Poor autotune performance in 5 inch quad

hello. I have several tuning session on 5’’ quad
autotune roll axis

after this tune session everything OK. Quad fly well.
i change battery, change tune axis to pitch and try autotune in poshold

After autotune success i land it. Try to takeoff in stab and i can’t control it. It became totally uncontrollably on pitch axis. I found autotune set Stab P extremely small. Probably because i autotune it in poshold mode. So i restore pitch pids and try autotune again.

Now i change tune axis to pitch + yaw and autotune in althold mode. And again after autotune it became uncontrollably. So i emergency land it via motor stop feature. But when i see PIDS after autotune and they was normal. I manually lowered it a bit and try another attempt.

After this autotune session everything ok. I try control it in stab mode, and it fly good. I don’t understand why previous attempt was bad.
Also i see Autotune reached limit on pitch and roll axis. How can i fix it?

I don’t think the last log corresponds to a good tune.

Especially the pitch axis still bad.
Did you follow the tuning wiki?

oh i send bad log twice

here good autotune

In our case, we always do autotune in Alt-hold flight mode.

Likely able to see notification messages and results of the tune under Mission Planner using a telemetry radio.

autotune pitch+yaw-bad.bin

was made in althold

Have you done the MOT_THST_HOVER? a good value should be less than 0.25.

Remember to double-check the initial parameters set.

Check out the spreadsheet as well.

i set MOT_THST_HOVER 0.11
Throttle Accel P 0.11
Throttle Accel I 0.22
and also initial parameters for 5inch quad

Oh, we usually don’t set MOT_THST_HOVER, we use default and fly and let the copter FCU set it (MOT_HOVER_LEARN).

We never change these two values before Throttle Accel P 0.11
Throttle Accel I 0.22.

MOT_HOVER_LEARN can set only 0.125. But my quad hovering an 11% throttle from log file


oh okay, PSC_ACCZ_x we change. hmm, looks like you have used a set of motors that are overpowered. You can consider trying MOT_HOVER_LEARN to see it gives you 0.11.

Double check on the MOT_THST_EXPO value too, should be 0.55. more accurate you can use the motor spreadsheet to calibrate if you have the motor data.

below are the initial parameters calculator will change from the default base on propeller size.


Your hntch frequency is too high, leave it at the default of 80/40

I’m not sure whether this is affecting the tune - as you say the pitch tune is awful, but it’s not clear to me why this is.

You had high vibrations on the Y (pitch) axis. That may be a cause of your problem. Note the wrong calculation of the mean value in the legend. I wonder why this happens.

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