Hoverfly Slight shudders in Manual mode but not AL?

[jcmonty]

Hello all,

I am noticing some slight shuddering that leads to slightly shaky video when i am flying in manual mode that seems to go away when I am in AL. Could this be due to a low or high gain setting? I would normally blame this sort of shaky on unbalanced props or over damped isolation, but since it looks like AL does not exhibit this behavior, I am wondering if I am not optimally tuned yet.

My specs:
Y6, Avrotos, 12x3.8 SF top, 13x6.5 bottom, 3.6 kg weight, 4S, HF Pro w/4.3.860 and gains of 55% (both AL and manual)

If it helps, i can upload my unedited video. Just will take a while.

Thanks,

 

[Earl E Adobtr]

I've experienced this. I have best luck using manual mode gain as determinant then, rote, set Al against the manual setting. I never even try to set gain in AL. Just a routine I have found reduces headaches. Also, even minor elevation (350 ft) changes will necessitate gain readjustment.

 

[jcmonty]

I think what you described is what I already do. I set my main gain and then matched Al to it on my EPA. I may try increasing the gain today. Ths strange thing is that Al didn't have the shudders and manual did. I would think it would be opposite or both rather than just manual

 

[Earl E Adobtr]

JC, You would be lowering manual mode gain until you obtain absolute smooth video then lowering it about 2 points further to account for "the gremlins". Then set AL gain same as manual. Raising gain would most likely increase the shudders.

 

[jcmonty]

K I will try that tonight. I also will change out some props that may be unbalanced. Again I would think that's a problem that would see up in any mode

its very platform dependent but do my gains look high? I have them the same on my radio but the y differ in the seep client.

 

[jcmonty]

Changed to a large manual tilt camera mount + my T2i and the shudders are back on the camera. Since i have the mount isolated, the shudders are noticeable because the camera+mount acts as a pendulum, motion being amplified by these shudders. I am going to lower my gains to see if that helps. Once again, Auto-level seems smoother.

Does the HF Pro cope well with negative z-CoGs very well? I would assume so since the market is aimed towards AP/AV which usually requires a large mass hanging below the copter.

 

[Earl E Adobtr]

I experienced this exact same problem when I added a camera mount that had rather bouncy suspension. I ended up jamming some foam in to reduce the bounciness which allowed me to increase the gain somewhat. Then, when I later swapped out motors and esc's for better ones, I was able to almost double the gain and at the same time get rid of the foam. So from this I concluded that the lousy motor esc combo exacerbated the problem with the bouncy camera mount but the mount was not the real problem. Also, keep in mind that any time you increase weight without lowering gain, you will get the shudders.

CG relates more to control than to shudders.

 

[jcmonty]

I don't think my motors/escs are the issues since I run Avrotos with DYS simonk flashed ESCs. I will try lowering the gain tonight to see any differences. Its still strange to me that AL seems to get rid of the shudders and I have the EPA for the gains matched. I will also try stiffening up the mount a bit. My weight increase by about 200-300 grams.. so not too much.

To me, I would think that increasing weight would want an increase in gains. Since you are adding weight to the system, the motors need to output more thrust in order to exert control or movement. The gain would increase in order to account for the higher demand. This is obviously incorrect thinking, and I would love to hear the real explanation.

 

[Aerovideo]

This is an interesting thread, thanks for the informative posts. I'm finding with my newest quads that hovering around is fine as is slow flying. But as soon as I put some punch into the throttle I get what I think you guys are describing as shudders. I've got my gain REALLY low on my new woody quad and am afraid to go much lower.

 

[jcmonty]

My gains are currently at 35/35 (EPA percentage - not sure what they are in the setup client). It flies pretty well and the shudders are much less, but I have noticed that in descent it is a bit more rough. I can here the motors changing RPMs rapidly and sometimes a get uncommanded yawing in faster descents. This was not present before with my gains higher.

 

[Aerovideo]

In my Dx8 the gains are set at 15 when I use a 4s battery but I can get them up to 30 when on a 3s battery but it doesn't have the same punch as the 4s.