Updates PhysX external forces default to True (#6523)

# Description

Default enable_external_forces_every_iteration to true for PhysX and
warn when users opt out with the deprecated flag.

Add a deprecation warning and a breaking changelog fragment.

## Type of change

<!-- As you go through the list, delete the ones that are not
applicable. -->

- Bug fix (non-breaking change which fixes an issue)
- Breaking change (existing functionality will not work without user
modification)

## Checklist

- [x] I have read and understood the [contribution
guidelines](https://isaac-sim.github.io/IsaacLab/main/source/refs/contributing.html)
- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [ ] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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---------

Signed-off-by: Kelly Guo <kellyg@nvidia.com>
Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

Author: kellyguo11

source/isaaclab/changelog.d/kellyg-default-external-forces.skip

@@ -0,0 +1 @@
+Internal: adjusted operational-space controller tests for the updated PhysX solver behavior.

source/isaaclab/test/controllers/test_operational_space.py

@@ -155,9 +155,9 @@ def sim():
     )
     d_ratio_set = torch.tensor(
         [
-            [1.0, 1.0, 1.0, 1.0, 1.0, 1.0],
-            [1.1, 1.1, 1.1, 1.1, 1.1, 1.1],
-            [0.9, 0.9, 0.9, 0.9, 0.9, 0.9],
+            [2.0, 2.0, 2.0, 2.0, 2.0, 2.0],
+            [2.2, 2.2, 2.2, 2.2, 2.2, 2.2],
+            [1.8, 1.8, 1.8, 1.8, 1.8, 1.8],
         ],
         device=sim.device,
     )
@@ -333,6 +333,7 @@ def test_franka_pose_abs_with_partial_inertial_decoupling(sim):
         goal_marker,
         contact_forces,
         frame,
+        rotation_tolerance=0.12,
     )
 
 
@@ -368,7 +369,7 @@ def test_franka_pose_abs_fixed_impedance_with_gravity_compensation(sim):
         partial_inertial_dynamics_decoupling=False,
         gravity_compensation=True,
         motion_stiffness_task=500.0,
-        motion_damping_ratio_task=1.0,
+        motion_damping_ratio_task=2.0,
     )
     osc = OperationalSpaceController(osc_cfg, num_envs=num_envs, device=sim_context.device)
 
@@ -1121,6 +1122,7 @@ def test_franka_pose_abs_with_partial_inertial_decoupling_nullspace_centering(si
         motion_stiffness_task=1000.0,
         motion_damping_ratio_task=1.0,
         nullspace_control="position",
+        nullspace_stiffness=1.0,
     )
     osc = OperationalSpaceController(osc_cfg, num_envs=num_envs, device=sim_context.device)
 
@@ -1136,6 +1138,7 @@ def test_franka_pose_abs_with_partial_inertial_decoupling_nullspace_centering(si
         goal_marker,
         contact_forces,
         frame,
+        rotation_tolerance=0.12,
     )
 
 
@@ -1172,6 +1175,7 @@ def test_franka_pose_abs_with_nullspace_centering(sim):
         motion_stiffness_task=500.0,
         motion_damping_ratio_task=1.0,
         nullspace_control="position",
+        nullspace_stiffness=1.0,
     )
     osc = OperationalSpaceController(osc_cfg, num_envs=num_envs, device=sim_context.device)
 
@@ -1426,6 +1430,8 @@ def _run_op_space_controller(
     contact_forces: ContactSensor | None,
     frame: str,
     convergence_steps: int = 500,
+    position_tolerance: float = 0.1,
+    rotation_tolerance: float = 0.1,
 ):
     """Run the operational space controller with the given parameters.
 
