[ASSETS] [OPEN SOURCE] Tanks, tracks and N-wheeled vehicles

[BoredEngineer]

@siverwolfe;470051

I’ve been following this thread for quite a while now, mainly because I find this type of developing to be incredibly interesting. Recently (today) I was able to get the materials I needed to try to get a tank of my own in there, because, who doesn’t like physics-based tanks?

But after setting it up, I found myself in need of a lot of help. So I’ll include them all here.

I followed Oldraven’s tutorial, and so far everything works as intended. the wheels collide, the splines are aligned, the suspension is hooked up, everything seemed to be fine visually. Except for one thing.

When running/simulating the game, the tracks seem to be linked to the suspension rather than the wheels. The tracks “bend” so that they are always directly below the suspension node-thingys. Now, that normally wouldn’t be a problem, since it would just be a matter of moving the nodes on the y-axis to make the tracks more straight. But the problem is that the road wheels are also connected to the suspension, so the act of moving the suspension nodes on the y-axis also moves the wheels.

I’m trying to port over a centurion, which is wider than the M113, so I have to move the suspension over to make the tracks act correctly, but by doing that, it ends up moving the wheels into the side skirts, no matter where I place the wheels. And it only shows when the game/simulation is running, and not in any of the editors. Any idea on why this happens?

Also, not really a problem, but more of a question, how do torque curves and gear ratios work here? I’ve been trying to get it to be somewhat accurate, but the only info I can get on the engine is it’s horsepower, max RPM, top speed, and number of gears. How can I use this with the ratios and torque curves?

In editor mode, position of the wheels relative to suspension is not really important, it’s more of the “reference” pose to place objects around. When you run the game, wheels will be re-oriented according to position and compression of suspension. If I remember correctly you need to place suspension handles horizontally in the position where you want you wheels to be during simulation. So first place the wheel where you want them to be and then move suspension handles into the same horizontal coordinates.
If you change vertical position of suspension then you need to make sure that you adjust Suspension Length parameter in suspension settings. When you change length of suspension or mass of the vehicle, suspension stiffness parameter have to be adjusted too. Longer suspension or higher mass - more stiffness.
In current setup suspension length is the “suspension travel distance” which sometimes can be found in technical specification of machines. This number is not the “default” distance between suspension handle and the wheel, it’s more of the distance at which suspension will have maximum force, or maximum suspension length. To get wheel positioned properly during simulation you need to adjust stiffness and length of suspension.

Only number of gears won’t help, you need actual gear ratios, which can be hard to find. Normally, I look first for the name of the gear box or transmission, then look for it’s technical or maintenance manual, if you lucky it will have some records about amount of gears and ratio of each gear. Just in case you don’t know it, when you see something called “final ratio” it’s not a gear but a multiplier for all gear ratios, so something like 4.3/3.2/2.1 with final ratio 2.0 actually means these ratios: 8.6/6.4/4.2
As this is a WW2 tank, information on it should be available, otherwise you can always “tune” ratios manually. Maybe you would be more lucky with finding gear box for different tank with similar engine and mass for example.

Regarding engine power. I need to check something first. Will reply on this one later.