[Dirk]

Hello everyone,

Brand new here. Never planned on making a user account because with a google search I can usually find solutions to my drone problems. I very much appreciative of the info available here on librepilot. Anyways, have searched far and wide and am frustrated as all get out. I received a replacement cc3d board from getfpv (the first one, channel 1 didn't work and it drifted all over the place) and just recently put it on my zmr250 build. While I was waiting on the replacement I ordered one from RMRC for $12 due to impatience. It flew great, I was so surprised since it was half the price of getfpv. I flew it for a couple of weeks and after a harder than normal crash it started acting real screwy, all motors revved to 100% upside down, even with Tx shut off, wouldn't arm, etc. So I put the new getfpv cc3d replacement on, and it has the drift issue (right and backwards), in ATTITUDE mode of course. In Rate it seems fine. 

I've done all the things I have read to do from the far reaches of the interwebs:
(and yes I did all these things about 10 ft in the air and not right off the ground and with no wind)
1. Rerun the wizard
2. Recalculate while on a level surface
3. Give the cc3d time to calibrate after plugging in.
4. Played with the virtual pitch and roll-this actually helped some, but at times would still favor the original drift. Even after I had over corrected the virtual roll and pitch and it drifited the opposite direction, after pulling back it could creep back into the original drift.
5. I am trying to avoid messing with the tx trim, so my dx5e should be set for stock trim.
6. Same issue in GCS and Librepilot.
7. Looked at the 3d depiction and it isn't slowly rotating and appears level.
8. Check to make sure the board is level in the drone. Screws are tight.
9. Probably something else I have tried but forgot to list here.

Could there be another issue that I have missed? I am very close to just ordering another cc3d from RMRC because I am so tired of this board not working like it should. Not ready to go straight acro yet.

Thanks for your patience,

Dirk

[jbarchuk]

... creep back into the original drift.

Stability doesn't mean doesn't move. No 'wind': The air is a verrrrry fluid medium and is -always- in motion. Up, down, sideways, back and forth, even though you can't feel it.

When you say creep do you mean a few inches per second? That's perfectly normal. The best GPS holds position within a meter, meaning it drifts to the one side of a meter circle, then back to the other side.

[Dirk]

my point of reference are other cc3d boards that I've used in the past that appeared to work 'normally.' It is not standard drift from my limited experience, it will accelerate in the drift to where I have to pull it back or it will crash in a hurry. My past boards have drifted some, but very slowly I guess, you could say a few inches per second like you described. This is much more aggressive, where I have trouble recovering before it crashes if I do not act quickly.

[NicholasDavid]

"Harder than normal crash" I would look for vibrations.  Bent motor shaft or bell. These are actually really hard to spot. Best felt. On a bench test. Feel each arm for vibrations while spun up. No props.

You describe an exact issue I had. I mounted the cc3d on some thick double sided foam. Solved my issue for sure.

Or one of your arms is tweaked out of line with the others(not level with the rest).

[jbarchuk]

.... This is much more aggressive, where I have trouble recovering before it crashes if I do not act quickly.

Yes, that's different. As NicholasDavid said check for vibrations. I have a minor issue with a 355 size quad. It acts a little weird sometimes and I can't seem to tune it exactly at slow speeds. The problems happen mostly in hover but I spend most of the time if fast flight so I don't care much right now.

Where ND said check for vibrations, here's now I did it. With the model on the bench and NO PROPS (which takes out one variable) I picked up each arm just a little holding the arm right next to the motor. I barely cracked the throttle till they spun. At that speed -3- motors produced no vibration (absolute -zero-) and -one- motor did produce minor vibration. Not a shaking but a minor buzz in my fingers. -All- 4 motors produced vibration at about 1/3 throttle or higher, and none were worse than another. I'm sure that it's that one motor that has some problem but whether it's the shaft, bell, mount, bearings, prop adapter, I have no clue. After a while it will get worse and I'll figure it out.

[Dirk]

Thanks guys for the suggestions. I will do the vibration test today.

ND, I thought you would always want to have your board hard connected to your frame for maximum responsiveness? Wouldn't foam or something similar like one of the anti vibration mounts I've seen for fc mess with your accelerometer readings?

[NicholasDavid]

No. I've had mine mounted to foam for about 6 months now. It's never flown better. It still feels all the roll and pitch and yaw moves just not the vibes. The foams not so squishy that the FC wiggles or anything. It's solidly mounted to the frame. Just with foam.

I fly in rate most of the time anyway. No accelerometer active anyway

[Dirk]

Dear newest best friends,

It looks like you guys helped me solve this issue. I felt for vibrations under each motor but didn't notice anything significant. So I wanted to try sticking the fc to some foam as suggested, but I didn't have any. Instead I used the zmr250 camera piece and rubber mounts to mount the cc3d, using zip ties through the holes. I had to mount it upside down because I didn't have many places to connect it to on my pdb. Anyways, recalibrated it in librepilot, set my virtual roll to 180, and flew it a few minutes in a little wind and it was very stable. I attached a pic of it attached.

Thanks for your help!

[Chilledoutuk]

Hi there did you try increasing the Accelerometer filtering on the attitude page?  As this is supposed to help with drift issues when in rate mode.

[NicholasDavid]

You mean attitude mode. Rate mode turns off the accelerometer. Just uses gyros.

[Dirk]

I've always seen it set to 0.10 and have never read anyone changing it. What would you change the 0.10 to? 0.20, 1.1, 10.1? Would be useful to know in the future if it did help in case my new mount solution fails.