strange control drift.

[Netskimmer]

Hi all,

I've been away for some time, but getting back in to KSP. I was noticing that my rockets seems more difficult to control that I remember. I assumed that I was simply rusty, but once I got into orbit I realized that I'm getting a strange drift.

In the vacuum of space with just my command pod awaiting reentry, the pod rotates diagonally across the nave ball. This happens both with and without SAS. I assumed it was a calibration issue with my joystick so I tested it and it seems to be working properly. I don't think there is a way to calibrate within KSP, and I am afraid to unplug the joystick and use keyboard controls because the last time I did that, KSP wiped out my key bindings for it.

Has anyone else had this happen?

[RidingTheFlow]

Is this high or low orbit? Navbal is orbit-relative so in "faster" orbits ship's will noticeably rotate in relation to orbit direction - actually its orbit direction vector rotating, while ship stays stationary. But this always was the case as far as I remember.

Edited September 9, 2015 by RidingTheFlow

[peachoftree]

You might have trim enabled, try pressing alt-x and see if it fixes the problem

[Slam_Jones]

I've had phantom input from my joystick too many times to count. May have scrapped a few designs before realizing that was the problem...

If you think it might be caused by the joystick, unplug it once the game has loaded in and everything. Just make sure it's plugged in when you start the game, otherwise it gets confused and resets your key bindings.

So:

- Make sure joystick is plugged in

- Start KSP, get to main menu

- Unplug joystick

- Play KSP

If that doesn't do it, then something else may be at play. But at least this way you'll be able to see if the joystick is the problem pretty easily.

[worir4]

You can increase the deadzone on your joystick in the KSP settings. To help with the settings reseting when you unplug the controller, you can make a copy of your settings file and then put it back in to the KSP folder if you need to.

[Netskimmer]

Thanks for the replies. The drift is quite fast and the ship rotates with it so it's not a matter of orbit. I don't know why I didn't think about unplugging the joystick after starting KSP, I will give that a try, I will also check trim setting. I'm at work now, but I will try everything when I get home and let you know if I figure it out.

[Xyphos]

if your ship is rotating while the engines are active, then your Center of Thrust isn't aligned with your Center of Mass and/or your engines are angled incorrectly.

try using the visual aids on the lower-left side of the ship editor.

[Slam_Jones]

if your ship is rotating while the engines are active, then your Center of Thrust isn't aligned with your Center of Mass and/or your engines are angled incorrectly.

try using the visual aids on the lower-left side of the ship editor.

A good way to check that is to have a mod like KER that will display thrust torque (I think MechJeb might display it as well?). Just make sure it's as close to 0 as possible, and all is well.

Edited September 9, 2015 by Slam_Jones

[Netskimmer]

A good way to check that is to have a mod like KER that will display thrust torque (I think MechJeb might display it as well?). Just make sure it's as close to 0 as possible, and all is well.

Thanks for the responses guys. This happens with just the command pod in a vacuum with nothing but the built in reaction wheels. So atmosphere and thrust shouldn't be a factor.

[Xyphos]

Thanks for the responses guys. This happens with just the command pod in a vacuum with nothing but the built in reaction wheels. So atmosphere and thrust shouldn't be a factor.

oooooh, maybe your pod ran out of Electricity, you should attach more batteries and/or solar panels to your pod(s)

try right-clicking your pod and checking the electric levels.

[T.A.P.O.R.]

You can increase the deadzone on your joystick in the KSP settings. To help with the settings reseting when you unplug the controller, you can make a copy of your settings file and then put it back in to the KSP folder if you need to.

This!

happened to me a bunch.

[Netskimmer]

It still happens without the Joystick plugged in, so I'm assuming that isn't the issue. Alt-X also did nothing. It seems tied to SAS. I can get the craft mostly stable and then hit SAS and the rotation starts. If I tell Jeb to hold prograde, it tries but can't quite stay on the prograde marker and wobbles, like it's fighting an opposing force, when I set it back to regular stability assist, it goes back to rotating. I started a new sandbox game to test things and it does the same thing.

[Slam_Jones]

Hmm a picture of the craft in question might help at this point.

[Netskimmer]

Hmm a picture of the craft in question might help at this point.

Mk I command pod in low, stable orbit. Nothing attached to it except basic parachute.

