Transformation change on non-root links is not supported

Omniverse Isaac Sim
1

I setup a scene with a track and a train like this:

from omni.isaac.examples.base_sample import BaseSample
from omni.isaac.core.utils.nucleus import find_nucleus_server
from omni.isaac.core.utils.stage import add_reference_to_stage
from omni.isaac.core.prims.xform_prim import XFormPrim
import omni.kit.commands
from pxr import Sdf, Usd, Gf

class DsdTrain1(BaseSample):
    def __init__(self) -> None:
        super().__init__()
        return

    def setup_scene(self):
        world = self.get_world()
        world.scene.add_default_ground_plane()
        result, nucleus_server = find_nucleus_server()
        if result is False:
            carb.log_error("Could not find nucleus server")
        asset_path = nucleus_server + "/Projects/dsd-assets/assets/"
        # Add track
        add_reference_to_stage(usd_path=asset_path + "tracks/track_straight_1.usd",
                               prim_path="/World/track")
        track = world.scene.add(XFormPrim(prim_path="/World/track", name="track"))
        omni.kit.commands.execute('ChangeProperty',
                                  prop_path=Sdf.Path('/World/track/Track/TrackColliderCurve.purpose'),
                                  value='proxy',
                                  prev=None)
        # Add train
        add_reference_to_stage(usd_path=asset_path + "vehicles/DB_BR_422_with_physics.usd",
                             prim_path="/World/train")
        train = world.scene.add(XFormPrim(prim_path="/World/train", name="train"))
    return

When the scene is loaded, I try to move the prim /World/train/ in the Isaac UI. I can actually move it, but get the following error output:

2021-12-02 16:18:55 [1,570,928ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Axle1
2021-12-02 16:18:55 [1,570,928ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Flange1
2021-12-02 16:18:55 [1,570,928ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Axle2
2021-12-02 16:18:55 [1,570,928ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Flange2
2021-12-02 16:18:55 [1,570,928ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Frame
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Axle1
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Flange1
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Axle2
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Flange2
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Frame
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Axle1
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Flange1
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Axle2
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Flange2
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Frame
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Axle1
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Flange1
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Axle2
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Flange2
2021-12-02 16:18:55 [1,570,929ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Frame
2021-12-02 16:18:55 [1,570,930ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Axle1
2021-12-02 16:18:55 [1,570,930ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Flange1
2021-12-02 16:18:55 [1,570,930ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Axle2
2021-12-02 16:18:55 [1,570,930ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Flange2
2021-12-02 16:18:55 [1,570,930ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Frame
2021-12-02 16:18:55 [1,570,930ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/Carriage_2
2021-12-02 16:18:55 [1,570,930ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/Carriage_3
2021-12-02 16:18:55 [1,570,930ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/Carriage_4
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Axle1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Flange1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Axle2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Flange2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_1/Bogie/Frame
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Axle1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Flange1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Axle2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Flange2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_end_4/Bogie/Frame
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Axle1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Flange1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Axle2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Flange2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_1_2/Bogie/Frame
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Axle1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Flange1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Axle2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Flange2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_2_3/Bogie/Frame
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Axle1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Flange1
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Axle2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Flange2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/bogie_mickeymouse_mid_3_4/Bogie/Frame
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/Carriage_2
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/Carriage_3
2021-12-02 16:18:55 [1,570,931ms] [Error] [omni.physx.plugin] Transformation change on non-root links is not supported. Link: /World/train/Train/Carriage_4

Any advice apprecitated.

2

Is the goal to move this prim while simulation is happening, or to set it position and then start simulation?

3

The goal is to move the asset before the simulation starts. I want to place a train precisely on a track by moving the Xform. I tried to get the code for moving via the command window. When I moved the prim via UI, I got the errors.

4

The reason I ask is because omni.physx shouldn’t run until play is pressed and simulation is happening. So that error shouldn’t print out, can you make a screencapture to show your process?

did a quick test here:
you can change the root link at any time even if simulating, but changing a non root link like a link on the franka arm cannot be done during simulation as that would conflict with the physics joint and would result in undefined behavior.

5

With my current setup and current Isaac Sim version, this problem does not persist.

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6

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