# Kinetic Rigging Question (Theo Jansen Style)

I'm trying to make kinetic mechanism, like link below.

Added armatures and IK constraints to the points that need to be anchored. Some bones need to be attached and move organically, but that doesn't currently work.

Thank you!

You can operate whole system adjusting geometry paramter [masterRot] of Obj [masterVar].

• Can you give us an example of how you want it to behave? Maybe a picture of the thing you're trying to rig? Commented Mar 21 at 3:13
• @Nathan thank you for reply. I want to create a wireframe that moves organically like the attached YouTube link. I would like to attach an image, but It would be more accurate to watch videocilp, please excuse me! Commented Mar 21 at 3:46
• Sorry, I didn't even notice the link. Hopefully the answer I provide below helps. Commented Mar 21 at 5:16

Let's start by marking some points:

D and G are static. We control by rotation of FG about G. We can drive that rotation from a custom value if you want, but the only masterRot I see is the input to a GN modifier. I guess we could drive it from the value of that input.

The structure isn't fully defined yet. To define it, we need to create a bone from F to E, as the structure in your linked video uses. We should also notice that ACD forms a triangle, where the angles can never change, so we don't really have to worry about AC.

FC and CD take part in an IK chain, targeting the free bone at D. (This point will remain static; I have parented to "root.") Both bones are IK locked in all but one axis. FC has inherit rotation disabled so that rotation of its parent, GF, won't flip it out when it rotates too far. DA is just parented to CD. (Remember, CDA is a triangle, it can never change angles.)

We can do the same with GE and ED now-- it's just a 2-chain IK, targeting the same, static IK target:

Again, locked in all axes, and DE doesn't inherit rotation.

Now we've defined the position of A and E, there's only one place that B can be:

AB and BE form a 2-chain IK, targeting the head of ED because that's convenient. Still locked in all but one axis, although that doesn't really matter; but here, we actually want AB to inherit rotation from its parent.

Now we can create the driver for the rotation of GF. I'm pointing all bones' Z axis at my camera, so we'll change it to a ZXY Euler and drive its Z rotation from masterRot:

You can map that however you'd like. As is, that's the rotation in radians.

One more thing to do. Let's fix those bones that aren't inheriting rotation so we can actually rotate the structure about. We'll reparent them to root, re-enable inherit rotation, then give them a copy location constraint, world->world, targeting their old parent's tail-- that is, acquiring the position of F. Any constraints we put on IK bones will be evaluated before the IK is evaluated.

And, I'll make a few copies with different master_rot inputs as proof that it's working:

• Really impressed by document and getting closer to the world of IK. Happy to learn from you master. Thank you😊 Commented Mar 21 at 5:38