Copter shakes during takeoff

I flown my copter few times and everything was ok. Recently during start copter started to shake just over ground. Disarmed cycled power next try same problem but few centimeters above ground was smooth.
I also notices APM Initialize message on my OSD.
I don’t see anything in logs apart from shaking. Can someone look into and help me a bit?

“skaking” is a bit of a vague description. is it vibrations due to an unbalanced prop? … or maybe the tuning for the copter is marginal, and it’s setting-up oscillation/s becasue your PID tuning is wrong…?

I have experienced shaking in some frames that have insufficiently rigid centres.
On power up the arms start an oscillation that smooths out once you are in the air out of ground effect.
Is this what is happening?

Fast shaking right to left, it’s not vibrations, it’s visible fast movement of quite high amplitude.
Before that I didn’t have any problems with start and it flies corrctly.

My Y6 had a bad wobble (low Hz and high Hz) twice. Both instances were props. Once was poorly balanced props (my poor attempt) the other was a prop that had the slightest damage from landing in tall grass. Apparently it doesn’t take much off balance to throw it out when spinning 10" props over 10,000 rpm. :slight_smile:

If props are balanced you can have shaking at take off because the axle of your motor is bent, this would explain right to left movement.

Well doen’t look like a problem with motors or props. I did about 20 flights this copter and this problem happened only 3 times.

Have just encountered what you would call shaking while tuning a 1000 size Octo.

The shaking was an oscillation in yaw while the copter was still sitting on the ground and the motors were spinning up for takeoff.

I initially powered down and disarmed, checked everything, and started again and the shake, or oscillation in yaw happened again.
Giving it more power and lifting off and the oscillations were gone.
Does this sound like it.

This happened after I had auto tuned the yaw and the PID were quite high but very nice in flight, and I was started to tune Roll and Pitch, initially manually.
I had lowered the Roll and Pitch to 3.1 from the default 4.5 when I noticed this oscillation on power up.
The copter was also sluggish in the air.
Taking back up to 3.9 and no oscillation was evident.

Is this anything like what you are seeing?

Yes, sounds exactly like my case. I did autotune. Will check PIDs.

did you get success in it. As, I have experienced the same problem. It happened with me once only and i have taken almost 15-16 flights before which was fine.