Odd reaction wheel behavior - oscillating roll torque

[Streetwind]

Hey all. This isn't a normal support request, because it's an issue I can solve myself (by restarting KSP). But I was very surprised to see what I was seeing, and I'm interested in finding out if someone's seen something similar before, and knows what may have caused it. Maybe that'll help me prevent it reoccuring in the future.

Yesterday, as I was coming out of an aerobraking pass of a manned Mun lander returning to Kerbin in my heavily modded install (32bit client on Windows), I noticed something odd: the craft appeared to oscillate slightly when I was steering it. This surprised me, because SAS was on, and that usually takes care of anything beyond joint wobble. The craft consisted mainly of a LV-909, an empty fuel tank, landing legs and a couple of science instruments, meaning that the reaction wheel torque in the basic 1-man pod was easily enough to comfortably control and steady it.

My surprise then grew much bigger when I turned off SAS. Immediately, the craft started rolling clockwise... and then, half a rotation later, stopped, and rolled counterclockwise instead. Again, half a rotation later, it stopped, and went back to roll clockwise. Back and forth, back and forth, and very rapidly so. As long as SAS was on, this was dampened out, but as soon as I turned it off, it went right back at it, like some kind of deranged robotic nursing cradle.

Now I've had experiences with induced torque and phantom forces in the past, usually from part clipping. But there's a couple reasons why I believe this is not the case here:

1.) I did not actually clip parts in this lander. in fact, it was a fairly generous build, with no need to squeeze components into tight quarters anywhere.

2.) It wasn't just a phantom force pushing the craft to veer or turn into one direction - it was an oscillation. I've never seen a phantom force reverse direction with the precision of a pendulum before.

3.) I could see steering input in the roll section of the UI in the lower left corner. It flipped back and forth, back and forth. With SAS on, it remained stuck in one corner, but with no roll happening. I pressed Alt+X to remove any sort of trim, not that I expected that it would work... and indeed, it did not, even after manually adding some trim and then zeroing it out again.

4.) The final reason is also the biggest one: the culprit was the reaction wheels themselves! Rightclicking the capsule and selecting "toggle torque" immediately fixed everything. No more oscillation, the control input was perfectly calm and centered, SAS status on or off did not cause any further changes in behavior. The craft was inert in orbit as it should be. Of course, I had no control authority at that point, and I needed to make adjustments to my orbit, and so I turned the reaction wheels back on. Boom, the rabid oscillations were back instantly!

No other crafts of mine were affected. it was only this one, exclusively. Also, after decoupling the body and leaving only the capsule with its parachutes, the problem still persisted.

Switching to different crafts, going back to the space center or even to the title screen changed nothing. However, restarting the KSP client as a whole fixed the problem. I was able to safely land the capsule afterwards with no further oddness.

Now I'm really curious as to what the heck happened here Is this a known bug, or as yet unheard of? I can provide my full modlist if necessary, but it'll have to wait until I can get home, as it has a very long list of small convenience plugins (like KAC and Flight Indicators etc). FAR and Deadly Reentry are present, as are RemoteTech and TAC LS. Parts-wise I have KW Rocketry, the Near Future suite of packs, DMagic Orbital Science as well as Station Science, SCANsat, RLA Stockalike and a few others.

Edited December 4, 2014 by Streetwind

[Vaporo]

Weeeeeeeeeeeeeeeird. Nope. Never seen anything like this. It sounds like it is connected to some kind of autopilot or control mod, so could we see your mod list?

[Streetwind]

The only piloting aids I have installed are FAR's builtin stability assists (not relevant in space) and RemoteTech's flight computer functionality (not relevant on a craft without a probe core).

But sure, I'll list the full mod selection later-on when I get back home.

[Streetwind]

Alright, so: mod list.

Toolbar

Active Texture Management

MKS/OKS and all the three dozen things it bundles, like Firespitter, ORSX, USITools, CIT etc.

