Asking about the dynamics of the robot

[duckykao]

Hi,
I am trying to build only the lower limbs of the OP3 robot, and I have to build a center of mass of each leg joint relative to the leg hip, like the table below with respect to the robot figure. However, after looking up the description and the code in "op3_kinematics_dynamics.cpp", I still have no clue on how to build such table. My biggest question is what does "relative_position_ " represent ? What position does it relative to ? And for "center_of_mass_ ", what does the location of represent? Does it mean the relative location to some position ? If that is the meaning, then what position does it relative to?

Please let me know if anyone have any clue.
Thanks a lot.

[ROBOTIS-Will]

Hi @duckykao
The relative_position represents the pose respect to the joint of the parent link.
The center of mass represents the center of mass of each link.

Orange boxes : links
Blue dots : Reference points of the link
Orange dots : Center of mass
Red lines : relative positions