Gyroscope roll malfunctioning on submarine build

[Zefnoly]

Okay! So i'm working on this new polished version of my microsubmarine. It has 3 rudders in total and 2 water jets on the back. 4 of the rudders are on the side of it. 2 on the front and 2 on the back. Center of mass is between them. I've set them up correctly so I can use the seat to either roll or pitch my sub just fine. the single rudder on the back is used for yaw/left and right steering. And also works fine.

So far my gyroscope is connected to vertical tilt on the water jets to stabilize pitch. The only thing manually controlling direction of pitch is the fins on the side connected to chair only.

I use multiply function and inverters to correctly connect pitch and roll across the 4 fins to effeciently use them for this purpose.

Here is the problem. So far I cant stabilize roll properly (unless I do so manually) it works fine this way but isn't optimal. Whenever I make the roll axis from the chair go through the roll on the gyroscope first I get a weird problem not even my flying vehicles get.

The rudders start to twitch up and down rapidly whenever I reached a stop in roll. As if its trying to keep correcting its roll even if it's corrected. Causing it to rapidly oscilate the roll left to right. The oscilation stays at a balanced phase after it begins and only thing stopping it from happening is doing large turns by yawing. Or jumping out of water.

The oscilation also makes it harder to manually roll with the input from the chair. It doesn't seem to matter what kind of fin I connect it to. I even tried other methods but whenever i'm bellow water it causes oscilation.

It seems to be a problem with the rudders since when I connect them to pitch the same happens. (which is why stabilized pitch is only connected to the water jets but that works fine)

If there is no solution to this I guess I will use the waterjets for stabilized roll as well as they technically can do that alongside making sure pitch is okay... And other kind of rudders kindof break my current design.

[Teamkiller]

Try add more balast - boat usualy looses natural stability underwater. This was the case to many catastrofies IRL (and one of reasons why it is dangerous to sail downwind during storm)

It is better to use PIDs for stabilization. Gyro is not a silver bullet - even some heli designs have same problems (especialy with yaw or when lifting/not lifting heavy load).
You may even need 2 sets of PID parameters for each regime (or gyro fo sailing and PIDs for underwater)

[Zefnoly]

Originally posted by Teamkiller:

Try add more balast - boat usualy looses natural stability underwater. This was the case to many catastrofies IRL (and one of reasons why it is dangerous to sail downwind during storm)

It is better to use PIDs for stabilization. Gyro is not a silver bullet - even some heli designs have same problems (especialy with yaw or when lifting/not lifting heavy load).
You may even need 2 sets of PID parameters for each regime (or gyro fo sailing and PIDs for underwater)

I found a way to somewhat have decent stabilization with gyro but that is through the waterjets... Somehow that works well... The rudders are for manual yaw/pitch/roll while the vertical trim on my two jets is stabilized by the gyro. Gives better results than no gyro.

[Dead]

hi i have the same issue except with my double bladed chinook(https://www.google.com/search?q=chinook&source=lnms&sa=X&ved=0ahUKEwjZpdPHvtjmAhWhoekKHSAPCdcQ_AUIDSgA&biw=1232&bih=517&dpr=1) it randomly rolls whenever i start flying it has plenty of "ballast" with its dual fuel pods but randomly rolls usually crashing into the sea.