When I was configuring my Jackal 4 wheeled robot in Isaac Sim with ROS. A question arised: When I configure the Omni Graph for my 4 wheeled Jackal AGV in Isaac Sim, the default Articulation Root is the root of the USD(the top level Prim in Isaac Sim, here is World/Jackal) model, but it is wrong in the tf tree. But under this configuration the Omni Graph can subscibe the geometry/Twist msg from ROS and successfully transform the msg to wheel speeds of 4 wheels. But when I set the Articulation Root to base_link(correctly in URDF), the Omni Graph failed to transform the Twist to wheel speeds. The simulator says
OmniGraph Warning “NoneTygpe” Object has no attribute “is_homogeneous”
here is my 4 wheel robot cmd_vel Graph:
here is the model hierarchy:
here is the 4 revolute joints of Jackal:
How to solve this Problem?