Karbonite

CrossFeedEnabler

Deadly Reentry

DMagic Orbital Science

Extraplanetary Launchpads, with WombatConversions for Karbonite compatibility

Ferram Aerospace Research

Fine Print

Improved Chase Cam

RasterPropMonitor

Kerbal Construction Time

Kerbal Engineer

Kerbal Flight Indicators

Kerbal Joint Reinforcement

KerbalStats

KW Rocketry

Docking Port Alignment Indicator

Near Future (Construction, Electrical, Solar, Propulsion)

PlanetShine

RCS Build Aid

RemoteTech

RLA Stockalike

SCANsat

Science Alert

Stockalike Station Parts Expansion

Station Science

Stock Bugfix Modules

TechManager, loading Mod-Oriented Tech Tree

Texture Replacer

TAC Life Support

Trajectories

TriggerTech (Kerbal Alarm Clock, Alternate Resource Panel, Transfer Window Planner)

ModuleManager

All were freshly downloaded when I made this install (2-3 weeks ago).

[Vaporo]

The only piloting aids I have installed are FAR's builtin stability assists (not relevant in space) and RemoteTech's flight computer functionality (not relevant on a craft without a probe core).

But sure, I'll list the full mod selection later-on when I get back home.

Well, check to be certain that you don't have any of the flight controls on anyways. I don't *think* that they can be active in space, but it might be worth checking.

EDIT: I don't see anything in your mod list that pops out to me. Do you have a joystick installed?

Edited December 4, 2014 by Vaporo

[Streetwind]

I do not, no. My Xbox controller also isn't currently plugged in.

How very mysterious! Have I found an entirely new bug?

[Vaporo]

Have I found an entirely new bug?

Well, It's not a bug unless you can reproduce it. Until then, it's just a glitch.

The definition of a Glitch

The definition of a Bug

Can you reproduce it?

[Streetwind]

I have no idea what caused it, and it hasn't reoccurred since :s

[calut]

I experience same thing, 2 times. 1 time my goo reserch start oscilating with increase amplitude each time. Second time legs of the ship . In both time i force design the ship with goo reserch end legs inside another component(if u try u see a lot of time u can overlap components), so i suspect that is the problem.

...

Nope, i redisign, no overlap, steel same problem when i get close to a moon. Seems those structural frames somehow lose connection, but they dont broke, and make all corps oscilate with exponential amplitude each period.

My mods:

B9_Aerospace

interstelar

DeadlyReentry

KerbalEngineer

MechJeb2

RemoteTech

TweakScale

FerramAerospaceResearch

EnhancedNavBall

is almost the list from http://www.reddit.com/r/KerbalSpaceProgram/comments/1upc6g/scott_manleys_interstellar_quest_modlist/

i was suspected kerbal joint reinforcments, but after delete same bug happen.

Plz help us

Edited December 8, 2014 by calut

[scipiosgoblin]

I’m having the same issue. I’m currently having the problem whenever I revert to either VAB or SPH. The oscillation starts off with small twitches and grows until the craft is uncontrollable and I have to restart. Restart fixes the problem until I revert again. I tend to test builds with several reverts until everything works as I expected. (I call it simulating launches) Then I fly the mission on the final launch.

I thought the issue was caused by my joystick (Saitek X52 Pro), but I unplugged and got the same issue. Not sure what mod or mods are causing. I haven’t played stock enough to determine if it might be a stock bug.

Current System:

Windows 8.1

i7 3.4 GHz 3770 CPU

12 Gb RAM

GeForce GT630

Mods:

Aviation Lights

Chatterer

Mechjeb

Kerbal Alarm Clock

ART

DRE

Dmagic Orbital Science

Docking Port Alignment Indicator

USI Exp Pack

FAR

Final Frontier

FTT

KAS

KAC

KJR

Karbonite +

Infernal Robotics

MKS

Module Manager

Regolith

RLA Stockalike

SCANsat v.9rc4.1

Sounding Rockets

Toolbar

Tweakable Everything

Tweakscale

Universal Storage

Universal Storage KAS pack

ATM

Zero Point Inline Fairings

And all of the stockfixes from that forum thread.

[KeyserSoze]

I’m having the same issue. I’m currently having the problem whenever I revert to either VAB or SPH. The oscillation starts off with small twitches and grows until the craft is uncontrollable and I have to restart. Restart fixes the problem until I revert again. I tend to test builds with several reverts until everything works as I expected. (I call it simulating launches) Then I fly the mission on the final launch.

