This is a discussion re the ArduCopter-3.1 AutoTune feature.  A place for people to report successes and failures, ask questions and get answers.

The AutoTune wiki page is here.

 

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I gave in and tried Autotune today with rc7, I had spent a lot of time tuning my quad to fly how I personally like it and it was flying as well as I felt I could expect but I was interested to see what values AT came up with.

Autotune completed in about 4 minutes.

Mine Autotuned
RATE_RLL_P 0.190 0.175
RATE_RLL_I 0.350 0.175
RATE_RLL_D 0.011 0.015
RATE_PIT_P 0.190 0.210
RATE_PIT_I 0.350 0.210
RATE_PIT_D 0.011 0.015
STB_RLL_P 3.5 6
STB_PIT_P 3.5 6


My 2c's:

- I prefer a high I values as to me it feels more locked-in and a little more resistant to disturbance, a personal preference.

- My folding I-quad is a little longer in the fore/aft plane than the left/right plane, accounting for I presume, the variance between the autotuned Roll and Pitch RATE_P values.

- I had tried a higher D value but got some small high frequency oscillations so had settled on 0.011, quad seemed fine with the new values.

- I had chose a much lower STB_x_P value as it makes the quad a lot less nervous to my inputs and much better for any kind of video'ing or FPV, again a personal choice. I have gone back to my values. (A much better choice for beginners too!)

Hi Joe,

Thanks for the feedback. I get a kick everytime I hear about a good tune :)

Hi Graham, 

Thanks for the feedback!!

Autotune optimises Rate P and D then sets Rate I = Rate P. It then sets Stab P to it's maximum value without overshoot. 

I agree that higher I terms are probably the way to go but I am moving forward with the default parameters slowly and only after I do some pretty extensive testing on each step. So I suspect that I will increase the default P to I ratio to 2 in the near future.

The Autotune Stab P value can be thought of as the highest safe value to go to. If you go higher than this you start to get overshoot in some circumstances.

So my general recommendation is to do Autotune then reduce Stab P to suit your flying style and preference. (most people have not developed a preference on Rate I but the same applies here).

Thanks again for the feedback, you (and a few others now) are confirming my own feelings on Rate I.

Hi Randy and Leonard - thanks to you both for your ongoing support and also to the rest of the dedicated developers who devote so much of their time to support when they could be out enjoying flying themselves.

Leonard - I finally got my altitude drift sorted out in Alt hold and Loiter.

I did another compassmot even though no electronics had moved on my frame since my magpie hit. I think it was the new motors that draw a bit more current that brought my compassmot % up. I moved the GPS/Mag up about 50mm and all became sweet - I had tried all sorts up to this point.

I then had my first opportunity to do an auto tune - went extremely well, very impressive.

I now have a very responsive quad that holds well in all modes and a joy to fly.

Well done Leonard for your efforts.

Regards

John (from work)

Thanks to you, Randy and the others involved for all of this, it's really amazing how far ArduCopter has come!

I think it's so important to know how to apply and adapt autotune results to one's own feel and requirements.

The guy flying aggressively with a light 'copter wants a feel completely different from the guy flying slow and lazy with a heavy camera ship. Likewise, a beginner needs a totally different feel to the guy with 1000 flights under his belt.

Hi John,

Great news! I am glad it worked for you!!!

Thanks for the feedback!

The CG is where you can balance the copter on one finger and have it sit flat like when it is hovering. So if you could measure the positions of the props and the CG it may help me work out what is happening.

Hi Stuart,

It is hard to tell from a video but if you do your tune and post the log I can pretty quickly tell you if you have a "wobble" problem.

Good luck :)

Hi Leonard,

OK, I'll get my gimball off and move my battery central to compensate (it counter balances my gimbal) and give it a go when I get chance :)

Stu

I've autotuned my 3.4kg quad a couple of times now, and for general flight the autotuned PIDs make it handle well (after reducing stab p from 8 to 3.2), but I find descending at max rate (1.5m/s) while stationary in alt-hold/loiter is still terrible. It's very bumpy and pretty much ruins any video I'm shooting.

Specs are 2814-11 motors w APC 12x4.5MR props on 4s, on a UAP2 frame.

I've been running autotune without the gimbal (1kg less), and then putting the gimbal back on. I ended up with the following values:

RATE_PIT_P,0.175

RATE_PIT_D,0.015

Where should I start to try and improve the performance during descent?

Here is a tlog from a flight I just made in ~20km/h wind, and has several examples of rough handling during descent.

Attachments:

Hey Glenn,

I only look at flash logs so if you have some of those I will have a look. However, I haven't worked out what causes the decent wobble. For me Autotune improved this a lot.

Sorry mate, this is still a hard one!

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