OK folks.... you need to download this one and enlarge it to see what's going on. I took the 22 stances that equal one cycle of just straight line walking on a level surface. I put copies of just the pistons below. In each piston I placed a "measurement column." These measurement columns start out grouped by stance. They need to be grouped by piston type (done using copy, paste, and layers). This grouping allows one to "look" at just one piston motion over the 22 stances (example: the left foot eversion piston). This is shown above. Example: if you make visible only the layer named "eversion left," then you will see all 22 measurements of only the left foot eversion-inversion piston. For any piston you choose, sequentially subtract that piston's measurements to get net piston motion for that piston over the 22 stance cycle. Add all these up and you know how much fluid moved around. And, of course, I used texture maps and color to prevent getting confused. Prety cool, huh ? I haven't done the subtractions yet, more to come. To design a pump (the "heart" in the robot's chest cavity), you must first know how much fluid to pump. so there!