How to (temporarily) parent limbs? (MoBu)

Rigging
#1

I have a crouching figure who supposed to rest his arms on his knees in a
certain take.

I set up a position constraint linking the WristEffector to the KneeEffector. If
I move the knee directly (with the gizmo) then the wrist does seem to be
glued onto it. Same thing happens if the ankle effector is moved thus
changing the position of the knee.

However if the knee is moved due to animation on the hips then the knee
and wrist start to slide on each other.

I also tried parenting an auxiliary effector of the wrist to the knee but a
similar thing happens: the aux box moves properly (glued) but the normal
wrist effector often slides off from it.

I replaced the position constraint with a parent constraint but the behavior
was the same.

The wrist effector has no animation whatsoever, only one key at frame 0
which sets its proper position.

Is it possible to fix this sliding?
(I can imagine that this kind of circular hierarchy is problematic: knee moves
hand, hand moves hips through IK, hips moves knee…)

EDIT: Clarified title.

#2

Wtf.

I restarted MoBu, loaded up the scene and now the position constraint
works as expected: the wrist is welded to the knee.

o_O

#3

Just a heads up, the circular issue is not a problem if you use AUX controls, just make sure you understand what the reach settings are doing when you add the AUX.

Mobu has a double solving system to deal with cycle errors and it can solve the loop correctly.

creat aux. parent the aux ctrl to the knee,
set the reach to the aux 100% for both T and R, make sure that you go back to the orig. wrist ctrl. and set its reach to 0 for T and R.

Otherwise you will end up with the skeleton 50/50 between the new AUX and the orig. control just like if you constrained it between two nodes.

Glad a restart fixed your issue though.

#4

Thanks Brad, I indeed forgot to zero out the original effector’s reach.

#5

There is a preference to do that upon creating an AUX ctrl. I forget to set it every time I install a new version…so It gets me a few times before I go, oh yeah duh!

#6

Good point. I’ve just added MoBu’s config dir to the daily autobackup:
C:\Users\Username\AppData\Local\Autodesk\MB2011x64\