the rover's wheels turn differently

[antipro]

It's long time I don't build a rover, so I could be confused about this but,
as the title says, rover's left and right wheels turn in a different way.
different way how? if I turn left, the left wheel seems to turn more angled than the right one,
viceversa If when I turn right the behavior is symmetrical from the opposite side, in short the right wheel turns more.
this is an assembled on EVA rover but the same rover built in the VAB behaves the same way.
I could be wrong but I remember both L/R wheels turned with the same angle.

So, idk, it's an optic effect that I can't figure out or a normal behavior?


another question, since now I'm here talking about driving this rover on ike,
the rover drives very well in kerbin gravity but on Ike is almost uncontrollable,
it's like it slides on ice. I would think the low rover mass together with low surface gravity make the rover uncontrollable,
I've tried it on the Mun too, that is just a bit more massive than ike, and the rover is still uncontrollable.

So, any tips to have more surface grip on these low gravity moons?

Wheels on ike:
https://www.dropbox.com/s/l2kminhwu09sosp/wheels on ike.mkv?dl=0

Rover manoeuvrability on ike and mun:
https://www.dropbox.com/s/fanyjxx8etcq6x5/rover on ike.mkv?dl=0
https://www.dropbox.com/s/7vfs102cxfcicym/rover on moon.mkv?dl=0

Edited December 25, 2020 by antipro

[bewing]

Well, I'm not sure about your steering issue. It may be a bug in the game. Like you say, it may just be an optical effect. I will have to test it myself to see.

 

For your grip issue, the answer is the "Friction Control: Auto" in the wheel's menus. Click it to "Manual" and then turn it up a lot. You might think that's what you did with the "Traction Control" -- but traction control is something completely different (it has to do with brakes, not friction). Truly, you probably want to turn the Traction Control off (slide it down to zero).

[jimmymcgoochie]

The wheels turn to different angles because they are trying to make your turn radius as small as possible. If you’re going right then the wheels on the right side need to have a smaller radius than those on the left, so they turn more to follow that radius. Four/all wheel steering makes this more pronounced than if you disable the rear wheels’ steering and drive more like a real car with just the front wheels providing the steering, though doing that makes your turns longer and wider.

If your wheels are skidding or sliding then override friction control and turn it up higher; if you get a lot of wheel spin or start wheelie-ing (is that a word?) then turn on SAS to keep the wheels in contact with the ground- traction control just makes you go slower by reducing the motor torque available at low speeds, so reduce that as much as possible (I often turn it completely off on the front wheels of my rovers) to make them accelerate faster to the point where your solar panels etc. can charge the batteries even while you’re accelerating flat out.

[Snark]

On 12/24/2020 at 10:00 PM, antipro said:

rover's left and right wheels turn in a different way.
different way how? if I turn left, the left wheel seems to turn more angled than the right one,
viceversa If when I turn right the behavior is symmetrical from the opposite side, in short the right wheel turns more.
this is an assembled on EVA rover but the same rover built in the VAB behaves the same way.
I could be wrong but I remember both L/R wheels turned with the same angle.

So, idk, it's an optic effect that I can't figure out or a normal behavior?

This is deliberate, designed behavior in order to achieve correct steering.  It was introduced in KSP 1.1.  From the release notes for 1.1:

On 4/19/2016 at 12:43 PM, KasperVld said:

* Steering model features true Ackermann steering.

 

https://en.wikipedia.org/wiki/Ackermann_steering_geometry

 

[antipro]

8 hours ago, Snark said:

This is deliberate, designed behavior in order to achieve correct steering.  It was introduced in KSP 1.1.  From the release notes for 1.1:

ah! this explains why I remember never seeing it in ksp before.
and anyway even in real life, I have never heard of it, the wiki page is not even translated into my language.
I always thought the steering angle issue was handled by the https://en.wikipedia.org/wiki/Differential_(mechanical_device) only.
however, even though I have already heard of the Differential and even Ackermann now, both the concepts are out of reach for my mind.
Both involve complicated geometric and mathematical concepts.
consideration: I trust it and it certainly works but seeing that high difference in angle between the inner and outer wheel, it seems exaggerated.

Edited December 26, 2020 by antipro

[Snark]

1 hour ago, antipro said:

I always thought the steering angle issue was handled by the https://en.wikipedia.org/wiki/Differential_(mechanical_device) only.

The differential is also important, but it serves a complementary purpose.  The vehicle's wheels come in pairs (on the left and right side).  When the vehicle is traveling in a straight line, the left and right wheels spin at the same rate.  However, when the vehicle turns, the left and right wheels need to spin at different speeds-- the wheel on the outside of the turn needs to rotate more than the wheel on the inside of the turn, since it travels farther.

To get "correct steering", where no wheels end up "skidding" on the ground, therefore, it's necessary that each wheel be rotating at the correct speed, and pointing in the correct direction.

• Ackermann steering is what allows the wheels to all be pointing in the correct direction
• The differential is what allows each wheel to rotate at the correct speed.