SACH-SAWCH

OK those two were pretty much covered. The pelvis has a roll to play in these 6. With our center of mass held relatively stable by supple links and inertia in forward flight, the hips can ride up on one side if the other side, see-saw like, goes down. So, that goes on the list. But stow this one away for later as well; that pelvic movement can be made to amplify for other purposes. Bird's eye view, looking down:

The pelvis can also advance forward on one side (about 7 degrees) about a vertical axis also passing through the center of mass. Then it trails back to square to the direction of walking to then falls behind by 7 degrees as the other side, linked solidly, goes ahead by 7 degrees. That is a 14 degree vertical axis oscillation of the pelvis facing from 7 degrees toward the right to later be 7 degrees to the left and so on. This oscillation on a vertical axis was noted by Inman to provide longer step reach (length) than legs alone without any anti-gravity cost.