Help Making Wheels Act Like Wheels (Not Toboggan on Grease)

[Srpadget]

Apologies in advance for the more-ranty parts of this post.  I'm frustrated to the breaking point, and almost ready to just give up on KSP after countless thousands of hours over the last 6(?) years...

People say the hardest basic skill in KSP is rdzvs/dock.  I disagree--the hardest basic skill nowadays appears to be working with wheels.  (They get MORE borked, not less, each time KSP updates to a newer version of Unity.  What's up with that?)

I understand it is apparently possible to manually adjust the various wheel-control settings, via lengthy trial and error.  But apparently the settings typically do NOT do what you'd think they do from what it says on the label...?

At the moment, what I appear to need is some way to increase the friction/grip/traction (I am not a 'car guy', so those are doubtless technical terms which have very specific definitions in the automotive community but which I'm inadvertently misusing; sorry about that) between the wheels and the ground.  Right now, I don't seem to be able to create a wheeled vehicle, large or small, which is capable of gripping the ground well enough to do much of anything except slide sideways across the ground (usually downhill, sometimes UPhill, sometimes I'm not sure if it's up or down because the ground appears to be locally flat and level), often with bonus spinning if I did something foolish like try to steer with SAS off.  (Note that 'steering' is currently accomplished by reaction wheels, as wheel-based steering accomplishes nothing--even when the front end of the vehicle happens to be more-or-less-stably aligned with the direction of skid.)

I should emphasize here that I am NOT trying to create some supercar that turns on a dime while zooming over rugged terrain at aircraft-like speeds.  Repeat, NOT trying to do that.

I'd be reasonably content if I could put together a small, light ( <1 ton) vehicle that could travel 5-10 meters/sec on level terrain, successfully navigate modest hills at lower speeds (even 1 or 2 m/sec), steer using wheel controls, and brake to a stop.  Preferably a full stop, but at minimum with a small enough 'slide speed' to allow a save and/or change of focus to a different vehicle/scene. 

Added bonus would be a larger (~40 ton) vehicle capable of trundling along for ~100 meters at ~1 m/sec on reasonably flat/level ground (what passes for flat/level on the Mun--not going to ask the impossible and insist on what passes for 'level' on Ike!) and return to its starting point.  And, y'know, STOP.  Well enough, at least, to allow me to shift focus away from that vehicle, do something else, and come back to it later.

I don't WANT to spend countless hours tinkering with wheel controls, via trial-and-error,  for every single vehicle design and every celestial body (I thought I was buying Kerbal SPACE Program, not Kerbal WHEEL AND TIRE OPTIMIZATION Program, after all), but apparently that's what's required.

So  is there a guide somewhere that at least says what each control nominally DOES, so I have some clue how to proceed?  (I do know that you can't trust the labeling on the controls...)

What I know so far:

• Adjusting the "spring" does not change the "spring constant" that we learn about in high-school physics.  It apparently invokes an "upward force" on the suspension (which I guess is kinda-sorta like a 'spring' if you don't think too hard)
• Adjusting the "damping" does not change the "damping constant" that we learn about in high-school physics.  It apparently invokes a "downward force" on the suspension (which has NOTHING to do with 'damping' as far as I can tell)
• Adjusting the "traction" does not change either the static or dynamic friction of the tire/ground interface. It apparently invokes an anti-skid system akin to an automotive ABS (anti-lock braking system), with a larger numeric value driving a more-aggressive, more-sensitive reduction in power applied to the wheel.  So INCREASING the "traction control" actually REDUCES the vehicle's ability to start, stop, climb, etc.--but (I would assume) primarily under more-challenging conditions, NOT low speeds on flattish ground...?
• No idea what the other controls actually do, but at this point I'm reasonably confident that whatever I conclude from the name of the control will be wrong

Mind you, the above is what I've been TOLD.  Left to my own devices, I'd come to the conclusion that those are just placebo 'controls' that actually do nothing at all...

So are there ANY useful tips/pointers beyond 'try every possible setting of every possible control in every possible combination, and HOPE'?  Or should I just let my frustration get the best of me, and give up wheeled vehicles as a bad idea?

[Guest]

This sounds ... odd. I just finished a probes-only career in 1.9.0 where I sent light rovers to the Mun, Moho, Tylo, and Eeloo, and they worked perfectly well -- easy to drive and handled well up to about 25 m/s, no problems turning, braking, or accelerating, and I didn't do anything particularly exciting with the wheels apart from sticking them on. (Okay, I do think I might have messed a tiny bit with the spring strength to fine-tune the handling, but they worked perfectly fine even with everything at Auto.)

