At the moment I'm working on the Stomp walk cycle, and I seem to be struggling with the knee portion of the assignment. I was wondering whether there are any tips and tricks that could be useful in preventing the knee from popping or making the legs look jerky?
Wayne gives some pretty complete responses to this here:
https://cgcookie.com/questions/6034-when-you-talk-about-trying-to-avoid-knee-popping-do-you-just-try-and-keep-the-knee-at-a-consistent-gradual-bend-during-the-pass-through#answer-8720
https://cgcookie.com/questions/12812-i-can-t-get-rid-of-this-knee-pop#answer-44082
https://cgcookie.com/questions/9656-how-to-deal-with-knee-pop-in-a-walk-cycle#answer-21055
It's tough because there are so many things that can cause this.
Some typical culprits:
Hips aren't rotating/translating correctly
Foot IK is stretching too far the frame before
Foot leaves/contacts the floor too early
Toe isn't rolling off the ground completely
It takes a lot of practice and developing your eye studying reference to identify what specifically needs to be done. Could you post a video of your cycle from the front and side? Getting another set of eyes on it could help identify what's going on faster.