Random Twitch Mid Flight

I’ve been having trouble w/ my copter doing a random twitch. Seems to happen about the same time every flight, a little while after I take off. Doesn’t do it again for the rest of the flight. Happens almost every time I fly.

Attached is a pic of it occurring, and so you can see the line number where it occurs.

I graphed a few things, which all looked ok to me. The only odd one was I graphed the ESC RPM’s, and they all go flat right at the time that happens. They’re still reporting RPM’s, but it’s flat there, while most of the flight is a constant fluctuation. Not sure if that’s coincidence or a symptom. You can see on the map, the POS and GPS locations diverge a bit at the time.
@andyp1per said he’d take a look if I got him a log, so pining him. But no worries if you don’t have time to look at this.

If anyone has any ideas, let me know. Really scared me the first few times it happened, but now that I’m used to it, I just ignore it… I would like to figure it out, as I obviously don’t want any issues on my copter. Would hate for that twitch to get bigger and lead to a crash or something.


Thanks for any advice

Hi @wicked1
does anything hitting your FC ?
we can see this in IMU values

Hi, Thanks for the reply.
The first couple times it happened I had seen a hawk in the sky, and thought maybe the hawk tried grabbing my copter.
But, now that it happens almost every flight, I’m sure that isn’t it.

And otherwise, no. Not that I can find. I think the graph is just showing the gyro recording the twitch… I think the twitch basically happens first and then the gyro is showing that. I could be wrong, and am keeping an open mind. But I don’t think anything is physically hitting it or moving.

Yes @wicked1 im not sure about hitting but look forward on the logs, faster movement by yourself have lower imu changes
It was just my theory and could be wrong

1 Like

De-sync? I can’t see anything obviously wrong. The controller is asking for the twitch.

The only thing that makes me doubt that is it always twitches to one side… Never a spin… which is great!! But I’d think if only one motor was affected, it might start spinning, rather than just a pitch or roll movement. Today’s log was a bit of a diagonal twitch, but other times it has gone perfectly on one axis, meaning two motors were affected. Over the weekend it did a big backward twitch, where the nose pitched up, for example. Perfectly even, just the nose went up.

Thanks for looking. I guess I should double check my ESC settings anyway. I might have one of my copters set to auto timing, while I know most of them are hard set… If this happens to be the auto timing one, that’s certainly something to try adjusting.

Does it happen when the GCS is printing “In-Flight mag calibration” or something like that ?

I didn’t notice anything in the OSD while flying, and just looked at the telemetry logs in MP, and don’t see any messages at the time.

I’ve got a very similar issue on my quadrotor. Sometimes it won’t twitch at all, and sometimes it’ll do it a few times. It’s a fwd pitch everytime too. bin file here