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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Hello,

After finaly completing my hexacopter build and after some time familiarising myself with apm and general multi
rotor flying, i wanted to give autotune a try. Unfortunalty didnt go well on the first try. i'l attach video to
show the problem more clearly, but in general autotune seems bit too violent on tuning. As seen in video at one point autotune almost manages to crash the hexa, but quick exit from autotune to loiter saved the day. Since i havent managed to succesfully run autotune i am using default pid settings atm and loiter is actualy pretty stable with them. Only when i try to fly bit more higer and with wind it kinda goes crasy. Starts jumping up and down violently, prolly baro problem. But still wanted to be able to complete autotune. :)

Hope someone has bit time to read this wall of text.

Video of problem: http://youtu.be/TMHbSqzX_Vg

Specs:
Frame: X-CAM CF6-Mini Collapsible Hex-Copter Frame (Full Carbon) (780mm)     
Controller: APM 2.6 (3.1.2)
Gps: 3DR uBlox GPS with Compass Kit
Esc: Turnigy Multistar 30 Amp
Motors: Turnigy Multistar 4822-570Kv 22Pole
Props: Carbon Fiber Propellers 12x3.8
Battery(x2): Turnigy nano-tech 5000mah 4S 45~90C

Edit: Just incase uploaded logs to different place also.

http://speedy.sh/u8QXp/Autotune-logs.rar

Attachments:

Hi Egert,

Sorry but I can't download your logs for some reason.

What I suspect is happening is your default tune is too high and the copter is not recovering well from the autotune test.

I would suggest you drop your roll and pitch rate P I terms by 50% and try again.

Let us know how you go.

Also, make sure you are using the latest release as it has an important bug fix.

Hi, I'm reading all this discusion about the autotune. I find it very interesting.

I hope to do some tries on next weekend, meanwhile I'm thinking in the following idea.

As I don't want to wait 7 or 8 minutes to get the first results, perhaps I would change this parameters by the double

#define AUTO_TUNE_RD_STEP                // minimum increment when increasing/decreasing Rate D term #define AUTO_TUNE_RP_STEP                 // minimum increment when increasing/decreasing Rate P term #define AUTO_TUNE_SP_STEP                  // minimum increment when increasing/decreasing Stab P term

In that way I will get less accuracy PID values, but in the half of time.

Am I Right?

Thank you very much for reading. Best Regards.

 

Hi Facundo, that is correct.

That should speed up your tune by a factor of 2. Let us know how you go.

Why would you want to reduce the accuracy of the auto-tune?? You don't want to wait 7 minutes for something that you spent this much time and money on?

I'l try to upload without compressing it, hope it works now.

Attachments:

Thanks both of you for the answers.

I've read the experience of others and I'm start to think that maybe It would be nice to approach quick to a value near perfect and then if you want, you could make another try changing the range of values of P and D to try closer this first pass value, but with a smaller step, getting even more accuracy.

My opinion is that perhaps that is not necesary because i read someone here who ran four the test and got similars values but with a difference of 0.01 in the KP

On the other hand I think it is a good option for those who don't have enough autonomy.  

 

 

 

Dear Developers,

I've had a very strange experience with my quad. It is flyable in Stabilize and Altitude hold as recommended but my AutoTune flight resulted in the craft becoming erratic and eventually going ape after only a few seconds. I tried to disengage AutoTune but at that point the copter was flipping and rolling and it was a battle to get it under control. It crashed, ironically in the grave yard. Managed to get it back together again and then yesterday I flew it again and after engaging loiter it just flipped over and crashed. Could anyone take a look at my logs for the Autotune which I have attached and tell me what they think the problem is? The logs and report from yesterdays flight can be found here: http://diydrones.com/group/arducopterusergroup/forum/topics/fw3-1-3...

Copter Specs:

APM 2.6: FW 3.1.3

Frame Type: Quad (X)

Motors: T-motor 4008-18 380kV

Props: APC SlowFly 14x4.7

ESC: Castle Creations Pheonix Edge Lite 50 Amp

LiPo: 6s 6000mAH 30C

Attachments:

Hi,  I'm a little stuck with the auto tune.  I get roll corrections for about 6 minutes, then my low voltage alarm goes off and I have to land.  How can I get a good auto tune with 7 minute flight times?  Is there a way to split the roll and pitch functions, or make it faster?  Thanks!

-Nate

I have a similar problem..  

I can only stay aloft for about 12 minutes before I have to start worrying about the battery.    I just did an autotune today for the fist time (I had zero wind).  My 3DR Hex behaved just like in the video at the beginning of this thread.  Alt hold works very well on my Hex and it only took minimal correction to keep it in one place.

But..  After 12 minutes, it was still doing the fore/aft pitching.  I had to land.

How long is this supposed to take?

Five minutes for me.  2-1/2 For roll then 2-1/2 for pitch.

If you post the logs here I might be able to give you some starting pid values that get you there faster.

The time autotune takes depends on how calm the conditions are and how well setup your copter is for autotune. By how well setup I am referring to things like movement in the arms, battery, or gimbal and how well chosen the motor/prop/battery is for the frame and weight.

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