After animating a character, I noticed that his feet would vibrate/jiggle in place whenever I moved his leg or shin.  It would take too long to move the foot back into place after each frame, so I tried to add a constrain modifier to the foot.  Unfortunately, the mesh is skinned to a biped, and I can’t add any constraint to the biped.  Is there any way I can add a constraint to a biped, or do I have to find another way to keep his feet in one place?

You’re not looking for a constraint, you’re looking for inverse kinematics (or IK). You need to set an ik key for the leg, and the foot will stay planted. It’s in the key info rollout (if memory serves). The button’s called “Set planted key”.

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James Kelly
fo co mo so

Thank you, that mostly solves my problem.  Just one last question, do I have to add all of my keyframes from that key info rollout?  Once I added a keyframe with the key button next to auto key and set key and it altered the foot like I never set the planted key.  Adding the free key or sliding key seemed to work (I’ll find out the difference later). Do I have to set a free/sliding key for his arms or head even though they have nothing to do with his legs.  Or should I be fine with normal keyframes and such?  I just don’t want to find out later that I was supposed to do the opposite of what I was doing.  And again, thanks for the help.  I couldn’t find that solution ANYWHERE.  All the other solutions involved bones and not bipeds…

I’d recommend reading the entire section on character studio in the help. Everything you asked is covered there. Especially in the “freeform and IK” section.

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James Kelly
fo co mo so

I shall do that then.  Thanks for the help.