Rotation of wheels/treads over distance

[boxershorts]

I'm very new with Maya 3.0 and was wondering if anyone had any helpful suggestions or know of any online tutorials covering the above topic.

Specifically, what's the easiest ways to animate the rotation of a wheel or tank treads in relation to the distance traveled? What if the wheel turns? What about a tank rotating in position (right track forward & left track reverse)?

Thanks in advance for the help.

[neil-johnson]

the easiest way is to just keyframe the wheel at different frames and set a rotation amount between the keyframes. Say like have it rotate like 720degrees on that axis.

You can also in MEL do a simple code to have the wheel turn when the vehicle is moving or object. Its something like

if the car moves in this direction then the wheels move in this direction and u can set it multiplied to rotate exponentially faster.

Not sure about tank treads since that really isnt rotating on an exis its an irregular movement.

[maos52]

If i'm not mistaken you would do R x PI (3.14.......) and divide the distance to be traveled trough the outcome of that multiplication... This would give a result about what the distance would be to do 360 degree-turn...I think...don't pin me to it, I'm terrible at math but pretty good fantasizing about it!
I'd go to a toy-store and buy a toytank with big rubber-tracks to find out how that would work...
Hope this helps any, Maos.

[djfluid]

search the Mel section on this site......pretty sure there is an expression for what u want...dunno about the tank thing

[boxershorts]

I found a geometry formula that might work, but I was wondering if there were any experts out there who could help (I'm not a math wiz) translate this to an expression for animation. I want the rotation to be accurate so that the wheels don't appear to slip on the surface. See if this makes sence to anyone -

(translateZ * 360) / (pi * diameter) = rotateX

But this brings up another problem ... how do I measure the diameter of the wheel? I'm still looking for info on the tank tracks. My guess is that the treads would animate on a path(?) More help please??

I'm animating a group of different type of robots playing a game of soccer. Some of the robots have wheels others have tank treads. Thanks.

Edited by Kirt on 04/27/01 10:05:45 AM.

[maos52]

u huh, that's what I meant ,(bout the formulah
Did you do a search on 'tank' or 'tracks' or both? Coz I'm really sure about a similar post not to long ago and they solved it I think by using a free online script...

You can measure with the tools made for measuring... RTF

If you didn't delete the history you can still find the radius...

Have a nice day, Maos.

[torran]

The diameter of the weel is simply the scale in that direction, I just used the formula in a MEL script and it worked great but only with translation in one direction is there anyone that could tell me how to make the formula for multiple directions?

[torran]

global float $pi =3.1415;
wheel.rotateY =((sqrt(((bilen.translateZ)(car.translateZ))+((car.translateX)(car.translateX))))360)/(wheel.scaleZ($pi*2));

This is the script I wrote to have the right rotation and still be able to translate the car in XZ-plane, it works perfect!!! The car is a group-node of the whole car and the wheel is one of the wheels, simple as that..............

Torran..........

[boxershorts]

OK ... explain what "bilen.translateZ" is refering to. The rest of the formula makes some sense to me - although I haven't tried it yet.

Thanks.

[torran]

sorry bilen=car, im from Sweden so if you want to learn swedish bilen means car..............

Torran......................

[boxershorts]

OK ... this works pretty good compared to what I had before but there are still a few problems that may have been overlooked (or I'm doing something wrong still). Using your formula the wheel rotates properly as long as the car stays on the X or Z axis, OR only turns in one direction. I created a path for the car to follow and if the car changes direction (makes a 'S' turn or 'U' turn) the wheel stops rotating properly. In either case the wheel will either stop rotating or rotate in the opposite direction.

I have searched this board for other solutions and have come across several people who asked a simular question, but no one has been able to offer a solution yet that I can get to work the way that I want it to.

Thanks for the help so far ... but I need more. Anyone with a different solution?