Cannot add articulation to my robot

[xiaoqingyu0113]

I’m wondering why I cannot add articulation in my customized robot imported from Onshape.com?

[toni.sm]

Hi @xiaoqingyu0113

Have you looked inside the Physics submenu at [Context menu] > Add > Physics?

Also, a tip for creating articulations according to the documentation: Articulations must have a tree structure in terms of the rigid-body links and the joints between them

If it doesn’t work, can you share the .usd for inspection?

[xiaoqingyu0113]

Hello Toni. Thanks for your reply. I attached the usd file in the zip file.

[toni.sm]

Hi @xiaoqingyu0113

It seems to be your robot has already the Articulation Root…
However, the joint drives are not defined.

You can add drives as follow:

I recommend you check the Rigging Robots tutorial (particularly Add Joints, Drives, and Articulations section) for adding and configuring joint drives.

Also, check this post for hints:

Torque Control Model Parameter

The joint drive is a PD controller on the joint position and velocity target. The stiffness is the proportional gain to the position, and the damping is the Derivative gain on the position, and the proportional gain on the velocity target. For position target control set parameters for both Stiffness and Damping above zero. For a velocity control, set the stiffness to zero and damping to something above zero. For direct joint effort control, set both drive parameters to zero, and use the Adva…

[xiaoqingyu0113]

Thanks for your detailed reply! I really like it!