Never-ending crash-rebuild loop

I have a problem and I have no idea what’s wrong. Please help!
My quad is an alien 680 folding H4, 530KV RCTimer motors, 1555 CF blades, 4S 10000mAh battery, HakRC BLHELI_32 35A ESCs with DShot150 protocol, Kakute F7 AIO board (on o-ring mounts) running latest 3.7-dev Arducopter.
In general, the copter flies - gentle moves are fine, hover at around 40% or so but it eventually crashes every single time!
I have PIDs very low, for some reason high PIDs cause oscillations and crash during autotune. Even with low PIDs YAW autotune crashes my quad when it does diagonal tilting (is it even supposed to do that?).
Anyway, if I switch to Position hold OR start doing fast inputs, the quad starts oscillating and goes down.
Here are my logs:
There are 3 sets in there. Last two resulted in crash and the first one I managed to recover and land.
There is also a screenshot of my BLHeli32 settings in there.
Pleasepleaseplease! I have no idea what’s going on!

I’ve had similar issues and when the copter can’t stabilize itself I’ll quickly switch to acro mode and bring it down to analyze logs. I’ll take a look on your logs and see if I find anything. Also, diagonal tilting on yaw autotune? No, I don’t think it should do that. It should just yaw left and right. I have a feeling your problem has to do with your board alignment (not straight enough, or slightly slanted on any axis) / calibration.

Interestingly, it does yaw left and right AND also it does some tilting for some reason.
I did check orientation and did do all calibrations.
I would appreciate if you could have a look at my logs, thanks!


One thing which is not correct in my opinion is the frame type H (frame_type = 3) you used. You should use type X (frame_type = 1). I had an Alien 680 frame and I used type X with a Pixhawk. Be careful if you change the frame type as motor direction changes.

Is there much difference? I mean Alien frame is sorta in-between X and H, and possibly V… Would it really matter that much?

It’s an X-frame. I had a frame similar to that geometry and that’s what worked for me.

Anton, you have to use x-frame and afterwards do autotune. I am sure that will solve your problem. But be aware about changing the motor direction.

If you have toilet bowl when you crash then move your compass away from electronic s

Every time my copters crashed, was a compass problem. So, now, this is the first item of my anti-crash checklist…

I’ll try again. Initially I had it set as X but it was unstable and I switched to H. Will go back and see…

Usually you move compass from motors to avoid interference. My compass is in the middle of the frame.

The motors don’t make interference to the compass but the high voltage spikes from battery or ESC
You have to move away your compass from ESC ,ESC cables

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You can use a small sheet of MuMetal (0.15mm thick) to block all EMI. I don’t know how is your assembly, but I always use an external compass (with GPS) in the top of the electronics stack with a plate of MuMetal 2cm below it to block EMI. Don’t forget to disable the internal compass if you have one. The results are impressive. Take a look of my assembly…

Good luck!

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Thanks for the info.
Kakute F7 does not have onboard compass, so it’s just the one in GPS. I’m not sure it is affected though, as I did not see any “toilet bowling” in my quad’s behavior.

you need to straighten your motors… there’s a heavy bias on motors 1 and 2

Is it based on latest log or previous one?
Latest flight was probably a bit rushed but previous one should have motors straight.

the log in the original post

real easy to check, just look at rcout

Thanks everyone. The quad seems to be flying after I moved the compass on a mast and changed config to X setup.