1.4.2 Landing Legs = Craft Wiggle

[klesh]

Upon further investigation:  All landing legs are causing this wiggle for me in 1.4.2

 

I believe the fix for the LT-1 landing legs is causing a problem.  Its very easy to reproduce.

 

1. Create even the most basic vehicle and include these any legs.  Probe core, fuel tank, 4 legs.  Can be either the SPH or VAB.

2. Launch the craft.

3. Observe it wiggle without any input from the player.

 

The craft will load in, physics will ease in.  2-3 seconds later the legs will jump up, you will see your craft raise up a little, and then the neverending wiggle begins.

You can make the craft so it can hop off the runway or launchpad and land on the grass 100m away.  It will still wiggle.

 

Here is a quick video showing the wiggle on all 3 leg types:

 

 

 

 

 

 

Edited March 29, 2018 by klesh

[HeleleMama]

This can also be seen on planes with landing gear LY-35 and LY-60.   In low gravity environment, your craft will be pushed high into the sky.

Actually you don't need to load the game.  Time acceleration and stop will do the same. 

 

 

[klesh]

Thats not the issue I'm talking about.  Look closely in the video, the entire craft shakes no matter what legs are on it. 

[HeleleMama]

2 hours ago, klesh said:

Thats not the issue I'm talking about.  Look closely in the video, the entire craft shakes no matter what legs are on it. 

Yes, but in your last one, you can see the leg is clipped into the ground and get pushed out.

My craft is not shaking but the clipping and bouncing effect is the same.

 

I thought they share the same root cause.

[LameLefty]

Probably related - last night I was testing potential designs for a Laythe lander (Cheat Menu editing it into low Laythe orit). As soon as the craft spawns on the launchpad before I can edit it, at least one or more landing legs will explode with the log message that the part collided with the ground. Similarly, when the craft lands on Laythe at a whopping 0.1 - 0.5 m/s, at least one or more legs will explode with the same log messages. 

This leg fragility wasn’t occurring with 1.4.1. 

[thelsien]

I was getting into KSP again, and I wanted to go through the tutorials. I finally arrived to the 'From Mun' training mission, and EVERY TIME the ship, which is parked on the Mun, is jumping up, without any legs. I don't have control over the ship yet, because of tutorial reasons. Is this a 1.4.2 bug?

[Just Jim]

The landing leg issue has been an off/on thing as long as I can remember. Try auto-strutting your legs. I ran into it again recently and that seemed to clear it right up.

[thelsien]

I just checked again the logs in the game. It says: LT-05 Micro Landing Strut has crushed into Terrain.

Right after the tutorial mission starts. I am using the most recent version of the game. But I believe my issue is not the same as the described above.

[basic.syntax]

Agree @Just Jim, slight drift/jitter with legs is an old problem. Doesn't mean the issue shouldn't be re-raised every now and then

This old post provides some good advice about how leg values for spring and damper work. 

LT-2 legs seem to be easily crushed in 1.4.2, but that's a separate issue.

 

[Just Jim]

1 hour ago, basic.syntax said:

Agree @Just Jim, slight drift/jitter with legs is an old problem. Doesn't mean the issue shouldn't be re-raised every now and then

I agree, but my understanding of the problem, and bear in mind, I'm not a Dev, but from what I understand it's got something to do with the game physics, and much more tricky to fix than it might first seem. And whenever the game code changes somehow, there a chance it may rear it's ugly head again in some way or another, which seems to be the case again. I know for a fact the "dancing-legs" bug was reported a couple weeks ago, and is being looked at... I was the one that reported it. 

[LameLefty]

9 hours ago, Just Jim said:

The landing leg issue has been an off/on thing as long as I can remember. Try auto-strutting your legs. I ran into it again recently and that seemed to clear it right up.

Auto-strutting is now the default for landing legs and cannot be turned off. Makes no difference with either the bouncing or the "explode as soon as the craft touches the ground" issue (which I still think are inter-related).

[HeleleMama]

The funny part is....The best way to land something stable is to retract the landing gears.

Since some parts have more than 80m/s impact tolerance, Landing gears is not necessary for most of the cases. 

 

Maybe, by just spawning the craft slightly above the terrain's surface plus already existed "Easy the gravity", this can be fixed.

[steve_v]

2 hours ago, Just Jim said:

whenever the game code changes somehow, there a chance it may rear it's ugly head again in some way or another, which seems to be the case again.

