KK2 Board Tuning: Help Please

[T-Ro]

Well, my quadcopter is complete! I have learned how to fly on a Nano QX, now know how to build a quad, but I am having trouble learning how to tune my quad by myself.

I have watched many different videos over and over about P&I settings, what they do, and how to tune your quad. But I am still having trouble and I am sure that there is something that I am missing that will make the problem go away... but that is where the lovely community comes in.

My Set-up

• Electro-Hub
• Turnegy 30A Plush
• 1000 kV Motors
• 10x4.5 Props (Balanced)
• KK2 Board (Self-Leveling off, V1.17S Pro [can't update with my USB ASP])
• Spektrum 6-channel RX

Strange Things Are Happening
So, in my personal understand of P&I gains on the control board, the higher the settings, the greater the CB will want to correct shifts on the platform. You want to raise the P gains until you start to get an also oscillation, back it back down a hair and then you get your P gain settings. Then you move to your I gains. You simply want to make sure you platform isn't self leveling once you put it into an attitude.

But here is the strange thing: to keep my platform stable, I have a super low P gain settings (talking about 15).

If I lower the P gains into the single digits, I violent get oscillation. If I go above 25, I get violent oscillation. So I am stuck at like 15 or so for my P gains.

The oscillation that I get is very violent and enough to have it pretty much be flipping over. But if I hit the 15 or so values on my P gains, I can hover and stay pretty much still. But now the problem is that I can't actually fly patterns, because when I begin to move around oscillations pick up and will eventually make the platform erratic and uncontrollable.

These P gain values are just so low I know that I am missing something (knowing most people have their values around 60-100). But then again, I am new to learning how to tune my KK board. I simply have been messing around with my settings trying to find a sweet spot... the settings below are the best that I can do... but it doesn't allow me to do more than hover without oscillations.

Attached below are some pictures of my KK board, hopefully someone can spot something that looks off and I can learn a little bit more!

Self Leveling Settings (I turn off my self-leveling)



Profiles



P&I Settings For Yaw



P&I Settings for Aileron & Pitch (Linked)



Mode Settings



Version

 

[Craftydan]

T-Ro, Welcome to the forum.

Something to keep in mind with PI or PID controller is that they rely on feedback and response -- the controller does something, sees how it changes the attitude, decides what it does next (based on the gains), and does the next something . . . all with the goal of meeting your command.

If the gains are exceptionally low, that means there's a lot of slop (inherent error) or noise in the loop -- go too much higher and you either control beyond what your speed controllers can keep up with, or you amplify the noise coming in.

. . . so how do you fix that?

- Reduce the noise: Vibration -- balance your props, balance your motors, vibration isolate your control board

- Tighten your ESC response -- re-flash with a Multirotor ROM (or replace them with ESCs that are pre-flashed.

- Improve the control loops (Have I mentioned the stock KK2.x ROMs are garbage? no? they are.). (Edit: NM. Steveis 1.17 should be good on this account)

Hit those three points, and not only will your gains increase, you'll get a MUCH snappier craft.

 

[T-Ro]

Thanks for the tips Craftydan!

I pretty much have tried all of those things. Granted that I don't know how to program/flash my ESC's.

But I have balanced my props, motors and I have isolated my control board (CB is foam taped a 1/4" foam square, which is foam taped to a plywood square, which again is foam taped to the platform). If the KK2 V1.17 is good, then how would I proceed forward with flashing my ESC's?

I am trying to find some videos to show me, but could you point me in a direction to see what I can do?

 

[HarleyRev]

increase the P limit to 80 to 100 . Turn auto off, take out all I gain. Start the P gain @ 60 (with P limit 80 to 100 ) , raise it up and look for the oscillations you talk about. Keep increasing until you see it twitch , then back it down 10.

I just learned this for the I gain, start it out same as you P gain setting. Put I limit around half of your P limit. When the I gain is too high it will "search" around, never quite stopping in hover. You will always be moving the sticks chasing it to get it back to one spot. When it starts searching, back down the I gain.

Try this after you follow Dans suggestions.

Good luck ! let us know what happens.

With auto level off, when you give it a stick input, the quad will remain at that angle until you counter it. With auto level on quad will return to level when releasing the stick.

Then the setting for P&I for auto level will be around half of normal settings.

Does your KK have the ACC and gyro bubble ? if so check those out to ensure the bubble is at center spot after ACC calibration. If not the quad will behave in very strange ways.

 

[HarleyRev]

http://www.rcgroups.com/forums/showthread.php?t=1587028 forum thread for your ESC

 

[T-Ro]

Well darn.

Looks like I will just go and buy some new ESC's... any recommendations for multirotor ESC's?

I just programmed the throttle range for my ESC's... not sure if that will help with oscillations, but I will take a guess and say that they will not.

@HarleyRev
I am simply afraid to put the P gains that high... the first time I set up my quad, it literally just flipped and smashed into the ground. I can try to work my way up slowly to those values. But I have programmed the ACC and the gyro bubbles are on spot.
I already know now to fly a dialed in quad, so I am really not interested in flying with an auto-level... but I know that the I values will change the attitude of the quad after giving an input and letting off the stick.

