Z Axis Vibrations

rickyg32 · June 1, 2021, 9:54pm

That’s interesting. I did try to compare RPM to vibration increase and thought perhaps I had found one. But when looking further what I found was an increase in vibrations with in increase in motion. So the faster the drone moved the higher the vibration.

As for prop tracking. I assume you mean say one tip of the prop is high and the other low sort of thing. If so. not sure how you test that, but I will have a look to see if something stands out.

As for another brand of prop. That’s not a bad idea.
This is what the machine is showing me today
This is Z Axis vibrations against GPS speed. It’s a shocking correlation

Motor 1 RPM against Z Axis Vibrations

Motor 2 RPM against Z Axis Vibrations

Motor 3 RPM agaisnt Z Axis Vibrations

Motor 4 RPM against Z Axis vibrations

I don’t see anything here …but maybe I just can’t see it.

rickyg32 · June 1, 2021, 9:59pm

It’s funny but when i look at teh motor one graph I almost think I see the vibrations going down then the prop speed goes up. But maybe it’s my eyes.

Lawrence_Dennis · June 1, 2021, 11:10pm

Do any of the props look fuzzy as they spin, If you hover at around eye height (be careful) the props should look sharp and thin at the tip, if it looks fuzzy our out of focus at the tip you have tracking issues.

Yes tracking is making sure that one side of the prop tip path plane is the same as its opposite, both tip path planes need to be on the same plane.

Not all carbon fiber props are equal.

Curious, did you do the auto tune and leave it set?

What are your rate roll/pitch/yaw PID’s??

rickyg32 · June 1, 2021, 11:30pm

I have not tried the fuzzy thing lol…but will the next time I go out.
I did the auto tune and have not messed with it since then. However I am planning on another tune of roll as I think the tracking can be better. Also Yaw is a bit off. In general it’s not to bad, but I think can be better. It flies pretty good, much better then when I first built it. I think there is lots of room for improvement.
But these vibes really worry me. I lost a quad due to Vib compensation suddenly kicking it. Cost me a good few bucks to rebuild it. This is a lot more expensive.
I reached out to a friend that sells drone parts to see about a set of really good props. Just waiting on a response. Even if it’s not caused by the props, a better set isn’t a bad thing.

as for pids.
Here is everything
ATC_ACCEL_P_MAX,89861.76
ATC_ACCEL_R_MAX,90854.23
ATC_ACCEL_Y_MAX,19800
ATC_ANG_LIM_TC,1
ATC_ANG_PIT_P,18
ATC_ANG_RLL_P,11.5187
ATC_ANG_YAW_P,4.5
ATC_ANGLE_BOOST,1
ATC_INPUT_TC,0.28
ATC_RAT_PIT_D,0.01644467
ATC_RAT_PIT_FF,0
ATC_RAT_PIT_FLTD,15
ATC_RAT_PIT_FLTE,0
ATC_RAT_PIT_FLTT,15
ATC_RAT_PIT_I,0.252422
ATC_RAT_PIT_IMAX,0.5
ATC_RAT_PIT_P,0.252422
ATC_RAT_RLL_D,0.007671558
ATC_RAT_RLL_FF,0
ATC_RAT_RLL_FLTD,15
ATC_RAT_RLL_FLTE,0
ATC_RAT_RLL_FLTT,15
ATC_RAT_RLL_I,0.1909764
ATC_RAT_RLL_IMAX,0.5
ATC_RAT_RLL_P,0.1909764
ATC_RAT_YAW_D,0
ATC_RAT_YAW_FF,0
ATC_RAT_YAW_FLTD,0
ATC_RAT_YAW_FLTE,2
ATC_RAT_YAW_FLTT,13
ATC_RAT_YAW_I,0.018
ATC_RAT_YAW_IMAX,0.5
ATC_RAT_YAW_P,0.18
ATC_RATE_FF_ENAB,1
ATC_RATE_P_MAX,0
ATC_RATE_R_MAX,0
ATC_RATE_Y_MAX,0
ATC_SLEW_YAW,6000
ATC_THR_MIX_MAN,0.5
ATC_THR_MIX_MAX,0.5
ATC_THR_MIX_MIN,0.1

Lawrence_Dennis · June 2, 2021, 1:38am

I would try the standard Tiger prop, they have treated me the best. I never go with the stock Autotune, Autotune always seems to go for the highest settings it can, which for normal drone work is overkill. Try reducing your PID’s by 10% from auto tune and try a flight. Sometimes too high I and D can cause vibration. Especially on the yaw.

Your eye is really good at seeing the vibration in the prop, fuzzy is a good description for out of track funny enough.

Your PID’s could get rounded down, we don’t need a PID to the 1 millionth decimal point, simple thousands will work fine.

Your I value is a bit high. If the drone is very responsive on the stick I would start to dumb the I down by .005 and try it again.

Sometimes I tune Yaw separate, after Pitch and roll are good.

rickyg32 · June 2, 2021, 11:51am

Hey good morning.
I think before I tweak the pids I will run another tune on the roll.
I have ordered some good props and they will be here in a couple weeks. Then I will give them a test.

