Hello Sébastien,
First very happy that you’re going to continue and improve my work.
Indeed, I did the calculation of the inverse kinematics only using 3 motors and I fixed “r_arm_z” at -90° with this way I only explored the space of my interest ( Cinematique Inverse bras de Poppy), the wrist motor and gripper don’t change the IK, I controlled these ones separately.
If your question is, which motors are effectively used in the Inverse Kinematics? I only use 3 motors.
q0 > r_shoulder_y
q1 > r_shoulder_x
q2 > r_elbow_y
Then the motors XL-320 are coupled in the IK using linear regression, and the motor “r_arm_z” is always locked at -90°.
Well I only made this arrangement because I wanted to prove my hypothesis, but then another internship student worked exclusively in the inverse kinematics with a better performance.
I made one software entirely in python to control the arm ( https://github.com/joelortizsosa/Inverse-Kinematic-Python/tree/master/Software/Direct_connection) you can add the new IK library and it will work much better.
Well, the Monday 8 I will go to INRIA and we can speak a little more.
@+