I could try and create a programming pin for the ESC's, but looking through those threads it looks like I would need to know about the ESC chips and know which points are what to program it correctly. Once again another learning curve... one that I will probably just avoid for the moment.

 

[Ocean]

I had stock turnigy plushes on my old tricopter and also had exceptionally low gains, I ended up ditching the thing. If you can reflash to BLHeli or SimonK then that is great and hopefully might fix your issues. Some others to look at are RotorGeeks or Hobbyking Afros, they run BLHeli and SimonK stock respectively. (RotorGeeks also have the ability of doing Oneshot125 right out the box, but don't worry about this feature yet)

BLHeli and SimonK are both multirotor optimised firmwares for ESCs, they make a TON of difference to regular plane ESCs.

 

[HarleyRev]

i dont think the quad flipping has anything to do with the gains set too high. Too high P gain only makes the quad more sensitive to the stick.

I dont think I gain has anything to do with changing the attitude of the quad, it corrects error over time, too high I gain will only make the quad search or hunt around in space.

watch this video, it helped me more than all videos I watched on the KK tuning https://www.youtube.com/watch?v=00PoZ5Xza8k

Quad flipping usually has to do with motor/esc being hooked up to the wrong port on the kk board or wrong prop on a motor.

Check your motors/esc for correct placement on the kk board. When you take out I gain and put the P gain to 80, pop it up about 3 feet high, it will hover. If the P gain is too high it will oscillate, there should not be any violent reactions from the P gain at that level.

I previously had my quad P and I limits set on 20 , after watching this video I changed them to 80 and it made it way more stable.

 

[T-Ro]

*Sigh*

I have done this already. Motor layout is correct, motor spin in the right direction, props are balanced as well as the motors. I have calibrated my ACC and my ESC's. I have isolated the control board from any remaining vibrations as well.

Also, I have already walked through this video you posted with my KK set up... I am still learning how to tune my PID settings.

I can try and set my P gains higher... but the oscillations are very violent so much so that it will flip over.


I have some other ESC's that might have been pre-flashed with SimonK, so I will try first to set my gains up to the 60-80 range as you all have been suggesting. I am already confident it will be very violent, and I will simply switch the ESC's after I try this test.

Will report back in a couple of days on my progress.

 

[Craftydan]

Harley,

It's not an insta-flip he's fighting -- if he ever has stable flight, even if it's horrible, he's got the board and motors laid out correctly.

I'm also not sure the "hunt" issue is quite right -- An airframe will oscillate at a much lower frequency (and possibly quite violently), but "I" gain actually damps position errors -- that's it's whole place in life. Typically I'll tune P first with no "I", then bump up "I" until it holds angle reliably -- having "I" any higher than this will actually dampen P's effect, even if you haven't gone high enough to see the low frequency oscialtions from "I" -- RoT: push P as high as you an get it, set "I" as low as it can be and not drift . . . D is a problem for another day

T-Ro,

The plush 30's would require a flash to BLHeli, since the plush series has switched over to SiLabs chips a while back. If you want to take this route, it's not particularly simple, but if you've got an Arduino board it's doable -- the software tool you need is BLHeliSuite:

http://www.helifreak.com/blog.php?b=2162

The software should be able to step you through setting up the board and flashing the ESC, but be prepared for a lot of reading. Looks like it has it's own rom version, so pick "TURNIGY_PLUSH_NFET_30A_[version number].HEX".

As far as other options, the Afro series isn't bad -- a bit pricy but fine -- and the F-30A's over at HK are good If you want to try the simonK flash -- you'll need to build a wire adaptor to grab the programming pads, but the F-30A/F-20A has them on the board edge, all in a line. should be able to plug into your USBASP and setup the kkmulticopter flash tool to push the ROM over to the ESC.

 

[T-Ro]

Two things that I have learned:

For my Turnigy Plush, I reprogramed them using my RX and changed the timing on them to "HIGH" which helped out a little bit. I was able to get my P-gains up to about 30 or so without the oscillations. But eventually while trying to fly a little bit of patterns the oscillations came back and thankfully I was able to land safely.

I traded out my Turnigy with some SimonK pre-flashed 20A ESC's and my first test was much better. I sadly can't find my voltage checker, so I stopped early on my testing and tuning to not over-stress my battery... but my P-gains were up to 70 and I could begin to notice the quick oscillations from the flight control board. I know that I just need to keep moving up the P-gain till I get that wobble, tone it back a bit and then work on my I-gains.


Lesson Learned: Have quad programed ESC's for quads.

Thanks for all of the help everyone!

 

[T-Ro]

Good news!

After changing out the ESC's with pre-flashed SimonK's and charging up some batteries I went out to tune my quad.

After a couple of batteries of hovering and tuning, I have a functioning quad! I don't fully remember, but I think that my P gains were around 90 or 80. Much better than 15 a couple of weeks ago.

But I still have one more question:
When I am going through a sloping turn (aileron and rudder with slight back elevator) the quad accelerates and gains elevation. It is kind of strange because normally my Nano QX will lose elevation when going through a sloping turn... but this quad actually revs up and gains elevation through turns. Is this because of the gains?

It really isn't a big deal because the flight characteristics of this just means that I can pull back the throttle through the turns. These characteristics are not threatening to the platform just something I am not use to.

If anyone has some input, that would be awesome!