Jump at pos/alt hold

[bluuu]

Hello.

This time I had a strange accident while flying in automation. (pos / alt hold).
Environment: temperature of about 15 degrees, wind 5-8 m / s

I was flying normally at an altitude of about 5m. Throttle set at mid-range. Copter suddenly began to rise at full power up.

All course took a while, but I managed to keep a cool head and remembered sequence, and managed to control the situation.

1 All the time on alt / pos hold
2 Throttle to the minimum - copter stopped.
3 Throttle to the middle - again fast construction.
4 Switching to manual - managed to regain control and land.

During the next flight situation is not repeated.

I attach the log.

Can anyone see what it could be?

thr_full.JPG (58.56 KiB) Viewed 12305 times

[LPR]

bluuu

I have had some problems when GPS is being blocked because I'm flying to close buildings. Also if I switch to Alt/Hold before I have a 3D lock.

Larry

[Max]

I can't tell what happened from the logs so far. GPS reception seemed fine, very good accuracy numbers throughout.

-Max

[bn999]

Look at your Z ACC during that time. Vibrations large enough to saturate it. That was the cause.

[bluuu]

LPR: it was very large field, no buildings or other stuff.

Bill: thanks for hint but ... I dont, know what then happens with ACC. Motor and props are balanced (as you see at other parts of log).
Can I tune PIDs or other parameter ? Which one ?

Some times I have some "up and down" bumps in alt hold - mayby it was that ?

EDIT:
One more:
Z is vertical vector, when copter jump up (i have much power) i think it was normal that ACC Z had stronger values.
BUT ....
I have default PIDs except D in Angle tilt lowered to 6200 .... not enough :/

I'll make new post with questions for pecise tuning for my platform, maybe it will be a good tutorial for users

[LPR]

bluuu

Just wondering that your throttle factor is. Do you have very powerful motors?

Larry

[bluuu]

Throttle factor is 0,6 (but still to high yet).

Actualy setup is 4s battery, Hex+, T-Motors 2814-10 (770kV), 12x3.8 APC, weight 2,3kg RTF.
It was made for future chenges like gimbal etc.

When I'll add second LiPo, weight raise to ~2,7-2,8kg.
Gimbal and other stuff 3-3.2kg RTF ...

[JussiH]

[bluuu]

Jussi:
Look once again at my posts.
Motors and props are balanced. Look at logs before and after jump. There are no vibes.
(but I checked it once again).

FC is mounted on dumpers like that:

and 10mm nylon standoffs.

Thanks for hints.

[LPR]

bluuu

A picture of your copter might help as see how your having vibration problems.
Many people don't have problems. How your board is mounted even the diameter of the motor arms can all make a difference.
A few have tried the rubber mounts and I haven't seen anyone have good luck with them.

Larry