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Hi everyone I'm still a beginner at blender and I'm trying to make a simple wheel rotation using empty and drivers, the wheel rotates fine when I move the empty on local Y-axis but the problem is when I try to turn the empty on local Z-axis the wheel also rotates in place, this is not what I want and I don't know what's wrong, anybody has a solution? thank you very much Wheel forward and backward

Wheel turning

Haryo Murti
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This set-up is only good if you are going in a straight line. You have not said anything about parenting or driver settings. By looking at your gifs, I can assume you have the wheel parented to the Empty, and your driving the wheels 'X' rotation with the Emptys 'Y' location in 'Local' space, Am I correct so far ?? Even if you change the drivers space to 'World' or 'Transform' - you will still have a 'Coordinance' issue. So then you start thinking , I will use an armature bone(s) - well you will run into the same 'Coordinance' issue again. This issue has been highly debated over at BA for many years, we refer to it as 'the tank track issue', it is a shame that something so basic is so troublesome. So clockmender wrote an animation node to overcome this issue, but if A/N is not your thing, then this is my solution I use; I create 3 actions for the wheel, (1) START (2) TRAVEL (3) STOP -- You can combine these into one action, but I find this way more flexible. You assemble those actions in the NLA, then all you have to worry about is animating the steering. Hope this helps in some way.

AJCDFIN
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  • Hey thank you for the answer! Yes your assumption is correct I parrented the wheel to arrow empty > then I parrented the arrow empty to cube empty. I actually didn't expect this to be a complicated issue . I have animation node but i havent try it yet. I'll try the NLA editor tommorow. Thank you again for the answer! – Haryo Murti Apr 09 '20 at 20:00
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    Please provide examples for your answer. As it is it is not helpful to the community – Noob Cat Dec 23 '22 at 15:16
  • It would be great if you had a minimal toy example of the 3-state solution to show.. – Robin Betts Dec 23 '22 at 16:52
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I currently use 2 transform constraints for wheel rotation. One mapping x location to my desired wheel rotation and one mapping y location to the same rotation.

Either that or I keyframe an empty to move along one axis then map that empty location to the wheel's rotation and its curve offset(when using follow path). Add an expression to the driver to convert distance into rotation using the diameter of your wheel.

GTS
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