View Full Version : Hand rig at a turning Steeringwheel

03 March 2005, 02:03 AM
hello there! - I would like to bring hands holding a steering wheel. While steering, the Hand still need to hold the Wheel. Do anybody know what kind of Constrainsets is needed? It seemīs not to be that trivial as is at seemed at the first glance...

thnx in advance for any help!

03 March 2005, 05:34 AM
You need parent constraints, but as you say, it can be tricky. This is how I do it:

First off, it'll be easiest if you're using IK hands, or can switch to IK at the point the hands grip the wheel.

Also may depend on your rig -- like if you have your IK hands following the torso, or anything like that. I'm going to assume that you don't b/c it's easier to explain that way.

Assuming that's the case, have an extra group node above each of the hand IK controllers, let's say called IKGRP. Create a locator at the origin called worldSpace, and at the first frame of your scene, parent constrain the IKGRP node to the worldSpace locator. Position the hands where you want them on the wheel at the frame you want them to be there, and constrain the IKGRP node to the wheel.

Now if you select the parent constraint itself, you'll see two things listed as W0 and W1, representing how much the constraint "listens" to each of the constraining objects.

Go back to the first frame of your scene. Set W0 to 1 and W1 to 0, and set a keyframe there. In the graph editor, Give the keyframes step tangents so there's no inbetweens.

Now go back to the frame where the hands grip the wheel. Now set W0 to 0 and W1 to 1 and key again.

If all goes well, you should find the hands will follow the wheel starting at the specified frame. The reason to use the extra parent group is that you're still free to key the IK hands themselves -- for instance, to slide along the wheel.

IF you find the hand jumping around in space when the constraints kick in, you'll need to play w/the keys on the hand, or you can always delete the constraint and try again. It makes more sense after you've tried it a few times.

Hope that made sense...

03 March 2005, 08:30 PM
@ ietra, thanx for support. Iīve done the way with the Parentconstrain. Not yet the way you explained - I will check that so far i have time then. what i did is, to group two Locators, under the Wheel and positioning them where the the Hand with the IKīs fits its best. then the got a Parentconstrain between the Locīs and the IKhandles - I didnt group the, and hope not to get a dissadvantage from that. Turning the Wheel, the hands doesnīt stay perpendicular to the Wheel axis, means - the hand will loose the "grip" while turning. I grouped the Wrist with it self that i have a handle to turn it back to a right position. All in all, i got several Parameters like wrist, th Locator at the Wheel, and the twist of the IK to be driven keyed by the Steeringweel. that fits at this time. hope the way has no other Consequences...

so long!

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03 March 2005, 08:30 PM
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