Rovers are kinda funky

[Red Dwarf]

I have a looong drive ahead of me out at Eve. My rover is basically the same as all the other ones I've built, but it has a weird quirk thing. Sometimes, usually when driving downhill, the rover shakes. Speed doesn't seem terrible effected, but the shaking did cause a tire blowout. Any idea what's causing it, so I can avoid this in the future?

[Hobbes Novakoff]

Can you post a screenshot? One problem is that your rover might be made out of physicsless parts (Scott Manley did a video on the subject, I believe). This can cause quite a bit of weirdness within the game engine. Hope this helps.

[BagelRabbit]

If it's this type of shaking:

(pardon the shameless plug)

...then yes, the shaking is due to the craft being made of mostly massless parts.

Another possible cause is that of part-clipping... or an excess of SAS... it's really difficult to tell without screenshots or video.

My recommendation in the future is to do the five-minute test: drive the rover around on Kerbin for five minutes, and if it doesn't break, wobble, explode or fall on its side, it should be good for other planets or moons (except for the low-gravity ones, which are always a pain). I know it's not the best solution, and I might be able to come up with something better if I could see your design

-Upsilon

[CalculusWarrior]

What speeds are you generally hitting on your way downhill? And does the chassis of the rover shake, or just the wheels (or both?). If it's not a physicsless parts issue, you may just need to add struts, bracing the wheels to the main body of the rover. Eve's gravity is pretty punishing.

tl;dr: MOAR STRUTS

[GoSlash27]

It can also be the rover is simply too light for the suspension, which will cause the rover to jitter around on the surface at certain angles.

I never saw that actually *break* stuff, though.

Best,

-Slashy

[Red Dwarf]

I think slashy's got it. My rover is made of two material bays, a rover chasis, and two struts. It's pretty light. It isn't shaking like Bagelrabbit's, but it's pretty jittery. Also, something I hadn't noticed as of original post: during physics warp, the rover kinda glides to one side, even when the parking break is on. I'm pretty sure this isn't a problem that can be fixed by me, but I kinda wonder if anyone else has encountered it.

Also also, here's the rover.

The antenna on the bottom is the atmospheric probe. Dunno if the antenna's hitbox could be causing my jitter.

[hyperbolicj]

This seems to be a problem of design and there are a few things that could cause a problem of this kind.

A: Is the vehicle properly aligned. If the center of mass is not evenly distributed there will be at least one tire with additional pressure on it wanting it to swerve to a particular direction.

B: Are the wheels properly aligned. If the wheels are tilted, this is called camber and toe, then the performance will change. If you don't know what you're doing, usually for the worse.

C: Are there any components that are being dragged. This additional contact point on the ground could cause the vehicle to want to tilt, pivot, or rotate depending on its' position relative to the wheels.

D: Is there any part clipping that is causing the wheels or parts the wheels attach to, to become unstable

E: Is the wheel base that has drive, symmetric. For instance if your vehicle is front wheeled drive and you accidentally also left the back left wheel motor enabled the vehicle will gain speed on its' left side faster thus wanting it to turn to the right. The powered wheels on the right side will resist this and might in particularly bad designed to have the vehicle rock back and forth till it flips.

F: Going of the same line; Is the steering enabled properly and symmetrically. Generally when steering is enabled on all 4 wheels even when correctly can still cause issues in rocking the vehicle.

G: Is the weight of the vehicle appropriate for the wheels being used. Having too much weight on a suspension of a wheel will break it, but not having enough will cause the vehicle to roll easier.

Also this one hopefully never needs to apply to you but is good to keep in mind nonetheless. Keep your center of mass low. If you imagine the line from your center of mass to the contact point the wheel makes with the ground the more vertical that axis is, the easier the rover will be to topple. When you place the vehicle on an incline such that that axis is vertical or more relative to the force of gravity, Then you are beyond the point of return and the vehicle will tip unless you have sufficient torque to keep it upright.

[GoSlash27]

I think slashy's got it. My rover is made of two material bays, a rover chasis, and two struts. It's pretty light. It isn't shaking like Bagelrabbit's, but it's pretty jittery. Also, something I hadn't noticed as of original post: during physics warp, the rover kinda glides to one side, even when the parking break is on. I'm pretty sure this isn't a problem that can be fixed by me, but I kinda wonder if anyone else has encountered it.

Also also, here's the rover.

http://i.imgur.com/yoe9fTT.png

The antenna on the bottom is the atmospheric probe. Dunno if the antenna's hitbox could be causing my jitter.

I have encountered this many times.

Even a heavily- loaded rover can unload it's suspension if you catch an awkward slope. It's a bug in the game; local gravity doesn't seem to be dependant on inclination angles. I've seen stuff do a small angle transition and suddenly go from heavily loaded to light and skittering all over the place. I've even had rovers fall uphill.

There's no real fix for it, other than to take it slow, drive with light controls (caps lock), and disabling the front brakes/ rear steering.

Best,

-Slashy

[cantab]

I had this with my rover too. The wheel physics is a bit iffy, and they tend to go "light" when heading downhill, as though they're bumping off the surface. I just had to be mindful of it really, don't try and make a sharp turn when heading downhill at speed kind of thing.

Also, remember that you can put reverse drive when going forwards. That will slow you down more gently than the brakes.

