Muskoka

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Re: "Bounce" coming out of a flip or roll
« Reply #15 on: February 03, 2016, 09:39:07 pm »
Posted a pic of mine above. My buddies is basically the same. I do notice in a pirouette that it will jump a bit when you stop the pirouette, you can hear the motors rev up a bit as well but only for a split second.

And here's my 330. Used Easytune with it and it has no issues. Perhaps Easytune is hit and miss, and sometimes spits out pids that are no good. I find that hard to believe though, because the 250 flies great in all flight modes, if the pids were off, it wouldn't. And the fact it's both our 250's that are flying slightly different pids suggests that it's more than pids causing the issue.

What flight mode are you flying in your video?

« Last Edit: February 03, 2016, 09:48:03 pm by Muskoka »

f5soh

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Re: "Bounce" coming out of a flip or roll
« Reply #16 on: February 03, 2016, 09:48:50 pm »
If your battery is a rectangular, your PID can't be the same on two axis even if frame is perfectly symmetrical.

As an example, take this dog:


Try to rotate around the roll axis and next rotate around the pitch axis (located where is perfectly balanced)

Which axis is more difficult:
-  to rotate when start from 0 velocity ?
-  to stop when full velocity ?


Muskoka

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Re: "Bounce" coming out of a flip or roll
« Reply #17 on: February 03, 2016, 09:51:46 pm »
Our quads are symmetrical, in shape and balance. That dog is far from symmetrical, lol. He/She looks more like a H quad. ;)

And even if there not to the even to the gram, the controller should be more than capable of handling a slight difference.

The fact that my 330 is setup exactly the same as our 250's seems to keep getting overlooked. It's exactly the same as the 250, only a bit bigger, and it does not exhibit the bounce behavior that our 2 250's do. And the pids on the 330 are the exact same for pitch and roll in every flight mode. Symmetry is not the issue, nor is having the same pids for pitch and roll, the 330 is enough proof.

If it works for a 330, it should work for 2 different 250's, I can't stress that "fact" enough.
« Last Edit: February 03, 2016, 10:02:58 pm by Muskoka »

f5soh

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Re: "Bounce" coming out of a flip or roll
« Reply #18 on: February 03, 2016, 09:57:59 pm »
Your battery is symmetrical ?
Can you ignore the battery weight and how is the volume ?
What the ratio battery weight / Quad weight ?

Play with your battery between two fingers, roll axis and pitch axis...

This dog equal your battery, attached to a perfect symmetrical frame.

Muskoka

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Re: "Bounce" coming out of a flip or roll
« Reply #19 on: February 03, 2016, 10:05:21 pm »
Honestly, your argument is moot. The 330 is just a larger 250, setup exactly the same, shaped exactly the same, flown exactly the same (flight modes) and it doesn't have the same issues. That disproves your theory right there that symmetrical quads can't have the same pids for pitch and roll. If that were the case then the 330 would bounce as well, it doesn't.

Regardless, it's bouncing in both directions, pitch and roll, so are you suggesting that Easytune spit out "bad" pids for both axis. There's nothing wrong with the pids, as I've said way too many times. If the pids were off, it wouldn't fly great, end of story.

We've adjusted the Easytune pid values up and down with our pots on our transmitters on the fly only doing flips (one axis) and there isn't anywhere from .002 to .01000 for pitch proportional that they don't both bounce. Yet I did te same on the 330 and it was pretty much fine from the beginning.

Thanks again, but I really don't think we're going to solve anything here. Back to flying.
« Last Edit: February 03, 2016, 10:26:50 pm by Muskoka »

f5soh

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Re: "Bounce" coming out of a flip or roll
« Reply #20 on: February 03, 2016, 10:20:00 pm »
You're just lucky with 350 quad and the 250 quad need to be tuned.
The two quad are not tuned well, first because the PID are bellow the limits (no rebound) and second because too high (rebound)

Nothing more, see and compare videos.

Another approach is the Optune, old method. this consist in finding the UOV on roll and next for Pitch.

Take a look here:

Follow web link from video for calc sheet.

Article here:
https://250drones.wordpress.com/cc3d-tuning-guide-using-optune/

Muskoka

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Re: "Bounce" coming out of a flip or roll
« Reply #21 on: February 03, 2016, 10:33:30 pm »
The 250's were tuned, using Easytune, just like the 330. Guess we won't rely on Easytune anymore. ;) Oh wait, the 330 "is" fine.

I'm done here, this is going no where. We'll just tune everything (pids) manually from here on.

Re: "Bounce" coming out of a flip or roll
« Reply #22 on: February 04, 2016, 03:01:26 am »
It's a PID issue for sure. The bounce. It's a tell. To high P, not enough D. Something. Let's say we have 2 250 quads and 2 330 quads all running the same motors esc and battery's cameras everything. 2 identical 250's and 2 identical 330's. 2 are just bigger. The two that are small and the two that are big will have different PIDs...period. All four will have different PIDs. Guaranteed. Fly in RATE mode, use high rates to get the speedy flips, expo to back off the crazy... And tune it manually from the start. its really not that hard from a template anyway. 

In clean flight the same thing happens in their version of acro+. The reason your quad bounces is your flying in rattitude not just stright rate or acro+. And if that's not good enough. 2 quads, 4 quads no matter how many quads with exact hardware, frames, software will never have the same PID and be perfectly tuned. They will all be different.


now. Fly in rate.... Turn D down a touch. Adjust P where you think it's good. And adjust out the bounce by adding in more D a little at a time.... Maybe yours is just broken... Yeah that's probably it
« Last Edit: February 04, 2016, 03:15:49 am by NicholasDavid »
5" alien 4s 596grams with battery and GoPro FPV
Lantian LT210 4s 604grams with batt and GoPro FPV
GE X220 4s 6" 513grams with batt and HD cam FPV
Homemade acro X copter. 6" 4s - like a warpquad LOS