[Newton] Adds IMU Sensor (#5264)

# Description

- Adds a Newton-backend IMU sensor (`isaaclab_newton.sensors.imu`) that
wraps Newton's native `SensorIMU`, providing angular velocity and linear
acceleration in the sensor's body frame
- Extends `NewtonManager` with `request_state_attribute()` /
`request_contact_attribute()` for sensors to declare required extended
attributes before model finalization
- Adds IMU sensor lifecycle management to `NewtonManager`
(`add_imu_sensor()`, per-step updates in `_simulate_physics_only()`)
- Wires Newton IMU into the base `Imu`/`ImuData` factory classes for
automatic backend dispatch
- Uses site injection via `cl_register_site()`.

Author: camevor

source/isaaclab/config/extension.toml

@@ -1,7 +1,7 @@
 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "4.6.2"
+version = "4.6.3"
 
 # Description
 title = "Isaac Lab framework for Robot Learning"

source/isaaclab/docs/CHANGELOG.rst

@@ -1,6 +1,17 @@
 Changelog
 ---------
 
+4.6.3 (2026-04-16)
+~~~~~~~~~~~~~~~~~~~
+
+Changed
+^^^^^^^
+
+* Changed :class:`~isaaclab.sensors.imu.Imu` and
+  :class:`~isaaclab.sensors.imu.ImuData` factory type annotations to include
+  the Newton IMU backend types.
+
+
 4.6.2 (2026-04-14)
 ~~~~~~~~~~~~~~~~~~~
 

source/isaaclab/isaaclab/sensors/imu/imu.py

@@ -13,15 +13,17 @@
 from .base_imu_data import BaseImuData
 
 if TYPE_CHECKING:
+    from isaaclab_newton.sensors.imu import Imu as NewtonImu
+    from isaaclab_newton.sensors.imu import ImuData as NewtonImuData
     from isaaclab_physx.sensors.imu import Imu as PhysXImu
     from isaaclab_physx.sensors.imu import ImuData as PhysXImuData
 
 
 class Imu(FactoryBase, BaseImu):
     """Factory for creating IMU sensor instances."""
 
-    data: BaseImuData | PhysXImuData
+    data: BaseImuData | PhysXImuData | NewtonImuData
 
-    def __new__(cls, *args, **kwargs) -> BaseImu | PhysXImu:
+    def __new__(cls, *args, **kwargs) -> BaseImu | PhysXImu | NewtonImu:
         """Create a new instance of an IMU sensor based on the backend."""
         return super().__new__(cls, *args, **kwargs)

source/isaaclab/isaaclab/sensors/imu/imu_data.py

@@ -14,12 +14,13 @@
 from .base_imu_data import BaseImuData
 
 if TYPE_CHECKING:
+    from isaaclab_newton.sensors.imu import ImuData as NewtonImuData
     from isaaclab_physx.sensors.imu import ImuData as PhysXImuData
 
 
 class ImuData(FactoryBase, BaseImuData):
     """Factory for creating IMU data instances."""
 
-    def __new__(cls, *args, **kwargs) -> BaseImuData | PhysXImuData:
+    def __new__(cls, *args, **kwargs) -> BaseImuData | PhysXImuData | NewtonImuData:
         """Create a new instance of IMU data based on the backend."""
         return super().__new__(cls, *args, **kwargs)

source/isaaclab_newton/config/extension.toml

@@ -1,7 +1,7 @@
 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "0.5.13"
+version = "0.5.14"
 
 # Description
 title = "Newton simulation interfaces for IsaacLab core package"

source/isaaclab_newton/docs/CHANGELOG.rst

@@ -1,6 +1,17 @@
 Changelog
 ---------
 
+0.5.14 (2026-04-14)
+~~~~~~~~~~~~~~~~~~~
+
+Added
+^^^^^
+
+* Added :class:`~isaaclab_newton.sensors.Imu` sensor wrapping Newton's
+  ``SensorIMU``, providing angular velocity and linear acceleration in the
+  sensor's body frame.
+
+
 0.5.13 (2026-04-13)
 ~~~~~~~~~~~~~~~~~~~
 