I will be getting the machine out in the coming days so will watch for the fuzzy.
I have made a few updates and want to see the results.
IT may be one thing like props or a series of things compounding the problem.
So I hard mounted the PCM the FC rides on.
Hard Mounted the FC.
Will test this …thumbs up or down this weekend.
Then move on to what ever is next.
I have to admit props could be it. One step at a time.

rickyg32 · June 6, 2021, 1:28pm

So I got to the field today.
Tested with hard mounts on the FC and soft on the motors.
Vibrations are worse.
This is today

This is before the fc hard mount and motor mount change.
Also the machine didn’t sound good.

The vibrations are so much worse I will go back to the soft mount on the FC and remove the soft mounts on the motors.
But I will leave the hard mounts for the PCB.
@Lawrence_Dennis
I did do as you suggested, hover at eye level and watch the props to see if they are crisp and I have to say I just saw fuzz. I have new props coming this week, they should be here before the new weekend and so I can give them a try once they are here.

rollys · June 6, 2021, 5:14pm

I’ve used carbon props of all sizes and didn’t have much luck with them with regards to eliminating vibration. An APC, even not perfectly balanced, had less vibration.

I had a similar experience but used the Tarot Suspension Motor Mount awhile back on a CineTank MK2-L. The original hard mounts worked so much better. Consider that the CineTank’s frame has its motor mount “dirty section” has gimbal type rubber dampeners separating it from the electronics clean section where the camera is mounted from.

Good luck.

rickyg32 · June 6, 2021, 5:21pm

APC are they a plastics prop @rolly. Just curious.
I also noted that the soft mounts made the machines Yaw bias way worse so they are going.

rollys · June 6, 2021, 7:10pm

It’s some kind of fiber composite.

rickyg32 · June 6, 2021, 7:48pm

Interesting.
I have some new props coming this week so will give them a try.
I assume these composite props must have some flex to them and so they cause less vibrations.

rickyg32 · June 6, 2021, 8:22pm

OH CRAP.
I just went to pull the soft mounts from the motors and of the 16 screws 14 where loose despite the loctite.

amilcarlucas · June 7, 2021, 8:09am

To softmount the motors you need to use the extra sticky loctite, not the normal one.

bigboy061293 · June 7, 2021, 9:06am

I really want to join this this discussion since I face the same situation: Will speedup cause the vibration?

Mine is 32 inch - Hexa plus and the props are folding type.

rickyg32 · June 7, 2021, 12:29pm

Hey @amilcarlucas
Yes I know I used the red locktite. That stuff is tough yet the screws came loose. Perhaps I didn’t use enough. No matter, they are out now. Also the 2 screws that didn’t come loose, well they snapped off trying to take them out. So had to swap out the motor. Grrrr…oh well my own fault for using aluminum screws. I hate those things.
@bigboy061293 welcome to the conversation.

Quadzilla · June 8, 2021, 9:08pm

I would try the hard mount only as the logic is to remove isolations step by step right? regarding PID normally you start from a vanilla config. My steps are to delete the config and fly the beast, if it is very twitchy back off the Pids using the slider move it right. fly and look for the pid that is the twitching and manually reduce, normal this is the roll. If you have heat in the motors the expansion and contraction will mess with the screws. Most motors now run very cool so you also need to check them.

I also have a idea add one more deck using the stand off screws that would connect to the frame and hard mount the PRP to the Deck only. think foundations of a house and bedrock if you will.

Harald · June 8, 2021, 9:31pm

I have the best results with the sunnysky EOLO props. Significant less vibration.

BR

Harald

rickyg32 · June 8, 2021, 9:33pm

Sunnysky ELO props…not heard of them.

As for PID’s this isn’t a tune issue. The tune is nearly spot on. Roll is a bit off and I will retune it with the new props. This vibration is something else.

Quadzilla · June 8, 2021, 9:41pm

Cool.

what about this?

rickyg32 · June 8, 2021, 9:49pm

Wow you did that fast.
So I think you suggesting mounting the FC on a Carbon fiber plate with out the dampening washers that come with the flight controller. This is very similar to what I had just tried. It’s not shown in this photo as it’s a bit older. But I used 4 standoffs that where direct mount to the frame. I did leave on the vibration o rings that come with the FC as the holes are pretty large and I don’t have a screw that would fit.
But this mount didn’t work. Now I am not suggesting that this is a bad idea, I just think there is something mechanical thats introducing a high level of vibration and I need to find that source. Once I know I can at least take some form of action. But right now I can’t say what it is.
I do know that the changes I made just made things worse not better.
So this weekend I will test good props. I confess the ones I am flying now are cheap and I cant’ say if the prop tips are level.
So this weekend it would be new props.
Back to the soft mount that is in the photo.
Hard mounted PCB.
Hard Mounted motors…not doing that again. I know a better way of doing this, but not goign to try it just yet.