@@ -1442,6 +1448,8 @@ def _run_op_space_controller(
         contact_forces (ContactSensor | None): The contact forces sensor.
         frame (str): The reference frame for targets.
         convergence_steps (int): Number of simulation steps to run before checking convergence. Defaults to 500.
+        position_tolerance (float): Maximum position error norm. Defaults to 0.1.
+        rotation_tolerance (float): Maximum rotation error norm. Defaults to 0.1.
     """
     # Initialize the masks for evaluating target convergence according to selection matrices
     pos_mask = torch.tensor(osc.cfg.motion_control_axes_task[:3], device=sim.device).view(1, 3)
@@ -1501,7 +1509,17 @@ def _run_op_space_controller(
             # check that we converged to the goal
             if count > 0:
                 _check_convergence(
-                    osc, ee_pose_b, ee_target_pose_b, ee_force_b, command, pos_mask, rot_mask, force_mask, frame
+                    osc,
+                    ee_pose_b,
+                    ee_target_pose_b,
+                    ee_force_b,
+                    command,
+                    pos_mask,
+                    rot_mask,
+                    force_mask,
+                    frame,
+                    position_tolerance,
+                    rotation_tolerance,
                 )
             # reset joint state to default
             default_joint_pos = robot.data.default_joint_pos.torch.clone()
@@ -1774,6 +1792,8 @@ def _check_convergence(
     rot_mask: torch.tensor,
     force_mask: torch.tensor,
     frame: str,
+    position_tolerance: float,
+    rotation_tolerance: float,
 ):
     """Check the convergence to the target.
 
@@ -1787,6 +1807,8 @@ def _check_convergence(
         rot_mask (torch.tensor): The rotation mask.
         force_mask (torch.tensor): The force mask.
         frame (str): The reference frame for targets.
+        position_tolerance (float): Maximum position error norm.
+        rotation_tolerance (float): Maximum rotation error norm.
 
     Raises:
         AssertionError: If the convergence is not achieved.
@@ -1803,8 +1825,8 @@ def _check_convergence(
             # desired error (zer)
             des_error = torch.zeros_like(pos_error_norm)
             # check convergence
-            torch.testing.assert_close(pos_error_norm, des_error, rtol=0.0, atol=0.1)
-            torch.testing.assert_close(rot_error_norm, des_error, rtol=0.0, atol=0.1)
+            torch.testing.assert_close(pos_error_norm, des_error, rtol=0.0, atol=position_tolerance)
+            torch.testing.assert_close(rot_error_norm, des_error, rtol=0.0, atol=rotation_tolerance)
             cmd_idx += 7
         elif target_type == "pose_rel":
             pos_error, rot_error = compute_pose_error(
@@ -1815,8 +1837,8 @@ def _check_convergence(
             # desired error (zer)
             des_error = torch.zeros_like(pos_error_norm)
             # check convergence
-            torch.testing.assert_close(pos_error_norm, des_error, rtol=0.0, atol=0.1)
-            torch.testing.assert_close(rot_error_norm, des_error, rtol=0.0, atol=0.1)
+            torch.testing.assert_close(pos_error_norm, des_error, rtol=0.0, atol=position_tolerance)
+            torch.testing.assert_close(rot_error_norm, des_error, rtol=0.0, atol=rotation_tolerance)
             cmd_idx += 6
         elif target_type == "wrench_abs":
             force_target_b = ee_target_b[:, cmd_idx : cmd_idx + 3].clone()

source/isaaclab_physx/changelog.d/kellyg-default-external-forces.major.rst

@@ -0,0 +1,7 @@
+Changed
+^^^^^^^
+
+* **Breaking:** Changed :attr:`~isaaclab_physx.physics.PhysxCfg.enable_external_forces_every_iteration`
+  to default to ``True``. Remove explicit ``True`` overrides; explicit ``False``
+  overrides emit a ``DeprecationWarning`` because the PhysX flag will be removed
+  in a future release.

source/isaaclab_physx/isaaclab_physx/physics/physx_manager.py

@@ -15,6 +15,7 @@
 import os
 import re
 import time
+import warnings
 from collections.abc import Callable
 from datetime import datetime
 from enum import Enum
@@ -678,8 +679,18 @@ def _configure_physics(cls) -> None:
         sim_utils.bind_physics_material(sim_cfg.physics_prim_path, mat_path)
 
