the vibe

Pick the worst stop in the log and zoom in. Answer these in order:

1. What was the throttle doing? If the wobble only exists with the throttle near idle, start with idle and thrust. If it exists at cruise throttle too, it is a control-loop problem.
2. When did the motion start? A ring that grows while the stick is still moving is a gain/phase problem. A single slow return after the stick has stopped is an integrator problem. A burst during a descent is disturbed air.
3. Is it repeatable? One bad stop can be a bump, a prop strike or a gust. A shape that repeats on both roll and pitch, on several stops, is a tune or a mechanical fault.
4. Were the motors near their limit? If the motors were already saturated, the controller had no authority left to stop the rotation. That is a thrust problem wearing a PID costume.

4. What a hard-stop log actually shows

A step-response view is the cleanest way to see the difference. The setpoint trace jumps, then flattens when the stick stops. The gyro trace follows. The shape after the setpoint flattens tells you which fault you have:

• Gyro rises past the setpoint, then rings back. The response is under-damped. The P/D balance and the filtering that feeds it are the suspects.
• Gyro rises, turns early, and settles below the commanded rate. That is steady-state droop: the integrator did not make up the remaining error. It is a different fault from overshoot, and it is not fixed by adding damping.
• Gyro follows during the move, then rotates back after the stick stops. Look at the I-term trace. This is the signature of an integrator that wound up and is now unwinding.
• Gyro is jagged throughout, and the step view looks like noise. The log is not giving you a usable chart. Fix the log or the mechanics before reading a gain from it.

5. The order that does not lie to you

1. Rule out the build. Cracked prop, loose motor screw, bent bell, a battery strap that can move, a camera mount flapping. These produce log shapes that no PID value can remove.
2. Look at noise before gains. If the gyro is noisy, the controller is reacting to vibration as well as to your input. Filter and mechanical work comes before raising authority.
3. Decide which fault you have. Bounce, droop, propwash and idle instability point at different families. Choose one family from the log, not from a list of settings.
4. Change one family, then re-log the same maneuver. A change you cannot compare against a before-log is a guess with extra steps.
5. Verify on the bench and in a hover. Motor temperature and a short hover tell you things the log cannot. If the motors got hotter, the change is not automatically an improvement.

6. What not to do

• Do not add D to every wobble. D is for one of these faults. On a bounce caused by the integrator, or on a low-throttle thrust problem, it changes the symptom without fixing the cause.
• Do not lower P because the quad bounced back. A slow bounce after the move is often the integrator, and lowering P can make tracking worse while leaving the bounce in place.
• Do not tune from a hover-only log. A hover has no hard stop to measure. It can tell you about noise and mechanical health; it cannot tell you how the quad stops.
• Do not change the tune and the props in the same flight. Then the next log cannot tell you which change produced the result.

7. What Easyquadtune does with a stop

The analyser finds a clean step in the log, aligns the gyro to the setpoint, and reports per axis whether the response overshoots or settles below the command. It also looks for post-maneuver integrator activity and for a noisy gyro, because those change the answer. It does not turn the four faults into one score: a quad can overshoot on roll and droop on pitch in the same flight, and averaging those into a single number would hide the only useful information.

When the log cannot support a gain decision, the result says so — the trust label drops to Partial or Not safe, and the suggested changes shrink toward the mechanical and filter work the log can actually justify. That is deliberate. A confident number from an unreadable chart is worse than an honest "fly a better log".

Questions pilots actually ask

Why does my quad only wobble when I cut the throttle?

Because that is when the motors are closest to their minimum and a small RPM change is a large fraction of the thrust available. Check minimum throttle, dynamic idle, prop size, ESC start-up and any sign of desync before you touch the PID gains.

Is a wobble at the end of a flip always too much P?

No. A fast ring during the move points at the P/D balance. A single slow rotation back after the stick has stopped points at the integrator, and is often made worse by I-term relax being too weak for the build.

Can I diagnose it without a blackbox log?

You can try changes and judge them by feel, but you cannot separate the causes reliably. The useful evidence is the order of events, and a log records it.

Should I tune it out with more D?

Only if the log shows an under-damped response on a clean gyro. Adding D to an integrator bounce or a low-throttle thrust problem does not address the cause, and it can make the motors hotter.

Where these questions come from

The wording and the failure modes here are drawn from public pilot discussions, not from a customer log. Useful primary references:

• Betaflight 4.3 Tuning Notes — bounceback, low-throttle wobble and the distinction between them.
• Betaflight: I-term Relax Explained — what relax does and why the cutoff direction is counter-intuitive.
• Betaflight PID Tuning Tab — the official description of the damping, tracking and stick-response sliders.
• r/fpv: "Fixing dat wobble?" — a pilot describing the post-punchout twist and the answers the community gave.
• IntoFPV: PID tuning cheatsheet — the long-running community summary of bounceback and propwash symptoms.

More guides: how to read a blackbox log, overshoot vs droop, frame resonance vs prop noise, I-term relax, dips in fast turns, when a log is not good enough.

Easyquadtune is not affiliated with the Betaflight project. Always fly responsibly and perform an initial hover test in a safe environment after any tuning change. The worked example on this site is an illustrative render, not a customer log.