Exposes physxscene:solveArticulationContactLast flag through PhysxCfg

source/isaaclab/config/extension.toml

@@ -1,7 +1,7 @@
 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "0.46.2"
+version = "0.46.3"
 
 # Description
 title = "Isaac Lab framework for Robot Learning"

source/isaaclab/docs/CHANGELOG.rst

@@ -1,6 +1,17 @@
 Changelog
 ---------
 
+0.46.3 (2025-09-17)
+~~~~~~~~~~~~~~~~~~~
+
+Changed
+^^^^^^^
+
+* Exposed parameter :attr:`~isaaclab.sim.spawners.PhysxCfg.solve_articulation_contact_last` 
+   to configure USD attribute ``physxscene:solveArticulationContactLast``. This parameter may
+   help improve solver stability with grippers, which previously required reducing simulation time-steps.
+  :class:`~isaaclab.sim.spawners.PhysxCfg`
+
 
 0.46.2 (2025-09-13)
 ~~~~~~~~~~~~~~~~~~~

source/isaaclab/isaaclab/sim/simulation_cfg.py

@@ -160,6 +160,26 @@ class PhysxCfg:
     gpu_max_particle_contacts: int = 2**20
     """Size of particle contacts stream buffer allocated in pinned host memory. Default is 2 ** 20."""
 
+    solve_articulation_contact_last: bool = False
+    """Changes the ordering inside the articulation solver. Default is False.
+
+    PhysX employs a strict ordering for handling constraints in an articulation. The outcome of 
+    each constraint resolution modifies the joint and associated link speeds. However, the default
+    ordering may not be ideal for gripping scenarios because the solver favours the contraint
+    types that are resolved last. This is particularly true of stiff constraint systems that are hard 
+    to resolve without resorting to vanishingly small simulation timesteps.
+
+    With dynamic contact resolution being such an important part of gripping, it may make
+    more sense to solve dynamic contact towards the end of the solver rather than at the
+    beginning. This parameter modifies the default ordering to enable this change.
+
+    For more information, please check `here <https://docs.omniverse.nvidia.com/kit/docs/omni_physics/107.3/dev_guide/guides/articulation_stability_guide.html#articulation-solver-order>`__.
+
+    .. versionadded:: v2.3
+        This parameter is only available with Isaac Sim 5.1.
+
+    """
+
 
 @configclass
 class RenderCfg:

source/isaaclab/isaaclab/sim/simulation_context.py

@@ -29,7 +29,7 @@
 from isaacsim.core.utils.carb import get_carb_setting, set_carb_setting
 from isaacsim.core.utils.viewports import set_camera_view
 from isaacsim.core.version import get_version
-from pxr import Gf, PhysxSchema, Usd, UsdPhysics
+from pxr import Gf, PhysxSchema, Sdf, Usd, UsdPhysics
 
 from isaaclab.sim.utils import create_new_stage_in_memory, use_stage
 
@@ -758,6 +758,10 @@ def _set_additional_physx_params(self):
         physx_scene_api.CreateGpuCollisionStackSizeAttr(self.cfg.physx.gpu_collision_stack_size)
         # -- Improved determinism by PhysX
         physx_scene_api.CreateEnableEnhancedDeterminismAttr(self.cfg.physx.enable_enhanced_determinism)
+        # -- Set solve_articulation_contact_last by add attribute to the PhysxScene prim, and add attribute there.
+        physx_prim = physx_scene_api.GetPrim()
+        if self.cfg.physx.solve_articulation_contact_last:
+            physx_prim.CreateAttribute("physxScene:solveArticulationContactLast", Sdf.ValueTypeNames.Bool).Set(True)
 
         # -- Gravity
         # note: Isaac sim only takes the "up-axis" as the gravity direction. But physics allows any direction so we