Stable lift off of the quadcopter - PID? Other issues?

[drunx]

Hi guys,

I may know partly the answer to my question, but I want to confirm with people who has more experience than I do)

I'm at the final steps of my quadcopter project. NTM 28 motors, Turnigy Plush 30A ESCs, 8x4.5 props. I've balanced the props, assembled everything and now i'm into tuning PID and other settings.

Few things bothers me... I want to know what is the cause exactly so that I can continue working on that:

1) Gyro info. While I have my quad flat horizontal - it shows a 3% pitch forward. I tried as hell to place it as horizontal as only possible, but still, the lowest I saw is 2% pitch. How can I check that for sure? air bubble level looks pretty fine.

2) During PID tuning I've being through many "puzzles" (for me at least). And I want to understand the technics not to worry. So, I want to achieve such settings when I arm the motors, add the throttle to a lifting point, without touche pitch\roll\yaw - and the quad lifts up vertically and stays "more or less" at the same position (of course with very slight deviations) , in general hover at same position (no side wind or anything). I'm not talking about GPS hold position, I'm talking about motors compensating enough and quick to not let a quad drift too much away.

What I have now with different PID settings - is my quad lift first centimeters vertically straight but that starts pitching forward a bit and drifts off...or pitch+roll slightly and drifts away.

Is this purely PID tuning issue? Only PID can affect that kind of behaviour or I should pay attention to something else? And can you recommend a really good guide for tuning PID.

Thanks! I hope you can give me some hint on all that!

[scrat]

First thing you need to do is to flash your ESC with simonk FW for faster motor response and better stability. Then you can tune your PID's.

[drunx]

This is new to me... flashing ESC... how can it be done with Turnigy Plush?

[kopinke]

Hi,

before flashing anything and dig into hardware:
please check your rc values in the multi wii gui and verify that there are at 1500 in the middle position otherwise it could lead also into drifts...

BRDS
kopinke

[scrat]

This is new to me... flashing ESC... how can it be done with Turnigy Plush?

Please read this thread: http://www.rcgroups.com/forums/showthread.php?t=1513678

[drunx]

Thanks guys! I did all the reading and also jumped into flashing my escs:)

Mine are silabs so I flashed blheli on them (on one actually...still have to do the others). Did it via arduino. After I flash all of them - I'll post here about the stability results!:)