Add SO-101 cube-stack task with XR teleoperation

Add an SO-101 (5-DOF) cube-stacking environment driven by XR
teleoperation through the IsaacTeleop retargeting pipeline.

- Add the SO-101 robot asset and register it in isaaclab_assets.
- Add Isaac-Stack-Cube-SO101 joint-position and IK-Abs task configs. The
  5-DOF arm uses position-only IK over four joints, with the wrist roll
  driven directly and an analog gripper, flattened to a 5D action
  [pos_x, pos_y, pos_z, roll, gripper].
- Build the teleop pipeline from three retargeters: a clutch
  (relative-origin EE pose), a wrist-roll swing-twist, and an analog
  gripper.

Clutch engage behavior, so engaging teleop does not jerk the arm:

- Latch the controller origin on the first RUNNING frame (the headset
  "Play"), re-arming whenever teleop is not running, so connecting the
  client never latches and every Play re-zeroes to the controller's
  current pose.
- Rotate the world-frame controller delta into the seated base frame
  (yawed +90 deg about +Z) before commanding the position-only IK.
- Latch the robot's live end-effector position, converted into the base
  frame, as the clutch home on engage instead of a fixed constant, so a
  steady controller leaves the arm still.

isaaclab_teleop: add IsaacTeleopCfg.ee_frame_prim_path; the device reads
that prim's world transform each frame and supplies it to the pipeline
as the robot_ee_pos ValueInput leaf (passed through verbatim, not
composed with the anchor/rebase transforms).

Add sim-free unit tests for the retargeter math: clutch rebasing,
world-to-base conversion against a scipy oracle, swing-twist roll, and
the analog gripper mapping.

Author: jiwenc-nv

source/isaaclab_assets/isaaclab_assets/robots/__init__.pyi

@@ -36,6 +36,8 @@ __all__ = [
     "RIDGEBACK_FRANKA_PANDA_CFG",
     "SAWYER_CFG",
     "SHADOW_HAND_CFG",
+    "SO101_CFG",
+    "SO101_HIGH_PD_CFG",
     "joint_parameter_lookup",
     "SPOT_CFG",
     "GO1_ACTUATOR_CFG",
@@ -85,6 +87,7 @@ from .quadcopter import CRAZYFLIE_CFG
 from .ridgeback_franka import RIDGEBACK_FRANKA_PANDA_CFG
 from .sawyer import SAWYER_CFG
 from .shadow_hand import SHADOW_HAND_CFG
+from .so101 import SO101_CFG, SO101_HIGH_PD_CFG
 from .spot import joint_parameter_lookup, SPOT_CFG
 from .unitree import (
     GO1_ACTUATOR_CFG,

source/isaaclab_assets/isaaclab_assets/robots/so101.py

@@ -0,0 +1,86 @@
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""Configuration for the TheRobotStudio SO-101 follower arm.
+
+The following configurations are available:
+
+* :obj:`SO101_CFG`: SO-101 5-DOF arm with a single-jaw gripper.
+* :obj:`SO101_HIGH_PD_CFG`: SO-101 with a stiffer PD controller for task-space (IK) tracking.
+
+The SO-101 is a low-cost 5-DOF arm (``shoulder_pan``, ``shoulder_lift``, ``elbow_flex``,
+``wrist_flex``, ``wrist_roll``) plus a single revolute ``gripper`` jaw. Because the arm has
+only 5 actuated DOF, it cannot achieve an arbitrary 6-DOF end-effector pose; task-space
+controllers should use position-only commands, optionally with a direct ``wrist_roll`` channel
+for roll (see the cube-stack IK-Abs task).
+
+Reference: https://github.com/TheRobotStudio/SO-ARM100
+Actuator gains follow the values tuned for simulation in LeIsaac.
+"""
+
+import isaaclab.sim as sim_utils
+from isaaclab.actuators import ImplicitActuatorCfg
+from isaaclab.assets.articulation import ArticulationCfg
+from isaaclab.utils.assets import ISAAC_NUCLEUS_DIR
+
+##
+# Configuration
+##
+
+SO101_CFG = ArticulationCfg(
+    spawn=sim_utils.UsdFileCfg(
+        usd_path=f"{ISAAC_NUCLEUS_DIR}/Robots/RobotStudio/so101_new_calib/so101_new_calib.usd",
+        activate_contact_sensors=False,
+        rigid_props=sim_utils.RigidBodyPropertiesCfg(
+            disable_gravity=False,
+            max_depenetration_velocity=5.0,
+        ),
+        articulation_props=sim_utils.ArticulationRootPropertiesCfg(
+            enabled_self_collisions=True,
+            solver_position_iteration_count=8,
+            solver_velocity_iteration_count=0,
+            fix_root_link=True,
+        ),
+    ),
+    init_state=ArticulationCfg.InitialStateCfg(
+        joint_pos={
+            "shoulder_pan": 0.0,
+            "shoulder_lift": 0.0,
+            "elbow_flex": 0.0,
+            "wrist_flex": 0.0,
+            "wrist_roll": 0.0,
+            "gripper": 0.0,
+        },
+    ),
+    actuators={
+        "arm": ImplicitActuatorCfg(
+            joint_names_expr=["shoulder_pan", "shoulder_lift", "elbow_flex", "wrist_flex", "wrist_roll"],
+            effort_limit_sim=10.0,
+            velocity_limit_sim=10.0,
+            stiffness=17.8,
+            damping=0.60,
+        ),
+        "gripper": ImplicitActuatorCfg(
+            joint_names_expr=["gripper"],
+            effort_limit_sim=10.0,
+            velocity_limit_sim=10.0,
+            stiffness=17.8,
+            damping=0.60,
+        ),
+    },
+    soft_joint_pos_limit_factor=1.0,
+)
+"""Configuration of the SO-101 follower arm with implicit actuators."""
+
+
+SO101_HIGH_PD_CFG = SO101_CFG.copy()
+SO101_HIGH_PD_CFG.spawn.rigid_props.disable_gravity = True
+SO101_HIGH_PD_CFG.actuators["arm"].stiffness = 400.0
+SO101_HIGH_PD_CFG.actuators["arm"].damping = 80.0
+"""Configuration of the SO-101 follower arm with stiffer PD control.
+
+This configuration is useful for task-space control using differential IK, where the
+default low-stiffness gains track end-effector targets poorly.
+"""

source/isaaclab_tasks/isaaclab_tasks/contrib/stack/config/so101/__init__.py

@@ -0,0 +1,35 @@
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+import gymnasium as gym
+
+##
+# Register Gym environments.
+##
+
+##
+# Joint Position Control
+##
+
+gym.register(
+    id="Isaac-Stack-Cube-SO101-v0",
+    entry_point="isaaclab.envs:ManagerBasedRLEnv",
+    kwargs={
+        "env_cfg_entry_point": f"{__name__}.stack_joint_pos_env_cfg:SO101CubeStackEnvCfg",
+    },
+    disable_env_checker=True,
+)
+
+##
+# Inverse Kinematics - Absolute Pose Control
+##
+
+gym.register(
+    id="Isaac-Stack-Cube-SO101-IK-Abs-v0",
+    entry_point="isaaclab.envs:ManagerBasedRLEnv",
+    kwargs={
+        "env_cfg_entry_point": f"{__name__}.stack_ik_abs_env_cfg:SO101CubeStackEnvCfg",
+    },
+    disable_env_checker=True,
+)