Isaac Sim: TASK articulations BUILDING ERROR

Hello, I’m trying to define a reinforcement learning task with our own robot. The purpose is that I try to add my robot to the stage and wish to get observations and send action to the robot. So in the set_up_scene class, I try to load my robot and add it to the stage, the code is as follow:
usd_path = “D:/isaac/ku/isaac_sim-2022.2.1/new/hiro_hand_rev6.usd”
create_prim(prim_path=“/World/hirohand_”, prim_type=“Xform”)
add_reference_to_stage(usd_path, prim_path=“/World/hirohand_”)
self.hiro_hand = scene.add(Robot(“/World/hirohand_”))

then the error occurs as: 

2023-05-14 07:00:54 [102,345,300ms] [Warning] [omni.isaac.dynamic_control.plugin] Failed to find articulation at ‘/World/hirohand_’
2023-05-14 07:00:54 [102,345,300ms] [Error] [omni.isaac.dynamic_control.plugin] DcGetArticulationRootBody: Invalid or expired articulation handle
2023-05-14 07:00:54 [102,345,300ms] [Warning] [omni.physx.tensors.plugin] Failed to find articulation at ‘/World/hirohand_’
2023-05-14 07:00:54 [102,345,300ms] [Error] [omni.physx.tensors.plugin] Pattern ‘/World/hirohand_’ did not match any articulations

2023-05-14 07:00:54 [102,345,300ms] [Error] [asyncio] Task exception was never retrieved
future: <Task finished coro=<BaseSampleExtension._on_load_world.._on_load_world_async() done, defined at d:\isaac\ku\isaac_sim-2022.2.1\exts\omni.isaac.examples\omni\isaac\examples\base_sample\> exception=AttributeError(“‘NoneType’ object has no attribute ‘is_homogeneous’”)>
Traceback (most recent call last):
File “d:\isaac\ku\isaac_sim-2022.2.1\exts\omni.isaac.examples\omni\isaac\examples\base_sample\”, line 151, in _on_load_world_async
await self._sample.load_world_async()
File “d:\isaac\ku\isaac_sim-2022.2.1\exts\omni.isaac.examples\omni\isaac\examples\base_sample\”, line 47, in load_world_async
await self._world.reset_async()
File “d:\isaac\ku\isaac_sim-2022.2.1\exts\omni.isaac.core\omni\isaac\core\world\”, line 314, in reset_async
File “d:\isaac\ku\isaac_sim-2022.2.1\exts\omni.isaac.core\omni\isaac\core\scenes\”, line 292, in _finalize
File “d:\isaac\ku\isaac_sim-2022.2.1\exts\omni.isaac.core\omni\isaac\core\articulations\”, line 163, in initialize
File “d:\isaac\ku\isaac_sim-2022.2.1\exts\omni.isaac.core\omni\isaac\core\articulations\”, line 201, in initialize
assert self._physics_view.is_homogeneous
File “d:\isaac\ku\isaac_sim-2022.2.1\kit\extsphysics\omni.physics.tensors-104.2.4-5.1\omni\physics\tensors\impl\”, line 156, in is_homogeneous
return self._backend.is_homogeneous
AttributeError: ‘NoneType’ object has no attribute ‘is_homogeneous’

Thanks very much for your answer!

Hi @weidh21 - Someone from our team will review your issue and get back to you.

1 Like

thanks, I solve this by re-check the articulation setting in my .usd file. Instead of set articulation root to the base link, I add it to the whole structure and it works

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