New SAS Acts Very Weird

[waterlubber]

With the addition of the new SAS, a lot of my probes have been acting quite odd lately. There seems to be really odd oscillations, and they stop whenever I turn off the reaction wheels.

Is this intentional, is the SAS acting like the old one?

I have a small probe consisting of an flat OKTO and a small .65 reaction wheel, as well as a rockomax mini engine thing. It's perfectly balanced according to RCS build aid.

Anyone know the cause of this?

Playing in sandbox.

The SAS doesn't seem to be moving the controls at all, and the trim was set very strangely when I first loaded the craft.

My joystick was plugged in, but the trim is still very weird after I unplugged the joystick.

Not sure where this belongs.

Edited December 31, 2014 by waterlubber

[DSM20T]

Are you using remote tech by chance?

[LordFerret]

I'm playing a Science_sandbox game, and yes, I've noticed the same too. It tends to show up on my rockets while in the upper atmosphere just before going for orbit. Don't know why. Could be related to an imbalance with my payload though, several tons worth. Another thing I've noticed is, when using the Navball presets, they over-compensate and burn a lot of RCS. I do better job manually. However, I do find the one setting handy (retrograde) when dropping landers to the surface.

[waterlubber]

Nope. Seems very weird, the inputs in the lower left look like trim, but whenever I transfer focus to another window (e.g alt+tab) they seem to snap back correctly, or when I mouseover the debug menu. This makes it seem like control input. They're about halfway, and roll and yaw are the stuck ones.

[sal_vager]

No it's not intentional, if you have too much reaction wheel torque for the mass of your craft it'll jitter, and of course a probe tends to be lighter than a pod, add a few inline reaction wheels and you have a problem.

The SAS code needs tuning, that's all, it should be fixed for 0.91 but until then I recommend Regex's PID tuner.

[InF3RNo]

Yes I felt something weird while going out from atmosphere to space.

[waterlubber]

Nope. Seems very weird, the inputs in the lower left look like trim, but whenever I transfer focus to another window (e.g alt+tab) they seem to snap back correctly, or when I mouseover the debug menu. This makes it seem like control input. They're about halfway, and roll and yaw are the stuck ones.

I made a video showcasing the issue:

[kujuman]

As Sal_vager said, it's most likely too much torque compared to vehicle mass.

As for the weird trim, I find that for me trim will just cause a roll rather than oscillation when the SAS is engaged. I hope you can solve that issue.

[waterlubber]

I rebooted KSP with the joystick unplugged and it worked...the moral of the story is;

do not boot with a joystick plugged in

[sal_vager]

I rebooted KSP with the joystick unplugged and it worked...the moral of the story is;

do not boot with a joystick plugged in

Heh, I forget about this, but seriously, stick a load of reaction wheels on a small craft and you'll see what I mean about the SAS.

[waterlubber]

Heh, I forget about this, but seriously, stick a load of reaction wheels on a small craft and you'll see what I mean about the SAS.

I have.

I also make them slightly unbalanced.

And I physics accelerate too, because that adds to the fun!

(The worst is when your craft shakes itself to bits without SAS or any input whenever you don't put it on rails for 3 seconds or more. I hate that.