Hi,
I have a problem using the URDF importer in the latest release of Isaac Sim. When I use the URDF importer in Isaac Sim 2023.1.1, there is a problem that the loaded robot is not recognized as an Articulation Robot, and connecting it to ROS via omnigraph does not work. Only the base segment of the robot is recognized as an Articulation Robot. Pictures below.
When I use an older release of the program (Isaac Sim2023.1.0-hotfix.1) everything works as it should, and the robot is recognized as an Articulation Robot, not the robot base segment. Pictures below.
Thank you very much @edsonbffilho for your quick reply.
I saw the post, and I understand the idea why the Articulation Robot was introduced to be the base link of the robot. Unfortunately, as far as I can see, connecting the Isaac Sim to ROS is a problem with that approach.
If I use a model generated via the URDF importer in an older release (when the robot is set as Articulation Robot), it is possible to use the robot via ROS. In the case when I use the latest release (when the base link of the robot is treated as an Articulation Robot), in that case if I select the robot as a target for ROS Publish Joint State and Articulation Controller as described in the tutorial, in that case I get an error (pictures below).
If I select the base link as a target , then the robot can not be moved (although the error is not printed in that case - picture below). I followed the tutorial, but I was not able to make the system work that way in the new release (as opposed to the old release where the everything is functional and the robot can be controlled via ROS).
A short update. I’m back to this topic again (so far I’ve been using the robot imported in the Isaac Sim 2022 version). I managed to solve the problem somewhat (at least the error I mentioned in this post). I tried in Isaac Sim 2023.1.1 as well as Isaac Sim 4.2 version.
When I set the Articulation root to the link_0 robot, the problem was solved. What I have been doing so far, and what has been causing me problems, is that I have been placing the Articulation root on the base_link of the robot. Robot behavior is not the same. Joint parameters must be adjusted differently in this case (this is what I’m trying to set up right now).
What is confusing and would be good to clarify is that in this video (20:40) when importing the robot via the OnShape, the Articulation root is set to the whole robot, not the base (the video says that it is better to set it to robot base, but I didn’t understand why). Also, confusingly, when running the Isaac Examples > ROS > MoveIT example, the Articulation root of the Frank robot is also set to the entire robot, not the base segment (image below), which is not possible using the URDF importer.
