Methods for Rotating a Wheel Using Xpresso

Offering a look behind some of the math of having a wheel rotate with proper ground contact, CreativMotion’s Cole Wilson shows how to drive (so to speak) the animation with Xpresso.

If you need to animate a wheel rotating, lets say from a car or any other vehicle, having it rigged in such a way that the wheel gets automatically driven is pretty essential. There are wheel setups of varying degrees of difficulty, depending on what you need the animation to do in the end.

In this tutorial we will be looking at the maths behind rotating a wheelCole Wilson – CreativMotion

For example, having a wheel orate while a car is moving back an forth is relatively simple. What happens when you turn the car? That set up becomes a little more complex. In fact to be truly realistic, one wheel in a turn moves at a different rate than the other.

Xpresso to the Rescue

Here, Cole shows who to use a position controller to begin the wheel rig. He shows how to work out the ever important circumference of the wheel to base the math on. Then he continues to show how to drive the wheel based on distance rather than an axis position.

This is done with a range of Nodes in Xpresso, using the Vector to Reals Node, the Distance Node, and the Range Mapper Node to conform and wire a range of values. Cole also takes a look at the bounding box node in Xpresso, showing how it can be used to automatically feed the value of the diameter into the existing Xpress setup.