Looking for assistance with Oscillations and General Config Help

[smartdave (Dave Glover)]

I am Having a little bit of an Issue with Oscillations in a new Quad that I have built. I have tried autotune but that didn’t help a whole lot.

I come from the DJI flight controller world for about 8 years.

I recently bought and built a large Octo and Quad. Both Running CUAV V5 flight controllers.

I am have a very hard time getting my quad to fly as well as my DJI A2 powered one.

Details:

Tarot 650 Frame with longer motor mounts. Total diameter is about 800mm roughly
4s Battery
4006 Motors with 13" props
CUAV V5 Nano
36Amp ESCs running Dshot 600
Flight controller is mounted on a anti-vibration mount (two carbon plates with rubber isolators on all 4 corners

Motors get very hot, almost too hot to touch after only 3-5 mins of stabilized hovering.
I can watch the compass and the flight controller vibrate and I can hear it in the motors.

I have included a link to both bin files (one using default PIDs and one after auto tune) I am also including a link to a video that I took.

I am no expert in examining the logs, so not sure what I am looking at. However if I look at the Vibe values I can see that Z and X have a max of 6 and a mean of 4, but Y is 25 with a mean of 19

Can anyone help me out?

Thanks

Dave

Bin Files
https://1drv.ms/u/s!AplYZe-uqPEBguhAOba8h44gVQLerA?e=qXYKpD

Video of test flight
https://1drv.ms/v/s!AplYZe-uqPEBgupsn40y-rKOU8omsw

[mlebret]

@smartdave

36Amp ESCs running Dshot 600

Dshot 600 is for small props high kv motor. Your RC out change from 1200 to 1900 on all motors during the flight.

Try Dshot 150 or Oneshot 125 if Dshot 150 doesn’t solve the problem. For Oneshot 125, you have to change wiring and remap RC out to default.

When OK with RC out, check roll and pitch PID:

I use plot-drone for quick log exam: https://plot.dron.ee

[mboland (Mike Boland)]

You also have some major Y axis vibrations.
Even though they are not causing clipping and the VIBES data is not too high the raw IMU shows a different story.

[smartdave (Dave Glover)]

Thanks Guys

Mike any idea why Vibe shows issues with X but IMU shows issues with Y?

Any idea what would cause the Y vibration?

[smartdave (Dave Glover)]

I can see the vibration in watching the compass on the mast.

I swear everything was fine when I initially tried flying it before the autotune. Seems like that’s where the vibration came from.

I swapped out the pixhawk 4 mini for a cuav nano. So I know all the settings were reset.

Is it possible the autotune caused damage to one of the motors and now that’s following me around?

[mboland (Mike Boland)]

How balanced are your props?
Is everything on the frame tight and rigid?
Is anything (eg: loose wires) touching the FC?
Improve the vibration damping on the FC
Try another autotune but reduce the aggressiveness to .05

[smartdave (Dave Glover)]

As a matter of fact the thick compass cable is probably smacking the FC as the compass is vibrating. I will fix that today.

Thanks

[smartdave (Dave Glover)]

Yes the pros are balanced and all is tight

[smartdave (Dave Glover)]

Thanks Mike

Any idea why the Vibe shows a high X But the IMU shows Y? Any idea what would cause a high Y vibration?

[mboland (Mike Boland)]

The only thing I noticed about your X is that it is not at Zero.
You could try recalibrating your Accel’s

How is your FC mounted?

Have you tried to AutoTune at a lower setting?

[smartdave (Dave Glover)]

I will get a pic for you later on this afternoon. I was planning on trying the auto tune on .8.

Thanks for your response

[smartdave (Dave Glover)]

I took a short flight today after make the following changes last night

Rerouted Compass lead so it was not resting on the FC
Dropped the ‘d’ value for pitch and roll
Made sure everything was tight and motors were 100% level
Dropped Dshot to 150

This flight was much better, the motors sounded normal, and after about 10 mins of flying the motors were not even warm to the touch.

There was no noticeable vibration in the compass mast nor on the FC

Definitely moving in the right direction.

I got up in the air, started an auto tune then it started getting windy so I had to abort the AT.

Here is how the FC is mounted

Here are the logs from today.
https://1drv.ms/u/s!AplYZe-uqPEBgusNy7aaLsHj5Pmzrg?e=KLwg4a

[mboland (Mike Boland)]

Your roll and pitch is still oscillating.

I would suggest you do an autotune at the lowest setting and slowly work up from there.

Your motors are still pulsing but no where near what they were.

I would say that cable hitting the FC was a major contributor to the vibration which now is much improved.

Have you read the Wiki regarding the connection and setup of Shot ESC’s?

[smartdave (Dave Glover)]

Thanks for all your feedback Mike. It is much appreciated. I am tied up all week at work so won’t be able to touch it until next weekend.

I have read about setting up the dshot ESCs. On the CUAV boards they support Dshot on all ports. So I am still connected to M1-M4

[smartdave (Dave Glover)]

I made some more mounting changes

I went out a bit earlier today and saw quite a bit of vibration in the FC and plate.

I noticed the compass was back to vibrating.

The compass was mounted on a plate on one of the arms. Thinking that this might be part of the problem, I moved the compass to the main plate. I also stripped back about 3 inches of the compass cable insulation as it was quite rigid.

After I did the I took a test flight. The FC appeared to be perfectly stable with zero vibration. The compass also was not shaking. Position hold held the quad almost perfectly, so huge gains there.

I am thinking auto tune was fighting itself the whole time with the vibrations in the FC.

Here are the logs from today’s quick hover.

https://1drv.ms/u/s!AplYZe-uqPEBgusq0UfXEtSnRGL6WQ?e=HOhNtb

@mboland What software are you using to examine my file? I have tried Dronee Plotter and it seems to work quite well.

Thanks as always for the assistance.

Dave

[mboland (Mike Boland)]

There was still a lot of oscillation so I assume you have not done an autotune yet.

I use APMPlanner for all my graph analysis.

[smartdave (Dave Glover)]

@mboland You are correct I have not yet. Time has been very limited and I wanted to work on getting the visible vibrations out of the FC.

So as of now the FC is very stable, as is the compass.

I did hover for about 10 mins in poshold and it was very stable in both altitude and horizontal position.

Thanks for all your help

I will report back after the coming weekend

Dave

[smartdave (Dave Glover)]

@mboland

APMPlanner

Out of curiosity, what should a good graph look like?

[OldGazer]

That really looks like a Hexacopter frame to me, and if you are using it as a quad, the motors are going to be in the WRONG places when you unfold the arms. This is going to wreak havoc with the PID controllers.

Exactly what Tarot frame is that?

[smartdave (Dave Glover)]

It’s an Ironman 650 quad. I have over 10 years of flying drones from little 250mm all the way to 1300mm octo’s. But this is the first time I am not using a DJI FC.

The motors do spin the proper direction so no problems there. I think after removing the vibrations, the last thing I need to do is the auto tune as @mboland has been saying. I just haven’t had the time