Replied to here:
http://vizworkshop.com/articles/walk..._app#comment-3
Answer:
I could not reproduce the problem. I made your changes to UserAvatar.py and movement is smooth. Perhaps if you post your UserAvatar.py I can see your problem. The one you posted does not have your change to the "updatePostPhysics" method.
The problem could be because your moving the physics shape/box inside of another physics object, the tankmaze floor, with your updatePostPhysics method. This could be generating some strong "repelling" forces and make your movement jerky/weird. Hold the feet Y value at 1 or above to fix.
Also, the corners of collideBox cause some funky jerks when running into the hedra shape. Change back to smooth object like capsule or sphere to fix.