Large servo throw and autotune

On a quite light and overpowered plane with large servo throw (maximum mechanical), the default autotune is really hard to fly, because every turn is very abrupt, and >80% rate for tuning is a very big turn, that is hard to not crash the plane. (but I can fly it in the manual mode, and of course I double checked every surface/rc move in manual and FBW)

If I lower the AUTOTUNE_LEVEL, will it be easier to tune the plane ? Any other advices ?

The goal is to be able to fight against strong wind in stabilized mode.

Thank you

Great question! I recommend that in addition to lowering AUTOTUNE_LEVEL, that you also manually lower the controller gains before autotuning.

As I understand it, the AUTOTUNE_LEVEL only adjusts how ‘quickly the autotune learns’ the control gains. The theory here is that on a low level (1 or 2) the autotune makes very small changes, so it will take a long time to tune well… but on a high level (8 or 9) the autotune will make large changes, which massively risks the chance of over-doing it, and making the plane unflyable. Depending on your confidence as a pilot, I recommend that you set the autotune level between 3 and 6. The lower that you set it, the longer you’ll have to fly in autotune mode.

The other thing I recommend is to drastically lower the P, I, and D gains. I don’t remember their default values… but try putting all of them at 1/2 or even 1/10th of the default value, and do a ground-test of the control surfaces in FBWA mode. The goal is to put them so low that the plane is “sluggish” when you begin tuning, and that the autotune gradually raises them to turn more acceptably.

Does that help? Feel free to post logs or more questions!

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Thank you for your complete answer :slight_smile:

When starting AUTOTUNE it first set new PID values depending of the AUTOTUNE level, so how can I set a lower default PID value that will not be replaced by AUTOTUNE ?

Oh, I did not know that. I regret that I don’t know the answer… does someone else?