pivot point of a group

[Anonymous]

It's probably a dumb question as I'm new to rigging, but I got stuck at this problem,  just couldn't figure out a solution. 

I have this fore leg from a feline set up in the scene. Fairly simple as you can see in the screenshot. Several joints, corresponding IKs and a foot control. I need to set up rotation at the Wrist_Pivot  group, and the pivot point should always be on the wrist joint as you can see as below. 

But since it's the child of foot_Ctrl, whenever I move the control, the pivot point shifts from that joint as you can see as below. 

I understand it is the way parent/child works, but this is not what I need. Any advice/workaround?

Here is the link of the file if you'd like to have a play:

ForeLeg_Rig.mb - Maya2016 file.

I'm dying to know how to do it!! Appreciate it!!

[gautham.chandran47]

Why don't you add the IK handle to the Wrist joint ?

[Anonymous]

Do you mind elaborating a bit? Add which IK handle to the wrist joint?

[gautham.chandran47]

Share a .ma file, and I'll explain it to you.

[Anonymous]

Here it is! I'd appreciate it very much!!

ForeLeg_Rig.ma

[gautham.chandran47]

Well, that wasn't easy .... burned my brains out 

 But found a way around it. Add a locator and parent it to the wrist joint to track its position.. Then create a control curve and group it and parent constrain it. Then it will be in exact place.. Then connect the attributes. You may have to inverse the values by using a "multiple divide node".

[Anonymous]

Wow!!!! Very much appreciate it! 

Still testing it, and for some reason it seems to rotate weirdly when the foot ctrl is at a higher position like at frame 15, but it could be my joint's local rotate axes. I'll remake it with correct and clean joint chain and test it out again, but before that, I wonder why connect the rotation X of the Wrist_Pivot _Ctrl to the rotation Y of the Wrist Pivot group? And similarly, the other two axes connection between the two confuse me too.

[gautham.chandran47]

That's because the orientation of the "wrist pivot ctrl group" is different from the controller. That's nothing to be concerned about. Just check where they are rotating on each axis and connect to the appropriate axis.