I am completely new to MotionBuilder and have been asked to help clean an animation that is already close to finished. However, I am attempting to get my character to grip a hammer. The parent child constrain has alread been set up and works correctly but I cannot get the character to make a proper closed grip.
The knuckle joint on the character appears to be fixed or frozen and does not move at all when i manipulate the fingers in the controls tab of character tools. I have attached a image of how what the problem looks like.
It's 5 years later and this is still unanswered, not even a suggestion. I am new to motionbuilder and having the same issue. If I figure it out I will post a solution for the next poor soul that has this problem.
Just in case, check as well you keying mode, if you are in "Selection" keying mode, you can't rotate your control rig IK effectors but only rotate FK controllers if your "IK Blend R" % is set to 0. You have to be in "Body part" or "Full Body" to fully use IK Effectors.
In your screen the fingers are out of proportion. Your fingers looks too thin and too long compare to your palm. Second knuckles (middle phalanx) are way too long compare to third knuckles (proximal phalanx) .
Your joints looks misplaced. They look to be in the center of the finger section instead of being at 1/3 from the top of the finger section. The inside of the finger (palm side) is where you find most of the fat, finger bones are closer to the top part of fingers section.
So this is super late, but maybe this will help someone else looking for an answer to this question.
In the Navigator window, go to Characters. Double click on the character name (ex: P01: Character).
This opens up the character settings. Expand Solvings, and check the box for finger solving.
Hopefully this helps. Took me a minute to figure out where to go for finger solving.