Rover flipping in low gravity environments

[NoXion]

So I designed this rover and managed to design an interplanetary transport vehicle for it. But while it handled fine during test on Kerbin, it behaves very strangely when in low gravity:

http://steamcommunity.com/sharedfiles/filedetails/?id=1308598810

Hitting W to make it go forward also cause it to tip forward, as illustrated. How do I get it to stop doing that? I just want the wheels to turn.

Edited February 21, 2018 by NoXion

[Marschig]

1 hour ago, NoXion said:

How do I get it to stop doing that?

Turn Reaction Wheels in command modules to "SAS Only" mode.

[Starman4308]

In addition, consider rebinding your rover controls to different keys than your orientation controls.

[NoXion]

1 minute ago, Starman4308 said:

In addition, consider rebinding your rover controls to different keys than your orientation controls.

There don't appear to be separate rover controls when I look in the settings. What should I be looking for exactly?

[Starman4308]

11 minutes ago, NoXion said:

There don't appear to be separate rover controls when I look in the settings. What should I be looking for exactly?

Settings > Vessel (button near the top) > Wheels.

[Snark]

6 hours ago, NoXion said:

Hitting W to make it go forward also cause it to tip forward, as illustrated. How do I get it to stop doing that?

The problem is that the game's default assignment of controls is pretty silly.  The default assignment is for W to mean "pitch down", and also "wheels drive forward", which IMO is completely ridiculous because those two functions have nothing to do with each other.

What I did on my own machine is to leave WASD controls to control pitch and yaw (i.e. for rotating via SAS), but I re-map the wheel controls to the numeric keypad (8 = forward, 5 = reverse, 4 = turn left, 6 = turn right).

That way, the "reaction torque" controls are completely separate from the rover wheel controls, as they should be, and I have full freedom to make it work however I want.

4 hours ago, Marschig said:

Turn Reaction Wheels in command modules to "SAS Only" mode.

Actually, I would advise specifically the opposite, i.e. I would recommend not doing that.  Especially in the situation that @NoXion has, which is driving a rover on a low-gravity world.

Why do I advise that?

Specifically because reaction wheels are incredibly helpful on a rover when you're on a low-gravity world.  If, for example, I want to turn the rover to the left, I don't have to rely on the wheels to do that-- I can use the reaction wheels to twist the rover to the left.  This becomes really important on low-gravity worlds because when gravity is low, everything becomes "slippery" (friction is less powerful), which means it's easy for wheels to "skid", and reaction torque can become much more useful for muscling the rover around.

Another very common scenario with rovers on low-gravity worlds is that it's very easy to become unintentionally "airborne" (never mind that you're likely in a vacuum), e.g. when you're driving along at high speed and go over the lip of a hill.  That can be quite dangerous when it happens-- I would say that by far the most common cause of rover-destroying accidents in my own gameplay is when I take an unintentional "suborbital flight" and then end up smashed to pieces when I land.

When that happens-- when the rover loses contact with the surface-- your wheels are completely useless.  You're helpless.  The most important thing for surviving the inevitable landing is to make sure that the rover is correctly oriented, i.e. so that when it touches down, it does so with all wheels simultaneously, pointed perfectly along the surface.

And the only way to make sure of that is to use the reaction wheels while in flight to orient the rover.  Which you won't be able to do if you've set your reaction wheels to "SAS Only".

In short:  personally, I would strongly advise not setting reaction wheels to "SAS only".  Leave them fully functional, so that they can help you drive the rover.  The problem here isn't that the reaction wheel itself is messing things up.  Rather, the problem is that the game's rather silly default controls assignment happens to map the reaction-wheel controls onto the same keys as the rover-wheel controls.  That's the real problem, so the fix is to sort that out.

(And, just to be clear,  I'm not criticizing anyone here.  The above harangue notwithstanding, naturally every player has their own gameplay style, so I'm certainly not trying to tell you "you're doing it wrong" if restricting the reaction wheels is how you like to play.  Simply pointing out that there's another way that has some significant advantages, is all.)

[Foxster]

Even when you get the controls sorted out there is still a fair chance the thing will skip and bounce all over the place and end up upside down. 

The fixes for that are to build with a really low centre of mass and a wide wheel base. But for some real control and speed you want some downward force and I recommend an ion engine for that. 

Edited February 21, 2018 by Foxster

[Snark]

7 minutes ago, Foxster said:

The fixes for that are to be build with a really low centre of mass and a wide wheel base.

^ This, and also have some powerful reaction wheels on the rover.  In low gravity, they give complete control of the rover's orientation.  It stays nicely right-side up.  If a sudden bump throws it off-kilter, it can easily correct itself to whatever orientation you want.  And if, somehow, the rover does end up upside-down, it can simply flip itself right-side-up again.

[Marschig]

2 hours ago, Snark said:

Specifically because reaction wheels are incredibly helpful on a rover when you're on a low-gravity world.  If, for example, I want to turn the rover to the left, I don't have to rely on the wheels to do that-- I can use the reaction wheels to twist the rover to the left.  This becomes really important on low-gravity worlds because when gravity is low, everything becomes "slippery" (friction is less powerful), which means it's easy for wheels to "skid", and reaction torque can become much more useful for muscling the rover around.

Just set SAS to Prograde and Friction Control to 5. Rover becomes much more stable in turns and jumps.