I thought the issue was caused by my joystick (Saitek X52 Pro), but I unplugged and got the same issue. Not sure what mod or mods are causing. I haven’t played stock enough to determine if it might be a stock bug.

Current System:

Windows 8.1

i7 3.4 GHz 3770 CPU

12 Gb RAM

GeForce GT630

Mods:

Aviation Lights

Chatterer

Mechjeb

Kerbal Alarm Clock

ART

DRE

Dmagic Orbital Science

Docking Port Alignment Indicator

USI Exp Pack

FAR

Final Frontier

FTT

KAS

KAC

KJR

Karbonite +

Infernal Robotics

MKS

Module Manager

Regolith

RLA Stockalike

SCANsat v.9rc4.1

Sounding Rockets

Toolbar

Tweakable Everything

Tweakscale

Universal Storage

Universal Storage KAS pack

ATM

Zero Point Inline Fairings

And all of the stockfixes from that forum thread.

Any luck on this? I've got a lot of the same mods installed, namely mks, far, infernal robotics, module manager, and dmagic and am experiencing the same issue. It seems to happen when focusing on a vessel that has recently reached the SOI of a moon (tested plenty of times with Minmus) - and this may be unrelated, but I've also had the kraken strike when loading the same vessel, or possibly even corrupting the vessel to update it's velocity to 0.0m/s, lock all control and movement of the vessel, and put its trajectory such that there's a straight line from it to the closest celestial body.

Did anyone narrow down where this is coming from?

[KeyserSoze]

Any luck on this? I've got a lot of the same mods installed, namely mks, far, infernal robotics, module manager, and dmagic and am experiencing the same issue. It seems to happen when focusing on a vessel that has recently reached the SOI of a moon (tested plenty of times with Minmus) - and this may be unrelated, but I've also had the kraken strike when loading the same vessel, or possibly even corrupting the vessel to update it's velocity to 0.0m/s, lock all control and movement of the vessel, and put its trajectory such that there's a straight line from it to the closest celestial body.

Did anyone narrow down where this is coming from?

Found out the reason for the kraken attack and the ships being locked to the world space was due to a bug in the Joint Reinforcement mod, which has since been patched and resolved. However, I'm still seeing a weird oscillation of roll torque - after reloading, the ship works fine for about 30 seconds, and then the roll torque gets applied again.

EDIT: Looks like the problem lies somewhere in the Remote Tech dll library - disabling Remote Tech by renaming this file resolves the issue. I'll search their bug list to see what I can find!

Edited January 8, 2015 by KeyserSoze
Looks like the problem lies somewhere in the Remote Tech dll library - disabling Remote Tech by renaming this file resolves

[Tevir]

On 04/12/2014 at 6:16 AM, Vaporo said:

Weeeeeeeeeeeeeeeird. Nope. Never seen anything like this. It sounds like it is connected to some kind of autopilot or control mod, so could we see your mod list?

was my first thought too, that or a joystick mod since the problem must obviously be something that has the ability for control input

On 04/12/2014 at 6:50 AM, Streetwind said:

The only piloting aids I have installed are FAR's builtin stability assists (not relevant in space) and RemoteTech's flight computer functionality (not relevant on a craft without a probe core).

But sure, I'll list the full mod selection later-on when I get back home.

after about 15 hours of headache i have confirmed in multiple installs that it is indeed the FAR stability assists still being active once you are in space. Turn them off and GGWP. Can i have the last two days i spent after work raging at the problem back please?

[sal_vager]

Actually FAR stability assist has been reported to cause this in the past, despite not being relevant in space.

The movement of the pitch, yaw, roll indicators shows there's input from something, the reaction wheels are just applying that input, the same would occur with RCS.

Disable FAR flight assist, even though it shouldn't be doing anything in space, it is.

[Nukeknockout]

Thank you all for looking into this! I'd been getting really odd behavior from VTOLs and spacecraft - when I pressed S the nose went up, and when I pressed W the nose kept going up (Relative to the navball). Disabling FAR's flight stability assists solved it.