Hi Ron,
The new animation course is on the way, however, it is a revamp of the “Fundamentals of Animation”. Which is the beginner stuff.
So the new course doesn’t cover character animation or knee popping.
Like @phoenix4690 mentioned, popping is a problem with the IK system. It has a mathematical cause where the acceleration of the joint approaches infinity. (see a tan curve – as in a sin and cos curve. The tangent wave has a discontinuity where it shoots off to infinity).
You can combat it by using a soft IK set up, where it dampens the speed of the knee joint so it never actually reaches the goal. But this has a its own set of different issues and it only solves half the problem (bent to straight, not straight to bent).
Sadly, the only real solution is improve your body mechanics and then tweak the knee with the bend controller as a very last resort.
I posit that you worked hard and improved your skills to a certain level where you could actually see the issue (most people can’t) and didn’t quite get to the point of resolution. I guess this is one of the down sides of improving your skills, the better you get, the more you see where you need to improve.
But don’t let a knee pop stop you from animating!
