QAV Jim

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PID: Newbies May Want to Read This
« on: September 23, 2016, 08:03:41 pm »
This thread is just an FYI to any newbie looking to get PIDs right, or close to right, with the least amount of frustration...

MORAL OF MY MESSAGE:  There is no short cut if you want to do it right.  Take the time to find the UOV and use Optune.  If you have knobs on your transmitter, then it would be totally easier compared to the process I had to use.  In the end, it was worth it.

To begin, I'd like to reference my previous thread I started here on this forum about a low frequency wobble:

https://forum.librepilot.org/index.php?topic=2277.0

I'm new to FPV quad flying but have been flying RC for many, many, many years.  LOS quad flying no problem, however, because the PID settings were not right, I didn't feel connected through the transmitter sticks to the quad and it just wasn't the kind of flying I expected.  FPV flying on rattitude was fun but no way was I gonna try it on rate mode.

I love to research on the net so I thought with research and my flying skills, I'd get my quad's PID settings down by getting numbers and advice from others.  After numerous attempts, I was frustrated and new I had to resort to the CC3D PID calculator (Optune) which requires finding the UOV (unique oscillation value).  I do not own a transmitter with knobs or a laptop so I knew it would be challenge.

SO HERE'S WHAT I DID:  I borrowed a laptop, cleared the garage (not recommended for low-time RC pilots), and started a journey to find the UOV for pitch and roll.

Because the port to the CC3D Flight Controller (FC) is pointed towards the rear of the quad and because the rear of the quad is where I mount the battery, each time I made an adjustment to kP, I had to disconnect and remove the battery in order to connect the FC to the laptop.  I began with default settings flying in rattitude.

So the process was:  Connect the quad to the laptop, increase kP by 10, disconnect from the laptop, mount the battery, connect the battery, hover, land, disconnect the battery, remove the battery, reconnect to the laptop, increase kP by 10, and do it all over again.

It took less than 10 tries to get the roll UOV but the pitch was crazy.  In the end, the roll UOV is .00400 and pitch is .00630. 

I plugged the numbers into Optune and ended up with new PIDs THAT WORK!!!  They are not perfect but I feel much more connected to the quad at the transmitter sticks. 

Flying rate mode is now what I expected and there are no more "wheelies" in the pitch access.  It is so cool flying in rate mode, tilting the thing forward, letting go of pitch control and seeing the quad hold pitch attitude.  Then it's mainly throttle to control altitude.  Nice!

Jim

QC102

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Re: PID: Newbies May Want to Read This
« Reply #1 on: September 26, 2016, 02:00:12 pm »
Because the port to the CC3D Flight Controller (FC) is pointed towards the rear....... 
You can turn the FC around to get access to the USB  from the side of the quad and the reconfigure  by hitting the ATTITUDE TAB  and in the YAW adjust as you can see in the attached image.

QAV Jim

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Re: PID: Newbies May Want to Read This
« Reply #2 on: October 06, 2016, 07:04:10 am »
Nice info.  I just purchased an FrSky X9D and an XSR rx.  When I mount the new rx, I'm gonna do what you suggest here.  The chart is totally useful.  Thanks.

Jim

hwh

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Re: PID: Newbies May Want to Read This
« Reply #3 on: October 06, 2016, 09:06:45 am »
There's a lot of good info where that chart came from in the wiki. https://librepilot.atlassian.net/wiki/display/LPDOC/CC+Attitude+Configuration

Mateusz

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Re: PID: Newbies May Want to Read This
« Reply #4 on: October 06, 2016, 12:01:44 pm »
There are some more options for wireless PID tuning which I recommend


There is also AutoTune that works with Revolution board (automatic tuning works in most cases with few exceptions to very powerful quads). I haven't managed to build such a powerful quad, but we have guys who are able to do that and then TxPID works better for them (Autotune fails).