How is the redundancy of the 7th joint handled?

[LAKY911]

Hi,

First of all, thank you for the great work on this stack—it's been extremely helpful for my research.

I'm currently working on my master's thesis focused on visual servoing with the iiwa, using your lbr_fri_ros2_stack. The stack works well for my experiments so far, and I am using MoveIt Servo for real-time Cartesian control of the end-effector.

My current MoveIt2 configuration uses the default KDL kinematics plugin, but I noticed that MoveIt2 now also supports bio_ik, which seems to offer better support for redundancy resolution.

I had a few questions regarding this:

1. How is the redundancy of the 7th joint currently handled in the provided MoveIt configuration?
2. Is there any internal null-space optimization, or is the 7th joint simply kept constant?
3. Would switching to bio_ik be a recommended way to better utilize the 7 DOF capabilities of the LBR iiwa?
4. Are there any known limitations or integration issues when using bio_ik with your stack?

I believe this information could be valuable not only for my work, but also for others, as the LBR iiwa is widely used in academic research and theses.

Thank you in advance for your time and insight!

Best regards,
Lukas
CTU in Prague

[mhubii]

Hi @LAKY911, wow, these are very in depth questions. Personally, I haven't used the bio_ik plugin. The current configurations are just the MoveIt defaults. Please if you could share any learnings, that would be great!