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Bug #4782

SAS advanced stability features cause wild jittering

Added by paulcd2000 over 9 years ago. Updated about 8 years ago.

Status:
Moot
Severity:
Normal
Assignee:
-
Category:
Controls and UI
Target version:
-
Start date:
04/28/2015
% Done:

0%

Version:
1.0
Platform:
Windows
Expansion:
Language:
English (US)
Mod Related:
No
Votes:
Arrow u r green
Arrow d r red

Description

Hey all,

It looks like there's a bug of some sort in the new SAS code. I removed my old install of KSP, installed 1.0 through steam, started a new sandbox mode, and launched a small craft into space. When I got there, I turned on Prograde assistance (that I got from having a level 3 pilot) in my SAS. [[http://www.gfycat.com/AbleClearcutBallpython]] was the result. It seems that my control surfaces and engine gimbal oscillate wildly around the target direction. This happened in every direction I tried (including maneuver node mode, but I didn't try target directions). Later, when I went to reenter, I found a similar (worse) problem: [[http://www.gfycat.com/IllustriousValuableBoa]]. It seems that in addition to the jitter, this caused the craft to rotate past the target orientation.

I have a saved game that I can easily get in this state, if you need any additional debugging information.

History

#1 Updated by orcaman98 over 9 years ago

  • Status changed from New to Confirmed
  • % Done changed from 0 to 10

I've observed this, too. I think it's the same thing that affects the Stability Assist, just a bit more subtle in the latter case. I used to think it was a control algorithm problem, like not using a proportional-integral-derivative controller, but it looks like it stabilizes on some ships now. Used to be, you could watch RCS go crazy pulsing too hard, and overshooting the mark, and then pulsing too hard the other way, and you still can, but not always. New theory - bendy ships. I still think the flexibility of part connections is exaggerated, and that wobbly-ness may be what keeps the autopilot from stabilizing in some cases. Not an excuse for the Mk I pod in your video, though. That might be related to the "sneezes" aircraft experience in flight, though.

#2 Updated by Squelch about 9 years ago

  • Platform Win32 added
  • Platform deleted (Windows)

#3 Updated by TriggerAu over 8 years ago

  • Status changed from Confirmed to Needs Clarification
  • % Done changed from 10 to 0

#4 Updated by orcaman98 about 8 years ago

So, in a bug that I reported personally, you linked the forum post about the cleanup, which I read, and found this in the comments. (as "core functionality affecting") LOL I guess only things I originated are listed under "My Issues"? Anyway, I'm pretty sure it was still going on when I tested the SOI thing, though I'd learned to tune it out, so I'll pay attention when I work on the other things. I'll also check the sneezes, and list a bug if there isn't one already. In case I forget when I return, add Win64.

#5 Updated by TriggerAu about 8 years ago

  • Status changed from Needs Clarification to Moot
  • % Done changed from 0 to 100
  • Platform Windows added
  • Platform deleted (Win32)

Gonna close this one out as Moot, cause there is new SAS code in the next version as per the weekly dev notes.

If we find weird behaviour in SAS in 1.2 it wont be the same cause/code as this, but I wont solve it as closed

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