         # warnings
-        if cfg.solver_type == 1 and not cfg.enable_external_forces_every_iteration:
-            logger.warning("TGS solver with enable_external_forces_every_iteration=False may cause noisy velocities.")
+        if not cfg.enable_external_forces_every_iteration:
+            warning_message = (
+                "PhysxCfg.enable_external_forces_every_iteration is deprecated and will be removed in a future "
+                "PhysX release. External forces are applied every iteration by default; remove this override."
+            )
+            if cfg.solver_type == 1:
+                warning_message += " Disabling this behavior with the TGS solver may cause noisy velocities."
+            warnings.warn(
+                warning_message,
+                DeprecationWarning,
+                stacklevel=2,
+            )
         if not cfg.enable_stabilization and sim_cfg.dt > 0.0333:
             logger.warning("Large timestep without stabilization may cause physics issues.")
 

source/isaaclab_physx/isaaclab_physx/physics/physx_manager_cfg.py

@@ -147,18 +147,21 @@ class PhysxCfg(PhysicsCfg):
         Enabling this flag may lead to incorrect contact forces report from the contact sensor.
     """
 
-    enable_external_forces_every_iteration: bool = False
-    """Enable/disable external forces every position iteration in the TGS solver. Default is False.
+    enable_external_forces_every_iteration: bool = True
+    """Enable/disable external forces every position iteration in the TGS solver. Default is True.
 
     When using the TGS solver (:attr:`solver_type` is 1), this flag allows enabling external forces
     every solver position iteration. This can help improve the accuracy of velocity updates.
-    Consider enabling this flag if the velocities generated by the simulation are noisy.
-    Increasing the number of velocity iterations, together with this flag, can help improve
-    the accuracy of velocity updates.
+    Increasing the number of velocity iterations, together with this flag, can help improve the
+    accuracy of velocity updates.
 
     .. note::
 
         This flag is ignored when using the PGS solver (:attr:`solver_type` is 0).
+
+    .. deprecated:: TBD
+
+        This flag is deprecated and will be removed in a future PhysX release.
     """
 
     enable_enhanced_determinism: bool = False

source/isaaclab_physx/test/assets/test_rigid_object.py

@@ -649,7 +649,7 @@ def test_set_material_properties_via_view(num_cubes, device):
 @pytest.mark.parametrize("device", test_devices())
 @pytest.mark.isaacsim_ci
 def test_rigid_body_no_friction(num_cubes, device):
-    """Test that a rigid object with no friction will maintain it's velocity when sliding across a plane."""
+    """Test that a rigid object with no friction maintains its tangential velocity on a plane."""
     with build_simulation_context(device=device, auto_add_lighting=True) as sim:
         sim._app_control_on_stop_handle = None
         # Generate cubes scene
@@ -701,7 +701,7 @@ def test_rigid_body_no_friction(num_cubes, device):
                 tolerance = 1e-5
 
             torch.testing.assert_close(
-                cube_object.data.root_lin_vel_w.torch, initial_velocity[:, :3], rtol=1e-5, atol=tolerance
+                cube_object.data.root_lin_vel_w.torch[:, :2], initial_velocity[:, :2], rtol=1e-5, atol=tolerance
             )
 
 
@@ -858,8 +858,8 @@ def test_rigid_body_with_restitution(num_cubes, device):
                 curr_z_velocity = cube_object.data.root_lin_vel_w.torch[:, 2].clone()
 
                 if expected_collision_type == "inelastic":
-                    # assert that the block has not bounced by checking that the z velocity is less than or equal to 0
-                    assert (curr_z_velocity <= 0.0).all()
+                    # Allow a small contact separation velocity while ensuring that the block does not bounce.
+                    assert (curr_z_velocity <= 1e-3).all()
 
                 if torch.all(curr_z_velocity <= 0.0):
                     # Still in the air