Eve Rover Help

[ScottyDoesKnow]

I'm trying to make a very simple Eve rover, just for transporting one kerbal. I decided to use the sturdiest wheels that aren't the giant ones, but it flips incredibly easily on turns. I also tried unsuccessfully to throw some legs on in different places to flip it back over, as well as disabling the motors on two of the wheels.

So just looking for general suggestions on the rover. Should I use different wheels? A different design? Examples? Here's a picture of it right now (everything docking port and up won't be there).

Edited March 15, 2014 by ScottyDoesKnow

[Behemoose]

First and foremost, if you're the same guy, I LOVED your Minecraft mods.

My experience with rovers is that no matter where they are, they handle like there's very little gravity. They love to bounce around and flip over. That said, you can make them more forgiving.

You could try putting the wheels at the end of modular girder segments to widen the vehicle and lower the center of gravity. That will make it slightly less tip-happy. Something like what I've shown here, but not as ugly.

Edited March 15, 2014 by Behemoose

[Vanamonde]

Low and wide. That is the mantra for landers, and even more so for rovers. Heck, even this

can flip if I drive it incautiously. The lower and the wider the better.

[Dispatcher]

You could make a stripped down version of this:

Hmmm. Image not displaying in my browser. Edit: fixed.

As the others wrote, shorter and wider is good. If you go with more than 4 wheels, lock the steering on the middle wheels.

Edited March 16, 2014 by Dispatcher

[Red Iron Crown]

Disabling the reaction wheels in your probe core and lander can will help, too.

[Pecan]

Try to have your command pod/remote control probe core pointing forward, not at the sky (as it is in Behemoose's picture). SAS and the built-in pod torque will be much more stable when pointing at the horizon but are still usually better turned off.

[cantab]

Maybe try ditching the rovemate and just fix the wheels to the side of the lander can, possibly with the aid of girders/struts/i-beams. The original design looks top-heavy.

[Kasuha]

1/ Decouple your rover controls from your direction controls. Set rover controls to numpad (recommended) or at least HNIJKL like for RCS. Use the rover with SAS turned ON to keep the direction.

2/ Add reaction wheels. That will allow to keep your rover straight or turn it back in case it turns over.

3/ Low and wide is good idea but if you happen to turn it upside down, then it's pretty hard to turn it back. With SAS control you don't really need your rover to be that wide.

4/ Use parts with high crash tolerance as bumpers

Edit: I tested your rover with a small change - added reaction wheel and four NUKs - and it worked like charm.

Edited March 15, 2014 by Kasuha

[Claw]

I've been working more on rovers myself and find them a little frustrating. It seems they are either really wide and flat to aid stability, or I make something interesting looking and have to drive like I'm about to lose my license.

Anyway, I have found a lot of what Kasuha says has helped.

- My controls were already decoupled, since I put reaction wheel rotations on my num pad, and left the rover forward/backward/left/right on WASD. I didn't set it up that way specifically for rovers, but it certainly helps.

- The reason why the above helps me is because, I too, found that adding reaction wheels can help. I find that when I'm driving the rover at high speed and turn just a little too sharply, I can recover it by reaction wheel rotations with my separate keys. If I had disabled the reaction wheels completely, this would not be the case. Also, I have recovered a few rovers with the mighty strength of SAS.

- I also sometimes add extra cubic struts around critical components, just so there's a crash cage/crumple zone.

If your rover flips just by turning with no speed, it's probably your controls set up.

If it happens while you're moving, then the CoM is probably too high for the wheel base (as others have said). I've also compensated a little for this by turning on precise controls (Caps Lock).

[ScottyDoesKnow]

First and foremost, if you're the same guy, I LOVED your Minecraft mods.

My experience with rovers is that no matter where they are, they handle like there's very little gravity. They love to bounce around and flip over. That said, you can make them more forgiving.

You could try putting the wheels at the end of modular girder segments to widen the vehicle and lower the center of gravity. That will make it slightly less tip-happy. Something like what I've shown here, but not as ugly.

http://i275.photobucket.com/albums/jj307/srook2/screenshot40.png

That is me, thanks! Ya, my problem here is I'm trying to keep it as compact as possible to fit my lander. So I've been leaning more towards a self-righting system instead. I have one that sometimes works with lander legs, but half the time the legs just clip through the ground when they extend.

1/ Decouple your rover controls from your direction controls. Set rover controls to numpad (recommended) or at least HNIJKL like for RCS. Use the rover with SAS turned ON to keep the direction.

2/ Add reaction wheels. That will allow to keep your rover straight or turn it back in case it turns over.