source/isaaclab_newton/isaaclab_newton/physics/newton_manager.py

@@ -30,6 +30,7 @@
 from newton._src.usd.schemas import SchemaResolverNewton, SchemaResolverPhysx
 from newton.sensors import SensorContact as NewtonContactSensor
 from newton.sensors import SensorFrameTransform
+from newton.sensors import SensorIMU as NewtonSensorIMU
 from newton.solvers import SolverBase, SolverFeatherstone, SolverMuJoCo, SolverNotifyFlags, SolverXPBD
 
 from isaaclab.physics import PhysicsEvent, PhysicsManager
@@ -102,6 +103,9 @@ class NewtonManager(PhysicsManager):
     _collision_cfg: NewtonCollisionPipelineCfg | None = None
     _newton_contact_sensors: dict = {}  # Maps sensor_key to NewtonContactSensor
     _newton_frame_transform_sensors: list = []  # List of SensorFrameTransform
+    _newton_imu_sensors: list = []  # List of NewtonSensorIMU
+    _pending_extended_state_attributes: set[str] = set()
+    _pending_extended_contact_attributes: set[str] = set()
     _report_contacts: bool = False
     _fk_dirty: bool = False
 
@@ -391,6 +395,7 @@ def clear(cls):
         cls._collision_cfg = None
         cls._newton_contact_sensors = {}
         cls._newton_frame_transform_sensors = []
+        cls._newton_imu_sensors = []
         cls._report_contacts = False
         cls._fk_dirty = False
         cls._graph = None
@@ -402,6 +407,8 @@ def clear(cls):
         cls._model_changes = set()
         cls._cl_pending_sites = {}
         cls._cl_site_index_map = {}
+        cls._pending_extended_state_attributes = set()
+        cls._pending_extended_contact_attributes = set()
         cls._views = []
 
     @classmethod
@@ -458,6 +465,32 @@ def cl_register_site(cls, body_pattern: str | None, xform: wp.transform) -> str:
         cls._cl_pending_sites[key] = (label, xform)
         return label
 
+    @classmethod
+    def request_extended_state_attribute(cls, attr: str) -> None:
+        """Request an extended state attribute (e.g. ``"body_qdd"``).
+
+        Sensors call this during ``__init__``, before model finalization.
+        Attributes are forwarded to the builder in :meth:`start_simulation`
+        so that subsequent ``model.state()`` calls allocate them.
+
+        Args:
+            attr: State attribute name (must be in ``State.EXTENDED_ATTRIBUTES``).
+        """
+        cls._pending_extended_state_attributes.add(attr)
+
+    @classmethod
+    def request_extended_contact_attribute(cls, attr: str) -> None:
+        """Request an extended contact attribute (e.g. ``"force"``).
+
+        Sensors call this during ``__init__``, before model finalization.
+        Attributes are forwarded to the model in :meth:`start_simulation`
+        so that subsequent ``Contacts`` creation includes them.
+
+        Args:
+            attr: Contact attribute name.
+        """
+        cls._pending_extended_contact_attributes.add(attr)
+
     @classmethod
     def _cl_inject_sites(
         cls,
@@ -598,11 +631,18 @@ def start_simulation(cls) -> None:
         device = PhysicsManager._device
         logger.info(f"Finalizing model on device: {device}")
         cls._builder.up_axis = Axis.from_string(cls._up_axis)
+        # Forward pending extended attribute requests to builder and clear them
+        if cls._pending_extended_state_attributes:
+            cls._builder.request_state_attributes(*cls._pending_extended_state_attributes)
+            cls._pending_extended_state_attributes = set()
         with Timer(name="newton_finalize_builder", msg="Finalize builder took:"):
             cls._model = cls._builder.finalize(device=device)
             cls._model.set_gravity(cls._gravity_vector)
             cls._model.num_envs = cls._num_envs
 
