Bone not doing as it's told

Rigging
1

Hey guys and gals,

I’m having a problem in Max. I have a bone, that is position constrained and orientation constrained to a controller; foot bone on a creature, with the IK also linked to the controller.

As I rotate the controller about it’s local Z, as it reaches around -35, the foot bone suddenly snaps +5 in the foots Y axis, however the controller does not. The values I gave are rounded up btw.

I can’t for the life of me figure out why this is happening, but it is causing a big problem for the animator (who is just as dumbfounded) when she is trying to pose the character in exact positions, for animation blending.

Any help at all would be greatly appreciated, or even someone pointing me in the direction as to what could be causing the problem.

Thanks in advance.

2

Is that bone part of the IK chain?

3

Yes it is, it’s at the end of the chain, where the target is positioned.

4

It sounds like you might have a fight for control going on then. Hard to tell without seeing the file, but it sounds like you are trying to control the bone with IK and also the controller, but the controller is controlling the IK.

If your chain looks like this;
thigh
-calf
–calf_nub
–foot

and the Ik runs from thigh to calf_nub, then you don’t need the position constraint on the foot.

I would take the IK handle and position constrain it to the controller, then orientation constrain the foot to the controller. That should work.

5

Or do this regarding to this skeletal structure :

1-- thigh < “link” < calf < “link” < calf_nub <<< dont link FOOT Bone
2-- Now Run IK from Thigh to Calf_Nub
3-- Now Make Handle and Align it to Calf_Nub
4-- Link IK_Handle to the Handle

Now when you move the Handle, IK structure would flow it.

Method 1 :
5-- Only Link the Foot Bone to the Handle and then try to Limit the lenth of Ik to stick to floor.(Funny way)

Method 2 :
5-- You Can Position_Constraint the Foot Bone to the Calf_Nub
6-- Then Oreinataion_Constraint the Foot Bone to the Handle

Now it works Perfect, of course there are diffrent ways!

6

Thanks guys, I’ve realised my error now, thanks very much for the help.