Bugs reappearing when changing unrelated code is simply a sign of a messy codebase constructed from band-aids on top of band-aids, and not fixing the underlying cause.
The landing legs went screwey with the new (and much hyped) wheelcolliders in 1.1/UE5. Instead of tackling the (not inconsiderable, but it's been done before) work of ripping the lousy thing out and implementing something that works, SQUAD has been sticking fragile plasters on it ever since.
Self-exciting bouncing landing gear, exploding landing legs, phantom forces, "wiggling" while landed, craft-o-pault on scene-load, it's all the same issue.

 

33 minutes ago, LameLefty said:

Auto-strutting is now the default for landing legs and cannot be turned off. Makes no difference with either the bouncing or the "explode as soon as the craft touches the ground" issue (which I still think are inter-related).

"Auto-strutting" is the latest ridiculous band-aid.
And they almost certainly are, though I can't see the code to prove it.

Edited March 31, 2018 by steve_v

[Just Jim]

1 hour ago, LameLefty said:

Auto-strutting is now the default for landing legs and cannot be turned off. Makes no difference with either the bouncing or the "explode as soon as the craft touches the ground" issue (which I still think are inter-related).

I'm trying to think, and it may have been I auto-strutted the tank the legs were attached to.... sorry. It was a couple weeks ago, and I know it's not a perfect solution, but in my case it worked.

50 minutes ago, steve_v said:

Instead of tackling the (not inconsiderable, but it's been done before) work of ripping the lousy thing out and implementing something that works, SQUAD has been sticking fragile plasters on it ever since.

OK... STOP right there.

Do NOT, under any circumstances, seek to draw me into any kind of "squad-bashing" conversation whatsoever!!! EVER!!! You are preaching to the wrong person, brother! 

In fact, congratulations... this is the very last time I ever try and help anyone. 

Edited March 31, 2018 by Just Jim

[klesh]

The reason I posted the video is the craft wiggling I am experiencing is a first for me, going all the way back to .23, I've never seen the kind of shaking like I'm seeing now.  

[steve_v]

1 hour ago, Just Jim said:

Do NOT, under any circumstances, seek to draw me into any kind of "squad-bashing" conversation whatsoever!!!

Draw you in? Hardly. You commented that these bugs keep coming back, I explained why that is.
SQUAD knew about the issues with the new wheel system, and chose to plaster over it with autostruts and disabling collisions, that's not "bashing", it's simply what happened.
The wheel collider is designed with simple 1-part vehicle driving games in mind, no quantity of tweaks will change that, and trying to hack around it's limitations results in a finely balanced and fragile system. This is why it keeps breaking.

The wheel implementation in Unity (which landing legs also use) doesn't behave anything like an actual wheel. If you can tune it to a particular situation it works okay, but if it has to deal with random player-made craft it wigs out badly. Autostruts are an attempt to get closer to that one-part ideal that the system works well with, and the rest of the "fixes" are just tweaking parameters in a vain attempt to find a setup that works for every craft. IMO, that's never going to fix the root-cause.

 

30 minutes ago, klesh said:

the craft wiggling I am experiencing is a first for me

At a guess, again without seeing the code, I'd say that the finely balanced artificial forces SQUAD applied to fix stuff sliding around are no longer finely balanced...
I seem to recall seeing something similar in one of the prereleases, though I can't find the reference now.

Edited March 31, 2018 by steve_v

[klesh]

1 hour ago, steve_v said:

At a guess, again without seeing the code, I'd say that the finely balanced artificial forces SQUAD applied to fix stuff sliding around are no longer finely balanced...

I seem to recall seeing something similar in one of the prereleases, though I can't find the reference now.

 

 

Yes, I do recall the version where ships would straight up slide across planetary surfaces, up hills and whatnot, and that did implement a fix for it.  I'm at a loss as for why this new wiggling is happening, I just don't expect this kind of stuff in a post 1.0 environment.  Technically I do expect it from this game at this point, but I (we) shouldn't have to expect it.

[steve_v]

16 minutes ago, klesh said:

I just don't expect this kind of stuff in a post 1.0 environment.  Technically I do expect it from this game at this point, but I (we) shouldn't have to expect it.

