Articulation for robot with large number of meshes

Hi Forum,

We are having difficulty applying articulation to our robot. As it is imported from CAD it consists of hundreds of meshes and that seems to be causing an issue when creating the articulation on the robot root layer. The simulation crashes if we try to articulate the robot using a differential controller using the imported model

Here is the warning we are seeing

[Warning] [omni.physx.plugin] PhysX warning: PxAggregate: can't add articulation, max number of shapes reached, FILE /buildAgent/work/74336105e89c4a74/source/physx/src/NpAggregate.cpp, LINE 365

The marked xform is where we are applying the articulation layer:

Three questions:

  • How can we increase the maximum number of allowed meshes for articulation physics?
  • Is this warning known? I was not able to find anything.
  • Is there a preferred workflow for articulation other than what can be read in the documentation (we have gone through them).

Open for other ideas as well.


I am moving your topic to the Isaac SIM category for better visibility.


1 Like

This seems like a critical function. Not being able to aggregate more than 128 bodies could be a blocker for several robotics companies using complex models. Am I using articulations in an unintended way? Can someone shine some light on this?

I have reached out in the discord as well, but no answer so far. It seems the number of max bodies was explicitly 128 in previous versions of the SDK for example PhysX SDK 3.4 below, but then removed in later version for example PhysX SDK 5.3.0. The limit still holds though, if I try to create an articulation with more than 128 bodies it will fail.

From PhysX SDK 3.4.0

From PhysX SDK 5.3.0

SDK docs

this is a bug on the integration side, there should be no limit, furthermore the aggregate itself is not needed anymore, I just did not updated my code yet to remove the aggregates.
Thats something I wont do for a patch release, but for the patch update of IsaacSim (end of the month) I should be able to fix the issue with the maximum number of shapes.
Sorry about the trouble,

Hi Ales,
Thanks for coming back on this - we were getting worried this would block us for a long time, good to hear a fix is coming end of month. To be clear a patch update is only applied when a new iteration of Isaac Sim is released or does it happen automatically? I.e., do we need to download a new version of Isaac Sim?

There should be a new version of IsaacSim - patch release soon.


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