What is the difference between overshoot and steady-state droop?

Overshoot is the gyro passing the commanded rate and then coming back, usually with ringing. Droop is the gyro stopping short of the commanded rate and staying there while the stick is still held. Overshoot is a damping and P/D-balance question. Droop is a steady-state error question, which points at the integrator or at I-term relax holding I down.

Why is my step response chart flat or jagged?

The log did not contain a clean, measurable step on that axis. Common causes are a hover-only flight, a step hidden inside a flip or roll, a stick input that was too small to resolve, a sampling rate too low for the window, or a gyro dominated by noise. A flat or jagged chart is not evidence of a good tune; it is evidence that the tune was not measured.

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Overshoot vs droop

Q: What does a step response actually plot?

It plots two time-aligned traces over a short window around a fast stick input: the commanded rate (setpoint) and the rate the gyro measured. The traces are usually normalised so the commanded step is the reference, which lets one shape be compared across axes and flights. It is an estimate built from one or more moves, not a laboratory step test.

Q: Should I tune to a target overshoot percentage?

A target copied from another quad is not a measurement of yours. Feedforward, stick speed, rates, throttle and motor saturation all change the peak. Compare the shape against your own earlier logs and against a flight that used the same maneuvers, then let the direction of the error decide which family to inspect. The number alone does not tell you which gain is wrong.

Two step-response curves can look similar in a screenshot and mean opposite things. One peaks above the command and rings back; the other stops short and stays there. Read the plateau before you read the peak.

1. What the chart is

A step response is a short time window around a fast stick input. The horizontal axis is time from the start of the move. The vertical axis is rate, normalised so the commanded step becomes the reference. One line is the setpoint — what the sticks asked for — and the other is the gyro, which is what the frame actually did.

It is an estimate, not a laboratory test. A single logged move can be noisy, so analysers either pick a representative clean step or average many windows across the flight. That choice matters: an average over unlike moves can smooth away the fault you are looking for, while a single hand-picked move can be unrepresentative. The useful question is not "what is the peak value" but "what shape repeats".

2. The four measurements that matter

Rise time — how long the gyro takes to get from the first part of the response to most of the way there. A long rise with a clean shape is sluggish; a short rise with a violent peak is not automatically better.
Overshoot — how far past the commanded rate the gyro goes. The peak alone is not a diagnosis: a full-stick snap includes a large feedforward contribution that a gentle flick does not.
Settling and ringing — whether the response calms down quickly or keeps oscillating. Ringing after the peak is a damping problem; a single slow return is often an integrator problem.
Steady-state ratio — where the response levels off while the stick is still held. This is the measurement most people skip, and it is the one that separates droop from overshoot.

3. The two faults that look alike

What you see	What it means	Where to look
Peaks above the command, then rings back	Under-damped: too much gain for the phase left after filtering, or not enough damping	The P/D balance, the filter delay feeding it, and whether the gyro was clean enough for D to be useful
Levels off below the command and stays there	Steady-state error: the integrator did not make up the remaining difference	I and `iterm_relax` — relax deliberately holds I down during fast moves, and too much suppression looks exactly like too little I
Rises, turns early, then slowly creeps up to the command	The integrator is doing the work after the fast terms have finished	I authority and relax timing, not the D gain
Peak is high but the curve settles immediately without ringing	Mostly feedforward and stick speed, not a P/D fault	Whether the move was a full-stick snap; compare with a smaller flick

The plateau is the honest part of the chart. A peak can be produced by feedforward, a fast stick, or a single unrepresentative move. A response that sits below the command for the whole held portion is telling you the controller never caught up. That needs a different answer from a response that overshoots.

4. Why a peak can mislead you

Feedforward responds to how fast the stick moves. A full-stick snap is about as fast as a stick can move, so feedforward contributes a large part of the peak. The same quad flown with a slower, smaller input may overshoot much less. If you tune the overshoot of a full-stick snap down to a number copied from someone else's quad, you may be tuning the stick speed rather than the control loop.

