request - inertia, dynamics, & transmission elements in gp4 URDF for use in ROS/Gazebo physics simulation

[adamlouis]

Hi!

I am trying to simulate the GP4 arm in Gazebo + ROS tools.

The GP4 URDF in this repo contains:

• geometry
• collisions
• joint relationships

but does not have

• <inertia> tags on links
• <dynamics> tags on joints
• top-level <transmission> tags for control

For context, see:

• Gazebo URDF requirements: https://gazebosim.org/tutorials/?tut=ros_urdf
• Gazebo Transmission & Control requirements: http://gazebosim.org/tutorials/?tut=ros_control
• URDF transmission docs: https://wiki.ros.org/urdf/XML/Transmission
• URDF link docs: https://wiki.ros.org/urdf/XML/link
• URDF joint docs: https://wiki.ros.org/urdf/XML/joint

I noticed that the sia10d URDF file in this repo does have <inertia> tags.

But no URDF file in this repo has <dynamics> or <transmission> tags.

I am working concurrently with a different arm from a different manufacturer -- here's an example of a URDF file that contains all of those fields: <inertia>, <dynamics>, <transmission>.

So, any chance you can add <inertia>, <dynamics>, or <transmission> to the GP4 URDF here?

[gavanderhoorn]

I'd refer you to two recent discussions about the same topic: #322 and #416.

From what I've understood, it's unlikely we'll add them.

The ones in the SIA10D model are approximations (and most likely bad ones).

I'll leave this open and wait for confirmation from @EricMarcil, but from the previous two issues I expect my answer to be correct.

[adamlouis]

Thank you @gavanderhoorn!

I missed those prior discussions in my search. I suspect you are correct too.

I have reached out to @EricMarcil & our Yaskawa representatives to move forward.

Thanks for pointing me in the right direction!

After I connect with Eric & Yaskawa, I can add a note to the README for the next person who encounters this.

[EricMarcil]

That is correct. The current policy to get more detailled information about a robot dynamic properties is to put in place a none disclosure agreement (NDA) with your local Yaskawa representative. We will then transfer the requested information directly to the requester and ask that they do not get posted publicly.