[Slam_Jones]

Just for curiosity sake, try attaching a small reaction wheel and see if there's any change.

[Netskimmer]

Just for curiosity sake, try attaching a small reaction wheel and see if there's any change.

Put a large one on, exact same behavior.

[Highlad]

And you're sure it's not a matter of accidentally setting a slight trim?

--edit--

Re-read through your posts, your right, it doesnt sound like a trim issue.

Edited September 10, 2015 by Highlad

[cantab]

It still happens without the Joystick plugged in, so I'm assuming that isn't the issue. Alt-X also did nothing. It seems tied to SAS. I can get the craft mostly stable and then hit SAS and the rotation starts. If I tell Jeb to hold prograde, it tries but can't quite stay on the prograde marker and wobbles, like it's fighting an opposing force, when I set it back to regular stability assist, it goes back to rotating. I started a new sandbox game to test things and it does the same thing.

The "jitter" on the hold prograde and similar is a known issue, those functions are a bit crude and struggle with ships that have either much more or much less torque for their size than average. The rotation on regular SAS is weird though.

If you use FAR, check you haven't left the Flight Assistance tools on!

[Netskimmer]

I tried the Mk2 pod and got the same result. Here is a list of the mods I'm currently running.

Toolbar

Chatterer

Kerbal engineer

Protractor

SCANsat

All but toolbar are updated to run with the latest version, and though it says it is not compatible, from what I've read that's normal and as far as I can tell, it works fine.

[p1t1o]

The little pointers in the bottom left when you are focused on your ship, are they registering any control inputs, or is the force seemingly coming from nowhere? As if you were in an airflow?

Does the force persist if you disable reaction wheels? Try disabling them and briefly going into 5x warp to stop any rotation, and see if it starts up again.

You definitely dont have an engine attached? The last time I experienced phantom forces, it was a weird interaction between mechjeb, reaction wheels, engine gimballing and a very, very off-centre CoM. Disabling all of those things and re-enabling just the things I wanted, fixed the problem - that time anyway.

Protractor is the only mod on the list that I dont have installed, does it have any autopilot features? Is it trying to point you towards a manouvre vector or something like that?

How are you going to de-orbit if you have no engine? If you are already on an entry trajectory, my advice would be, just re-enter, hope you survive and hope it doesn't re-occur!

[The Yellow Dart]

Man, you've got a toughy here. Could it be stuck arrow keys? Have you tried any other games since this started, or noticed any other weirdness besides in KSP? If not I guess I'd try a fresh install, no mods, and a new game and try it out, then try transferring your save file over.

[Netskimmer]

Turning the reaction wheels off does stop it from happening. If I bring the craft to a dead stop and reinitialize SAS, I see a small bump in the control input indicators in the bottom left of the screen. I have also noticed that if I pull the stick to the left and release it, the indicator just returns to neutral, but if I pull the stick to the right and release it, the indicator pops over the neutral line to the other side for a split second before returning to neutral. It feels like the game is overcompensating for some reason. I have been playing other games without any indication of a problem and the inputs in my joystick calibration software look normal.

I guess when I get home I can do a clean install and see what happens.

As to the questions about the craft having no engines and being in orbit ect. When I first realized I was having an issue I started a fresh sandbox game and I am testing things by putting a command pod into orbit without any intention of bringing it back. (just reverting the flight) That way I can have as few components as possible on the craft to try and isolate the cause.

[sal_vager]

Hi Netskimmer, can you test your vessel in an unmodded KSP or will it not load without the addons?

Also, if you upload your KSP.log, output_log.txt, and the affected save we may be able to figure it out from that.

If you hold alt and press F2 you can open the debug log, it may show what's going on.

[Netskimmer]

I'll give that a try when I get home tonight.

[Netskimmer]

Ok, I think I know part of whats going on. If I am perfectly still, SAS seems to work fine. If there is any movement when I activate SAS, the ship/nav ball begins to vibrate/oscillate. Whatever direction the ship is oscillating toward at the moment I turn SAS off, it just keeps moving in that direction [the drift I spoke of] since there are no outside forces to interfere. I need to figure out what is causing the oscillation when SAS is active.

I did a complete, clean install with no mods and tested with the joystick plugged in and without, and there is no difference in the behavior.

Can anyone recommend a good place to upload the log files to? I don't see way to attach files to these posts directly.