I’m trying to use the “Lula Robot Description Editor” function to start the kinematics process on a customized robot. The robot was created in Onshape and placed the joints and imported into IsaacSim, within Isaac I added physics and now I can move the joints separately. When I try to use this function the following error appears
“2023-10-26 13:11:39 [Error] [omni.ui.python] IndexError: list index out of range”
“2023-10-26 13:11:39 [Error] [omni.ui.python] At:”
“2023-10-26 13:11:39 [Error] [omni.ui.python] c:\omniverse\library\isaac_sim-2022.2.1\exts\omni.isaac.robot_description_editor\omni\isaac\robot_description_editor\extension. py(273): _on_select_sphere_gen_link”
“2023-10-26 13:11:39 [Error] [omni.ui.python] c:\omniverse\library\isaac_sim-2022.2.1\exts\omni.isaac.robot_description_editor\omni\isaac\robot_description_editor\extension. py(319): _refresh_sphere_gen_link_combobox”
How can I solve this? Would it be a problem due to being imported from Onshape or some limitation that I’m not aware of? I created a simple robot using blocks and joints with revolution joints and this LULA function worked without problems.
The Lula Robot Description Editor makes a whole lot of assumptions and is very finicky. You need to make sure the top-level xform has an articulation root. Below it, each child xform becomes a link. Each child should have a rigid body. The articulation root should not have a rigid body. I think I gave the children Mass as well, don’t remember if that was necessary or not.
The second Xform (RX160L_HB_WS) is an articulation root and the links below it are rigid bodies. I can’t understand the problem with this hierarchy and I can’t change anything because everything is blocked. (Imported from Onshape). Would you have any tips?
Note: I still have difficulty understanding these blue and orange arrows in xform
Yeah, I suffered through this. The arrows show references. If you do “File → Save Flattened As” and then load the created file you’ll be able to clean up the hierarchy. The flattened file still has references, but they are local references and you can move things around. I usually make so there are no references, but this may not be needed.
Thanks! It worked, but besides that (it may seem confusing) it created duplicate references in my hierarchy and even then LULA Robot didn’t work, I had to delete all the extra references after “Save Flarrened As” and return everything with Ctrl Z, like this my solids were unlocked and LULA Robot worked. I don’t know if it’s correct, but for now it will serve as a study. I appreciate the help!
Yeah, the flattened as creates lots of internal references. I manually delete the reference from the link prim, and then move over the things from the referentee to the link prim. It’s a giant pain in the ass.