Other confounders:

Rates and expo change the setpoint shape, so two logs with different rate profiles are not comparable.
Throttle and TPA change the gains during the move. A step taken at high throttle is not the same test as one at hover.
Motor saturation caps the correction. A quad that runs out of authority cannot follow the command no matter what the gains are.
Filter delay shows up as a late rise and a phase-limited overshoot. Lowering a filter may improve the chart while making the quad fly worse.
Propwash and bumps add gyro motion that the controller did not command. Trim them out before reading the step.

5. What a chart that is too noisy to decide from looks like

A usable step chart has a clear command edge, a gyro trace that follows it, and a held portion long enough to see where the response settles. A chart that cannot support a decision usually has one of these shapes:

Flat lines. No clean step was found on that axis. The analyser is not showing a perfect tune; it is showing an absence of measurement.
Jagged trace with no clear edge. The input was too small, the gyro was dominated by noise, or the window is mostly turbulence. Fitting a gain to this is fitting noise.
Only one axis has a chart. A log full of rolls and flips may produce a roll step and no clean pitch step. The pitch answer is missing, not neutral.
The curve never reaches a held portion. If the stick was released before the response settled, there is no plateau to measure, so droop cannot be assessed.

In each case the correct action is to fly a better log, not to choose a smaller adjustment and hope. A conservative change based on an unreadable chart is still a change based on nothing.

6. The flight that produces a readable chart

Hover with the sticks centred and the throttle steady.
Make one quick roll flick, then return the stick to centre and pause.
Do the same on pitch, separately, without rolling at the same time.
Repeat several times per axis, with a pause between moves.
Keep the throttle similar across the moves so the comparison is fair.
Keep flips, crashes, prop strikes and low-altitude turbulence out of the analysed section.

Rolls and flips are not a substitute for isolated flicks. A flip couples roll and pitch and often ends with the motors near saturation, which is exactly the condition that makes a step chart unrepresentative.

7. How Easyquadtune reads the chart

The analyser reports each axis separately. It measures overshoot, rise time, tracking error and the steady-state plateau, then labels the chart as usable, weak or unusable. A weak axis contributes less to the suggestion; an unusable axis contributes nothing, because there is nothing measured to contribute. Droop is only treated as evidence when the chart is clean and the response genuinely levels off below the command — otherwise too much damping could be mistaken for too little integrator.

That is also why the output is per-axis rather than one "tune quality" score. A quad can overshoot on roll and droop on pitch in the same flight. One number would average those into a middle that describes neither axis.

Questions pilots actually ask

What does a step response actually plot?

Two time-aligned traces around a fast stick input: the commanded rate and the measured gyro rate, normalised so the command is the reference. It is an estimate from one or more moves, not a lab test.

What is the difference between overshoot and droop?

Overshoot passes the command and comes back. Droop stops short and stays there while the stick is still held. Overshoot is a damping question; droop is a steady-state error question.

Why is my chart flat or jagged?

The log did not contain a clean, measurable step on that axis. That is missing evidence, not a good result.

Should I tune to a target overshoot percentage?

A target from another quad is not a measurement of yours. Feedforward, stick speed, rates, throttle and saturation all move the peak. Compare against your own logs and let the shape decide which family to inspect.

Where these questions come from

FPV PID Tune: How to read a step response in Blackbox — a clear explanation of the normalised chart and why full-stick snaps overshoot more.
Airframe: Read step response in a Betaflight blackbox log — the estimator limits, accepted windows and the difference between peak and latency.
r/fpv: How does PIDtoolbox's step response tool work? — pilots asking whether the curve is measured or approximated.
r/fpv: Pitch response info — a short flight producing an unreliable chart, and the sample-count answer.
RCGroups: Betaflight PID-Analyzer — the original deconvolution approach and its stated assumptions.
Betaflight: Blackbox logging — what is recorded and why the logging rate matters.

Read your own step response

Easyquadtune aligns the gyro to the setpoint, measures overshoot and the steady-state plateau per axis, and refuses to invent a number when the chart cannot support one. First log is free per browser.

Analyse your log Or watch it work on a demo flight first

More guides: how to read a blackbox log, wobble on hard stops, 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.