+        if cls._pending_extended_contact_attributes:
+            cls._model.request_contact_attributes(*cls._pending_extended_contact_attributes)
+            cls._pending_extended_contact_attributes = set()
         cls._state_0 = cls._model.state()
         cls._state_1 = cls._model.state()
         cls._control = cls._model.control()
@@ -1010,6 +1050,11 @@ def step_fn(state_0, state_1):
             for sensor in cls._newton_frame_transform_sensors:
                 sensor.update(cls._state_0)
 
+        # Update IMU sensors
+        if cls._newton_imu_sensors:
+            for sensor in cls._newton_imu_sensors:
+                sensor.update(cls._state_0)
+
         # Populate contacts for contact sensors
         if cls._report_contacts:
             eval_contacts = contacts if contacts is not None else cls._contacts
@@ -1183,3 +1228,28 @@ def add_frame_transform_sensor(cls, shapes: list[int], reference_sites: list[int
         cls._newton_frame_transform_sensors.append(sensor)
         logger.info(f"Added frame transform sensor (index={idx}, shapes={len(shapes)})")
         return idx
+
+    @classmethod
+    def add_imu_sensor(cls, sites: list[int]) -> int:
+        """Add an IMU sensor for measuring acceleration and angular velocity at sites.
+
+        Creates a ``newton.sensors.SensorIMU`` from pre-resolved site indices,
+        appends it to the internal list, and returns its index.
+
+        Args:
+            sites: Ordered list of site indices (one per environment).
+
+        Returns:
+            Index of the newly created sensor in the internal IMU sensor list.
+        """
+        if cls._model is None:
+            raise RuntimeError("add_imu_sensor called before model finalization (start_simulation).")
+        sensor = NewtonSensorIMU(
+            cls._model,
+            sites=sites,
+            request_state_attributes=False,  # Already requested via NewtonManager
+        )
+        idx = len(cls._newton_imu_sensors)
+        cls._newton_imu_sensors.append(sensor)
+        logger.info(f"Added IMU sensor (index={idx}, sites={len(sites)})")
+        return idx

source/isaaclab_newton/isaaclab_newton/sensors/__init__.pyi

@@ -9,7 +9,10 @@ __all__ = [
     "ContactSensorCfg",
     "FrameTransformer",
     "FrameTransformerData",
+    "Imu",
+    "ImuData",
 ]
 
 from .contact_sensor import ContactSensor, ContactSensorData, ContactSensorCfg
 from .frame_transformer import FrameTransformer, FrameTransformerData
+from .imu import Imu, ImuData

source/isaaclab_newton/isaaclab_newton/sensors/frame_transformer/frame_transformer.py

@@ -331,7 +331,24 @@ def _update_buffers_impl(self, env_mask: wp.array):
     """
 
     def _invalidate_initialize_callback(self, event):
-        """Invalidates the scene elements."""
+        """Clears references to the native sensor and re-registers sites.
+
+        ``NewtonManager.close()`` calls ``clear()`` before dispatching ``STOP``,
+        so ``_cl_pending_sites`` is already empty when this callback fires.
+        Re-registering here ensures sites survive a close/reinit cycle.
+        """
         super()._invalidate_initialize_callback(event)
         self._newton_transforms = None
         self._sensor_index = None
+
+        # Re-register sites so a subsequent start_simulation picks them up.
+        self._world_origin_label = NewtonManager.cl_register_site(None, wp.transform())
+
+        source_offset = wp.transform(self.cfg.source_frame_offset.pos, self.cfg.source_frame_offset.rot)
+        self._source_label = NewtonManager.cl_register_site(self.cfg.prim_path, source_offset)
+
+        self._target_labels = []
+        for target_frame in self.cfg.target_frames:
+            target_offset = wp.transform(target_frame.offset.pos, target_frame.offset.rot)
+            label = NewtonManager.cl_register_site(target_frame.prim_path, target_offset)
+            self._target_labels.append(label)

source/isaaclab_newton/isaaclab_newton/sensors/imu/__init__.py

@@ -0,0 +1,10 @@
+# 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
+
+"""Sub-module for the Newton IMU sensor."""
+
+from isaaclab.utils.module import lazy_export
+
+lazy_export()