3/ Low and wide is good idea but if you happen to turn it upside down, then it's pretty hard to turn it back. With SAS control you don't really need your rover to be that wide.

4/ Use parts with high crash tolerance as bumpers

Edit: I tested your rover with a small change - added reaction wheel and four NUKs - and it worked like charm.

My rover controls are on the arrow keys, and there are 4 NUKs hidden inside the body currently. I've tried adding a reaction wheel, but I wish there was a weaker one I could use. The standard one is just so ridiculously powerful it feels wrong, and it drives so strangely with SAS on (like when you start going downhill and the rover stays perfectly horizontal).

For now I think I'll just keep testing my self righting system and see if I can make something work.

[ScottyDoesKnow]

Got the self righting system working well enough. It requires a kerbal to run into it for the final push but that's fine. Top speed over 20m/s, drives fine on 4x acceleration as long as you don't need a perfectly straight line. And all the corners are wheels or landing legs so it should be pretty strong. Thanks for the advice guys.

Javascript is disabled. View full album

It also fits perfectly between the launcher and return tug, didn't even have to move the struts.

[Kasuha]

I've tried adding a reaction wheel, but I wish there was a weaker one I could use. The standard one is just so ridiculously powerful it feels wrong, and it drives so strangely with SAS on (like when you start going downhill and the rover stays perfectly horizontal).

First of all congratulations to making your design work. I kinda wonder how your self-righting sets the rover straight if it turns completely upside down but I believe it works for you (otherwise I'd expect you to not be so happy with it).

I admit the torque is kinda strong for such small thing but it is strong enough to turn it around without any movable parts. And if it sits wrong on the surface, I just hold F for a short while to let it settle down. I found torque invaluable for keeping the rover straight in sharp turns (I use common action of rover-right, D and E to turn on as small diameter as possible and it is very effective). I found it also very useful in low gravity environments such as on Minmus where many people complain about rovers being useless.

[ScottyDoesKnow]

First of all congratulations to making your design work. I kinda wonder how your self-righting sets the rover straight if it turns completely upside down but I believe it works for you (otherwise I'd expect you to not be so happy with it).

I admit the torque is kinda strong for such small thing but it is strong enough to turn it around without any movable parts. And if it sits wrong on the surface, I just hold F for a short while to let it settle down. I found torque invaluable for keeping the rover straight in sharp turns (I use common action of rover-right, D and E to turn on as small diameter as possible and it is very effective). I found it also very useful in low gravity environments such as on Minmus where many people complain about rovers being useless.

Oh I understand that a reaction wheel is probably the easiest and best solution here, it just feels cheaty to me when I can breakdance my rover around with no moving parts (and this coming from the guy who hid 4 NUKs in the body). Here's the self-righting mechanism:

Edited March 15, 2014 by ScottyDoesKnow

[Claw]

I have also found that holding the rover turn and the SAS roll (into the turn) helps keep it planted firmly.

If the reaction wheel is too much torque for your taste, you can add more probe cores. They come in weaker torque varieties and you can mix/match amounts less than 20.

[ScottyDoesKnow]

I have also found that holding the rover turn and the SAS roll (into the turn) helps keep it planted firmly.

If the reaction wheel is too much torque for your taste, you can add more probe cores. They come in weaker torque varieties and you can mix/match amounts less than 20.

With only one probe core I don't think the SAS roll makes much difference in this case. I tried adding 4 more tiny probe cores in the middle for a total of 2.5 but it still wasn't even enough to tip it over from its standing position, so I said screw it.

[Kasuha]

Here's the self-righting mechanism:

That's very nice! I remember I was trying to invent something similar for my rover (quite a bit bigger though) and I failed miserably. And then I succeeded with just one torque wheel. It would not probably turn it on Eve though.

If the reaction wheel is too much torque for your taste, you can add more probe cores. They come in weaker torque varieties and you can mix/match amounts less than 20.

There's large gap between probe core torque (1.5 for the 2.5 m one, 0.3 for the first successor) and reaction wheel torque (20).

[Claw]

With only one probe core I don't think the SAS roll makes much difference in this case. I tried adding 4 more tiny probe cores in the middle for a total of 2.5 but it still wasn't even enough to tip it over from its standing position, so I said screw it.

There's large gap between probe core torque (1.5 for the 2.5 m one, 0.3 for the first successor) and reaction wheel torque (20).

Oh yeah. Sorry. I wasn't thinking in terms of flipping the vehicle over. More of adding just a bit of torque for driving. For the smaller rovers I've been playing with, I found that even the torque in the smallest probe core is enough to prevent my vehicle from flipping over during a turn (when you find yourself up 90 degrees on two wheels), but that's a different story than flipping it off it's back.