[Question] Jacobian Retrieval Failure for Whole-Body Loco-Manipulation System

[YuHoChau]

Question

Hi, I have been working on a loco-manipulation whole-body control project using a robot with an arm mounted on a quadruped robot dog. I encountered a problem while trying to obtain the Jacobian matrix using the Isaac Sim API robot.root_physx_view.get_jacobians(). Specifically, I have converted the robot from URDF to USD, when fix the base of the robot, following the IK tutorial, the arm can suffessfuly reach to the target:

Nevertheless, when not fixed the robot (the robot would apply torque on legs for standing), the IK would be failed:

I’ve provided more details, including the USD file and the code I used, in this forum post: https://forums.developer.nvidia.com/t/urdf-to-usd-joint-index-discrepancy-causing-physx-jacobian-retrieval-failure/330417. My current assumption is that the issue stems from the USD file, where the joint indices for the arm and leg are mixed together. However, I’m not sure how to modify this in the USD file. I would greatly appreciate any insights or suggestions.

[RandomOakForest]

Thank you for posting this. I will move this post to our Discussions section for the team to follow up.

[YuHoChau]

The issue has been solved: https://forums.developer.nvidia.com/t/urdf-to-usd-joint-index-discrepancy-causing-physx-jacobian-retrieval-failure/330417