[BUG FIX] Refine IPC Coupling Logic

examples/IPC_Solver/ipc_momentum.py

@@ -21,8 +21,6 @@ def main():
             gravity=(0.0, 0.0, 0.0),
         ),
         coupler_options=gs.options.IPCCouplerOptions(
-            constraint_strength_translation=1,  # Translation strength ratio
-            constraint_strength_rotation=1,  # Rotation strength ratio
             enable_rigid_rigid_contact=False,
         ),
         viewer_options=gs.options.ViewerOptions(
@@ -61,6 +59,7 @@ def main():
             rho=1000,
             friction=0.3,
             coup_type="two_way_soft_constraint",
+            coup_stiffness=(1.0, 1.0),
         ),
         surface=gs.surfaces.Plastic(
             color=(0.8, 0.2, 0.2, 0.8),

examples/IPC_Solver/ipc_objects_falling.py

@@ -26,7 +26,6 @@ def main():
         ),
         coupler_options=gs.options.IPCCouplerOptions(
             contact_d_hat=0.01,  # Contact barrier distance (10mm) - must be appropriate for mesh resolution
-            two_way_coupling=True,  # Enable two-way coupling (forces from IPC to Genesis rigid bodies)
         ),
         viewer_options=gs.options.ViewerOptions(
             camera_pos=(2.5, 2.5, 1.5),
@@ -36,7 +35,12 @@ def main():
     )
 
     # Ground plane
-    scene.add_entity(gs.morphs.Plane())
+    scene.add_entity(
+        gs.morphs.Plane(),
+        material=gs.materials.Rigid(
+            coup_type="ipc_only",
+        ),
+    )
 
     # Cloth using Cloth material
     # Note: Using coarse grid mesh to avoid IPC thickness violations

examples/IPC_Solver/ipc_robot_cloth_teleop.py

@@ -46,8 +46,6 @@ def main():
             dt=0.02,
         ),
         coupler_options=gs.options.IPCCouplerOptions(
-            constraint_strength_translation=100.0,
-            constraint_strength_rotation=100.0,
             n_linesearch_iterations=8,
             linesearch_report_energy=False,
             newton_tolerance=1e-1,
@@ -68,7 +66,12 @@ def main():
     )
 
     # Add flat floor
-    scene.add_entity(gs.morphs.Plane())
+    scene.add_entity(
+        gs.morphs.Plane(),
+        material=gs.materials.Rigid(
+            coup_type="ipc_only",
+        ),
+    )
 
     # Add Franka robot
     franka_material_kwargs = dict(

examples/IPC_Solver/ipc_robot_grasp_cube.py

@@ -21,8 +21,6 @@ def main():
     coupler_options = None
     if not args.no_ipc:
         coupler_options = gs.options.IPCCouplerOptions(
-            constraint_strength_translation=10.0,
-            constraint_strength_rotation=10.0,
             enable_rigid_rigid_contact=False,
             enable_rigid_ground_contact=False,
             newton_translation_tolerance=10.0,
@@ -40,11 +38,17 @@ def main():
         show_viewer=args.vis,
     )
 
-    scene.add_entity(gs.morphs.Plane())
+    scene.add_entity(
+        gs.morphs.Plane(),
+        material=gs.materials.Rigid(
+            coup_type="ipc_only",
+        ),
+    )
 
     franka_material_kwargs = dict(
         coup_friction=0.8,
         coup_type=args.coup_type,
+        coup_stiffness=(10.0, 10.0),
     )
     if args.coup_type == "two_way_soft_constraint":
         franka_material_kwargs["coup_links"] = ("left_finger", "right_finger")
@@ -85,13 +89,10 @@ def main():
     franka.set_dofs_kp([4500.0, 4500.0, 3500.0, 3500.0, 2000.0, 2000.0, 2000.0, 500.0, 500.0])
 
     qpos = franka.inverse_kinematics(link=end_effector, pos=[0.65, 0.0, 0.4], quat=[0.0, 1.0, 0.0, 0.0])
-    if not args.no_ipc or args.coup_type == "external_articulation":
-        franka.control_dofs_position(qpos[motors_dof], dofs_idx_local=motors_dof)
-        franka.control_dofs_position(0.04, dofs_idx_local=fingers_dof)
-        for _ in range(200 if "PYTEST_VERSION" not in os.environ else 1):
-            scene.step()
-    else:
-        franka.set_dofs_position(qpos)
+    qpos[fingers_dof] = 0.04
+    franka.control_dofs_position(qpos)
+    for _ in range(200 if "PYTEST_VERSION" not in os.environ else 1):
+        scene.step()
 
     # Lower the grapper half way to grasping position
     qpos = franka.inverse_kinematics(link=end_effector, pos=[0.65, 0.0, 0.25], quat=[0.0, 1.0, 0.0, 0.0])