He’s simply saying the foot is not centered under the ankle servo. In his leg the ankle is positioned farther back on the foot. Resembling the human foot. In most biped builds the ankle servo is centered over the foot in a symmetrical configuration. This means the walking may be as stable in forward or reverse.
That’s what I though, because in his photo I see the ankle servo more towards the heel of the foot where mine is in the center. I like the center config because the bot would be more stable from external forces from the front as well as the back as you suggested. If the bot bumps in to something from the front, it could easily fall backwards. It makes sense.
i will agree with having the ankle over the foot.
http://i531.photobucket.com/albums/dd355/innerbreed/100_2027.jpg
it helps with balance, as well as foot lift and land (performance).
as we are running ideas here and i have see take about converting the phoenix code for a biped, i feel i can add here.
i did this for my Iron Scout project.
http://i531.photobucket.com/albums/dd355/innerbreed/bps01.jpg
The red dots are for the true knee servo but i also show extra red dots here. the ankle dot is just a reverse of the knee.
This is a direct conversion and the code thinks its being used in a hexapod. iv kinda tricked the code.
also there are two sets of yellow dots…
while the hex walks forward the middle coxa moves front to back. i have taken this “movement” and used it to get the robot to sway “side to side.”
although is is showing the layout for the scout, it will still work for a humanoid robot too.
So thats why the phoenix code can be used with bipeds? I understand that it is very adaptable but I never really knew exactly why since my knowledge in inverse kinematics is still limited.
yes, i was looking at how the “control” input effects the “Function” output and realized that the code can be used for a biped. this then later went on to be the main structure for my upright style quadruped project.
anyway, one could really use Xans code in many different forms of robots. iv proved it works in bipeds and quadrupeds. with bipeds there is a fair bit of modifying to be done but its not that hard. Using the above pictures to see the relationship between servo is the trick.