[Pecan]

I think slashy's got it. My rover is made of two material bays, a rover chasis, and two struts. It's pretty light. It isn't shaking like Bagelrabbit's, but it's pretty jittery. Also, something I hadn't noticed as of original post: during physics warp, the rover kinda glides to one side, even when the parking break is on. I'm pretty sure this isn't a problem that can be fixed by me, but I kinda wonder if anyone else has encountered it.

Also also, here's the rover.

http://i.imgur.com/yoe9fTT.png

The antenna on the bottom is the atmospheric probe. Dunno if the antenna's hitbox could be causing my jitter.

Well now you've posted a picture the problem's obvious - SAS is on and the navball's pointing at the sky. Every little pitch and roll as you cross not-perfectly-level ground is going to have SAS fighting to put get you level again, and it's going to be getting it wrong. Add a probe-core oriented to the horizon properly and 'control from here'.

[Signo]

I experienced some shaking too even if I had the correct pointing end on the navball and I was driving in docking mode. To me it was an issue of angle snap. With "hex" angle snap the shaking is present.

[Hobbes Novakoff]

With "hex" angle snap the shaking is present.

"Hex" angle snap? Don't you mean symmetry? And on what? The probe core?

[Signo]

yes, I mean angle snap. I do not know the correct name for it (it might be something like "squared angle snap" opposite to "round angle snap") but the icon for it is hexagonal. When I used to place the wheels, 90% of the cases being the front ones, with the "squared or hex" angle snap I often experienced shakings even if everything looked perfect.

Going back to the SPH/VAB and placing the wheels in the same place but with the "round" angle snap was enough to solve the issue.

I hope I was clearer this time.

[Anquietas314]

yes, I mean angle snap. I do not know the correct name for it (it might be something like "squared angle snap" opposite to "round angle snap") but the icon for it is hexagonal.

The correct name is just "angle snap". The circle indicates "no angle snap".

Perhaps post a screenshot of the rover giving you issues?

[Signo]

The correct name is just "angle snap". The circle indicates "no angle snap".

Perhaps post a screenshot of the rover giving you issues?

It is not an issue of mine

Not anymore, at least.

[Anquietas314]

It is not an issue of mine

Not anymore, at least.

Perhaps, but if you knew exactly what the problem was, you could possibly avoid it in future without having to resort to not using angle snap

[Signo]

The problem was angle snap. And I found the same angle snap problem several times while trying to stick wheels to my rovers. W/o angle snap my rovers are fine, they go straight, they are even fun to drive. So, I'll stay without it, cause it is good for Jeb's health.

[Anquietas314]

http://i.imgur.com/l25fV1W.png

Actually I think the problem was trying to use angle snap on weirdly shaped parts, such as that Mk1 cockpit. Angle snap works best on very uniformly shaped parts (girders, fuel tanks, the like). Sometimes there's issues near the edges of long parts, but they tend to be very easy to spot, whereas the Mk1 cockpit might misalign the parts in very subtle ways (which would cause your jitter problem - misaligned wheels leads to bad things )

[Signo]

I experienced the same issue on wonderfully straight flt tanks.

[Anquietas314]

I experienced the same issue on wonderfully straight flt tanks.

Well, I've never had an issue with using angle snap for rover wheels as long as they're being stuck onto a suitable part. Maybe I just got lucky though.

[Docsprock]

I have a very similar issue with rover wheels. before 0.90, I was able to use angle-snap to align my wheels perfectly onto the ends of angled girders and modular girders. Ive had rovers with up to 28 perfectly aligned wheels.

Now, I cannot line up even 2 wheels. Regardless of what Ive tried, the wheels are always twisted on attachment and never line up. Makes me ragequit. Any suggestions would be welcome.

[Signo]

Well, I've never had an issue with using angle snap for rover wheels as long as they're being stuck onto a suitable part. Maybe I just got lucky though.

I experienced the shaking just with rugged wheels and often this is tied to the rover non going straight. While driving under 10/12 m/s the rover simply tends to go left or right, after 12/15 m/s one or both of the wheels start shaking like a kraken SAS attack is happening. I had a very close look at it several times, it looks like the wheel is pushed/pulled faster and faster left to right. The faster you go the worst the shaking. In the worst cases I managed to lose the wheels during the first 50m of the ride. And really, there is no apparent meaning for the shaking cause it is not a matter of "heavy load" or misplacement. Moreover, if it then works w/o angle snap, I think the issue should be angle snap itself. I might even be able to reproduce the issue at will. I'll check it.

[Anquietas314]

I experienced the shaking just with rugged wheels and often this is tied to the rover non going straight.

I pretty much exclusively use those wheels; I've still never had an issue with them that wasn't just a design flaw (wheels a few degrees off, etc). Of course, I tend not to send rovers to eve, mainly because I don't send Kerbals there (the lag of a return ship would kill my poor old computer); I generally build the "manned" variety so I can fix the wheels if they get broken due to my reckless driving , so it's possible the issue is specifically with eve's high surface gravity.

[Signo]

I tend not to send rovers to eve, mainly because I don't send Kerbals there (the lag of a return ship would kill my poor old computer); I generally build the "manned" variety so I can fix the wheels if they get broken due to my reckless driving , so it's possible the issue is specifically with eve's high surface gravity.

I experienced the issue mainly @KSC, usually I do not send to Eve flawed rovers.

[Anquietas314]

I experienced the issue mainly @KSC, usually I do not send to Eve flawed rovers.

Then yeah I've never had that issue :/ Most of my rovers work just fine driving around KSC, the main exceptions being ones that don't handle turns well or flip when you hit the brakes or similar issues. No jitters.