Do you have a picture or even better a craft file to share? That would help troubleshoot. Here's the one I used: 

Edit: possibly dumb question, but... which way is your control point pointing? Or, put another way, does your navball show a horizon in the middle? If not, the problem isn't with the wheels, it's with the steering controls: the control point has to point forward, otherwise it just won't work. The reaction wheels might make it turn cartwheels but it won't behave much like a wheeled vehicle.

Also, turn the reaction wheels off or set them to SAS only, otherwise your vehicle will lean forward when accelerating and back when braking, and if your reaction wheels are too strong that might make it uncontrollable too.

Edited February 29, 2020 by Guest

[bewing]

First, you need to make sure your vehicle is not "microbouncing". Under many circumstances, on low-G worlds, the suspension settings will cause all four wheels to be constantly bouncing above the ground by a tiny distance. If they are not touching the ground, then there is no friction (duh). Generally you do this by choosing wheels appropriate to the mass of the craft and then adjusting the "spring" setting.

Second, the setting you want is called "Friction", in the menu. It probably says "Friction: Auto", with a button. Click the button once so that it says "Manual". It will then give you a slider to adjust. Push it up to the maximum (5), and see if that fixes things.

"Traction" is something different. Traction applies the brakes to keep your motors from making the wheels spin out. It is almost always counterproductive, so your best bet there is almost always to turn it off.

Spring makes the springs softer. Damping is black magic, that you tweak blindly after you set the springs to the correct softness for the ride you want. So sorry, but these are Unity/VPP values that are exposed directly to the user, and KSP has no control over how they work.

 

[Srpadget]

bewing's "fix microbouncing by tweaking springs first, then damping" seems to have helped.

Fussed with various settings on my (current) 'problem child';  seems that my early efforts to the get thing to STOP by maxing out the "Brakes" setting to 200 was a bad move that CAUSED a bunch of juddering/bouncing.  Friction (at least on the itty-bitty Model S2 wheels for my half-ton Ore prospector) actually maxes out at 8.2, not 5--and it' was already up at 8.2. The "Spring Strength" was at a very low value--dunno if that was what I'd tuned it to during a similar but less severe set of issues back in V1.7 (seems unlikely) or if I'd messed with them earlier today (I don't think so, but I might have), but it seems to 'want' to be between 1 and 1.5 or thereabouts for 4 S2 wheels under a 1/2-ton mass in Mun gravity.

So the prospector appears to be behaving itself, at least for now.  Will see what happens when the same design reaches Minmus.

I gave up on salvaging my old standby ISRU base (~25 tons empty, ~120 tons with all tanks full), and replaced its LT-2 landing legs with Breaking Ground robotic pistons and grip pads; that seems to have fixed its newfound (in 1.8) tendency to spin in place at ~1 complete revolution every 5 minutes or so.  And since it doesn't need to MOVE after it lands, it really wants to be basically glued to the surface.  (I wonder what would happen if I got rid of the pistons, and just plastered grip pads onto its bottom surface?  I tried landing it directly on tankage once, back in V1.0.something...it was not pretty.  Nothing exploded, but all the parts broke apart, like all its joints had been made of spun glass!)

Will see what happens with the (~40 tons fully loaded, 8 TR-2L Ruggedized wheels) LF/O tanker truck, when it lands.  I *started out* a bit concerned about that one, as it's been troublesome even in past versions, when other vehicles currently giving me headaches were just fine...

[FlyingGeeze]

Spring/Damp settings are arbitrary. The great rule of thumb is that the spring/damp settings accomodate their range based upon the type of wheel, the amount of any such type of wheels based on the total weight of the vessel.

Not any vehicle behaves the same using the same spring/dampening settings on any other celestial body then the one you tested the settings on. 

As for stuttering and sliding, it seems slight changes of 0.1 to the spring or dampening can completely kill any bouncing effect. So within the range of 0.1 to 5 on the spring/damp settings a 0.1 change can mean a good ride or a bad one.

To my experience, setting "friction" to 5.0 on your wheels makes sure your vessel doesn't slide, 'if' the spring/dampening settings were calibrated first of to make sure nothing would bounce. My experience is to setup my rover in that particular order. Making sure that nothing bounces by doing a "cheat menu" lander test on the target planet/moon to make sure the settings are properly calibrated, and then use 5.0 friction settings on the fly to make sure the vessels are properly anchored.