Discussions

Hello Everybody! I've been stalking this forum for some time as it's helped me immensely get to where I am now. And I very much appreciate all the help that everybody has provided.

Given that I now have a few flights under my belt, I had a couple question regarding PID tuning so that I can really dial in my quad. First, I'll provide some good background as to what I've been up to and how I got here so you understand what I'm looking at.

I've always been infatuated with RC aircraft, just never had the wherewithal to make the jump from land to sky. That is until I saw some of Juz's videos on YouTube that I made it work! 

So I went out on a fact gathering quest to find out as much as I could in a relatively short amount of time, and utilized a bunch of different resources. In the end, I pulled the trigger on the build below for the following reasons:

a. Knew that I wanted a fully-capable autopilot with great support so when I run into issues like this I have help (:

b. Saw what Juz and other people were doing with this innovative frame 

c. Knew that I want some serious acrobatic ability

d. Knew that I want some really crisp video without any wobbles

e. Thought it was a great place to start - not too big, yet would be stable enough for me to handle as a beginner

Thus, I started amassing components and wound up with the following:

-QAV400 frame from FPVManual.com

-Tiger Motors MT-2212-13

-Tiger Motors 18amp ESC

-ArduCopter APM 2.5 / GPS / Telemetry

-Futaba T8FG Super

-HobbyKing NanoTech 4s 3300mah 

-Started with the Graupner 8" props, but after a few incidents I couldn't source them anymore (and probably a good thing b/c I've gone through a few!), so now I'm onto a set of Nylon GemFam 8"

In addition, I just grabbed up some FPV gear but that's for another story. For now I'm sticking to LOS until I've not only honed in the PID tuning, but also my flights kills for obvious reasons.

So, long story shorter, after I got everything together, I soon realized that the standard PID settings in the APM were way overkill for this frame. As soon as it would take off, it would wobble uncontrollably and I was forced to kill power, sending the frame a couple feet to the ground. A few minor components later, we're back in action.

Now, I've verified all the rudimentary items like:

a. That the motors are all square / true

b. That the props are all in good order (yet I'll admit, seem to be somewhat flimsy)

c. That the CG is nearly perfect on both axis

So, that brings me to where I am with PID tuning... I've used DaveC's PID tuning guide, and I'll say that it got me pretty far, but I feel like there's something major that I'm missing here. Aside from tuning in Acro mode with the quad attached to a frame / my hand, I fly 100% in Stabilization mode to try and get this thing buttery

STAB_P: 2.155

STAB_I: 0.1

STAB_D: 8.0

RATE_P: 0.1250

RATE_I: 0.7000

RATE_D: .0050

The issue: While the copter is nearly perfectly stable in horizontal flight / just sitting there, once I start to pull some "G's", it gets fairly fluttery with some serious oscillations, but is always fully capable of pulling out of it. 

With some in-flight tuning, I was able to get the RATE_P upwards of .1520, but once I landed and took off again, it went right back to that uncontrollable wobbles forcing me to cut throttle or it was going to wind up the next town over.

Here's a video from one of my first Recorded Flights that really exemplifies the issues that I'm having... It's very apparent both on take-off and when I cruise around corners.

Since this IS the home of ArduCopter, is anybody else flying this frame? What PIDs are you guys using? I've tried my darndest and can't find anybody else helping with PID info. All I'm looking for is some guidance on where I should explore next with this issue. Higher RATE_P while lowering STAB_P? 

Thanks a ton guys, certainly look forward to posting a ton of videos in the future to help support the community!

Regards,

-Ryan