Target Bones Glitching

[Breadbox Productions]

I've made this rig, and applied target bones to his feet to keep them in place. However, when I move his feet or legs, his knees may go backward for a frame or two occasionally. It's really noticeable when rendered and I haven't been able to find help.

[voltus55]

I'm newbie, but, maybe, when the knee bend backward, you just simply select the calf bone. and drag the mouse while holding Shift in frame zero.
I forgot, select calf bone, select transform bone tool, and drag the mouse.

or, look what Victor do, here : viewtopic.php?f=13&t=26456

[jahnocli]

You could use bone constraints..

[Breadbox Productions]

Thanks Voltus. What you recommended seems to have done the trick.

[Greenlaw]

To expand:

This happens when the preferred angle for the IK is unclear or in the wrong angle for what you want. Normally, you want to put a slight bend in the joint in the setup frame to help the IK understand which way it should bend by default. Note that this preferred direction is not fixed and you can change it anytime during animation.

In other words, you don't need to be at frame 0. If the joint is bending the 'wrong' way at any frame, just select the Transform Bone tool and then click on and drag on the targeting bone to rotate it in the direction of the bend. This will change the angle of the bone so the IK can bend the joint in the direction you want. Don't over-drag it...it only needs to go far enough to change the direction of the bend.

Depending on what the character is doing, you may desire to switch the preferred angle multiple times throughout the animation. To do that, just drag the rotation towards the angle of the bend again (which would be the opposite direction of your the previous direction change.)