Indeed. If I come across as particularly salty at the moment, here's why^.
We're not in beta any more, and the prerelease idea seems to have fallen by the wayside. I expect more testing and fewer regressions for a release at this point, especially when Take Two has just purchased the game and the first DLC has arrived.
Problems with the DLC itself, fine, but the core game should be relatively stable. 2 year old bugs resurfacing now is ridiculous.

Edited March 31, 2018 by steve_v

[Just Jim]

6 hours ago, steve_v said:

SQUAD knew about the issues with the new wheel system, and chose to plaster over it with autostruts and disabling collisions, that's not "bashing", it's simply what happened.

Is this what happened? And you know this... how? Because I don't recall seeing you on the DEV team.

Your implications are transparent.

Good day

[steve_v]

26 minutes ago, Just Jim said:

And you know this... how?

a) By discussing it with one of said (former) devs.

b) By mucking with the thing myself.

c) In the course of looking for alternatives, of which none are are available as a ready-to-use plugin, hence the "not inconsiderable work" comment.

If you have some credible evidence to the contrary, I'm listening. Do you have an alternative explanation for the forced autostruts on wheels, or why kerbals can walk through landing struts?
Perhaps it's just space aliens messing with a perfectly engineered codebase, rather than a set of imperfect patches on top of an imperfect system?

33 minutes ago, Just Jim said:

Your implications are transparent.

My implications are that SQUAD has built a thing on top of a system that, frankly, sucks. And this is why the bugs keep coming back. If you want a second opinion, go check out all the complaints on the Unity forums about just how hard the wheel system sucks. Or you could just keep on being angry, suit yourself.

[Just Jim]

1 hour ago, steve_v said:

My implications are that SQUAD has built a thing on top of a system that, frankly, sucks.

1 hour ago, steve_v said:

Or you could just keep on being angry, suit yourself.

I am only annoyed because I came onto here to try and offer the OP a solution to the problem. Whether it's temporary, or in your words, a "band-aid" is irrelevant!!! I only tried to help him with something I know worked for me! And that is ALL!!!  

Again, you are the one trying to turn this into some drawn out dissertation on why Squad isn't doing what you think they should do... and while I respect your right to have an opinion, I refuse to participate.

And so again, Good Day.

 

Edited March 31, 2018 by Just Jim

[steve_v]

1 minute ago, Just Jim said:

I only tried to help him with something I know worked for me

The only suggestion you have offered is to "autostrut the legs", which is on by default anyway.
Then you offered a vague "It's probably complicated" explanation as to why this bug is still around, which I attempted to clarify as I had investigated the new wheels / landing legs in some detail around the 1.1 release.
Why this then needs to become a big angry argument, I don't know.

16 minutes ago, Just Jim said:

And that is ALL!!!

And I claimed you said something more, perchance?

10 minutes ago, Just Jim said:

you are the one trying to turn this into some drawn out dissertation on why Squad isn't doing what you think they should do

I'm not telling anyone what to do, I simply explained what they have done and why wheels / legs still suck. As this topic is about yet another bug relating to landing gear, I don't think that is at all off topic.

4 minutes ago, Just Jim said:

I refuse to participate.

So don't. You're the only one shouting in here. If you want to defend against these perceived "SQUAD bashers", that's your prerogative, but don't yell at me.

 

[Just Jim]

I'm done... I quit... I tried to say that earlier. I'm not going to argue... or help again. 

Have a good weekend

[JPLRepo]

If people are able to raise bug reports (or even better add to existing bug reports) with craft files and save files that goes a long way to help us resolve the issue.

https://bugs.kerbalspaceprogram.com/issues/18286
https://bugs.kerbalspaceprogram.com/issues/18289

[Jungfaha]

1 hour ago, JPLRepo said:

If people are able to raise bug reports (or even better add to existing bug reports) with craft files and save files that goes a long way to help us resolve the issue.

https://bugs.kerbalspaceprogram.com/issues/18286
https://bugs.kerbalspaceprogram.com/issues/18289

Raising awareness of issues. That's great Can we do that with Lyme Disease too? Oh wait... that's a different subject.

Ahem, yes ill be checking these links out. I'm afraid all i could do is vote them up. and attempt to encourage others to use the bug tracker as well.

For now there is a "BAND AID" that some have talked about, which  fixes the fragile landing gears. Though on the console log 4m/s for us is 30 -38m/s thus why the legs are breaking (guessing its the physics). So some basic .cfg files were adopted.