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[isaacsim.ros2.sim_control] ROS 2 Simulation Control#

Version: 1.6.5

Overview#

The isaacsim.ros2.sim_control extension bridges Isaac Sim with ROS 2 by implementing the standard simulation_interfaces ROS 2 package. It enables external ROS 2 nodes to control Isaac Sim’s timeline, spawn and delete entities, query simulation state, and manage worlds through service-based and action-based communication.

Key Components#

The extension exposes two main classes:

  • ROS2ServiceManager — Singleton that owns the ROS 2 node, MultiThreadedExecutor, and ReentrantCallbackGroup. Provides register_service() and register_action_server() methods for attaching handlers at startup.

  • SimulationControl — Registers all 19 services and the SimulateSteps action server against the ROS2ServiceManager. Implements each callback using Isaac Sim’s experimental prims API and stage utilities.

Helper utilities in isaacsim.ros2.sim_control include:

  • get_filtered_entities — Traverses the USDRT stage and applies optional regex filtering to return matching prim paths.

  • get_entity_state — Async function that retrieves pose, linear velocity, and angular velocity for a given entity, using RigidPrim for rigid bodies or XformPrim for other prims.

  • create_empty_entity_state — Returns an EntityState message with default zero values.

Functionality#

Timeline control#

The extension registers ROS 2 services to control Isaac Sim’s simulation timeline:

  • Get/Set simulation state: Query or set the simulation state (STOPPED, PLAYING, PAUSED).

  • Step simulation: Advance the simulation by a specified number of physics frames while paused.

  • Reset simulation: Remove all entities spawned via SpawnEntity or SpawnEntities and restore the stage to its original state.

The SimulateSteps action server provides step-by-step execution with per-frame feedback, allowing clients to monitor progress and cancel mid-run.

Entity management#

The extension supports dynamic entity operations through ROS 2 services:

  • Spawn entity: Create a new entity from a USD asset URI or as an empty Xform prim. Duplicate names are auto-renamed. Spawned entities are tagged with simulationInterfacesSpawned so ResetSimulation can remove them.

  • Spawn entities: Batch-spawn multiple entities in a single request, with per-entity success/error results.

  • Delete entity: Remove an entity from the stage by prim path.

  • Get entities: List all prim paths in the stage, with optional regex filtering.

  • Get entity info: Return the category of an entity (currently always OBJECT).

  • Get entity bounds: Return the world-space axis-aligned bounding box (AABB) of an entity as a TYPE_BOX geometry.

Entity state#

  • Get entity state: Retrieve pose, linear velocity, and angular velocity for a prim. Rigid bodies return full velocity data; non-rigid bodies return pose only.

  • Get entities states: Batch-retrieve states for multiple entities, with optional regex filtering.

  • Set entity state: Set the pose and optionally the linear and angular velocity of an entity at runtime.

World management#

  • Load world: Open a USD world file onto the stage, with optional asset root path prefix expansion.

  • Unload world: Clear the current stage and create a new empty anonymous stage.

  • Get current world: Return information about the currently loaded world, including its resource URI.

  • Get available worlds: Discover USD world files in configured search paths, with tag-based filtering using ANY or ALL matching modes.

Asset and feature discovery#

  • Get spawnables: Discover available USD assets from /Isaac/Samples/ROS2/Robots in the Isaac assets root path, plus any additional caller-supplied source paths.

  • Get simulator features: Return the list of simulation_interfaces features supported by this extension.

Integration#

The extension depends on:

  • isaacsim.ros2.bridge — Provides the ROS 2 context and rclpy bindings used by ROS2ServiceManager.

  • isaacsim.core.experimental.prims — Supplies RigidPrim and XformPrim for reading and writing entity poses and velocities.

  • isaacsim.core.experimental.utils — Supplies stage utilities (open_stage_async, create_new_stage_async) and prim utilities used by world and entity operations.

  • isaacsim.storage.native — Supplies get_assets_root_path_async, resolve_asset_path_async, find_filtered_files_async, and is_local_path for asset URI resolution and discovery.

Service callbacks execute on a MultiThreadedExecutor with a ReentrantCallbackGroup, allowing multiple services to run concurrently. Async Isaac Sim operations are bridged to the synchronous ROS 2 callback thread using nest_asyncio.

Enable Extension#

The extension can be enabled (if not already) in one of the following ways:

Define the next entry as an application argument from a terminal.

APP_SCRIPT.(sh|bat) --enable isaacsim.ros2.sim_control

Define the next entry under [dependencies] in an experience (.kit) file or an extension configuration (extension.toml) file.

[dependencies]
"isaacsim.ros2.sim_control" = {}

Open the Window > Extensions menu in a running application instance and search for isaacsim.ros2.sim_control. Then, toggle the enable control button if it is not already active.