Isaac Sim ROS 2 Bridge

Purpose

Publish and subscribe to ROS 2 topics from Isaac Sim using OmniGraph bridge nodes, including Nav2 integration and multi-robot namespacing.

Limitations

• Targets Isaac Sim 6 / Kit 110 unless a section states otherwise.
• Does not replace official NVIDIA documentation for unsupported edge cases.

Troubleshooting

Error / symptom	Cause	Solution
No ROS topics	Bridge graph not playing or wrong domain	Press Play; set ROS_DOMAIN_ID consistently
Missing humble libs	LD_LIBRARY_PATH not set before process start	Fix the parent shell (source ROS env or use default launcher), then relaunch — do not hot-patch a running process
Namespaced topic mismatch	Frame or namespace drift	Align OmniGraph namespace with Nav2 config

Available Scripts

Script	Purpose	Arguments
scripts/multi_robot_namespacing.py	Fleet demo: play-gated per-robot bridge graphs (odom, TF, scan, joint states, cmd_vel) + shared clock	--robots NAME:PRIM_PATH [...] --usd_path --lidar_suffix --headless --test
scripts/prerequisites.sh	Prerequisites	positional args per script header (see script)

Running scripts

From agent runtimes that expose skill execution helpers, invoke helpers with run_script():

run_script("scripts/multi_robot_namespacing.py", args=["--help"])

From a built Isaac Sim tree, run the same file with ./python.sh (Linux) or python.bat (Windows) from _build/*/release, or execute shell helpers directly when they do not require the simulator.

Architecture

The ROS 2 Bridge in Isaac Sim 6.0 is extension-based (isaacsim.ros2.bridge) and built on OmniGraph action graphs. Publishers, subscribers, and services are only active when play is pressed.

Extension Stack

Extension	Purpose
isaacsim.ros2.core	Backend libraries, settings, lightweight ROS 2 libs
isaacsim.ros2.nodes	OmniGraph nodes for topics/services
isaacsim.ros2.bridge	Top-level bridge extension (enables all)
isaacsim.ros2.tf_viewer	TF tree visualization
isaacsim.ros2.urdf	URDF import with ROS 2 conventions
isaacsim.ros2.examples	Sample scenes (Nova Carter, iw_hub, hospital, office)
isaacsim.ros2.sim_control	Simulation control via ROS 2 services

Prerequisites

No manual setup is required for the default workflow. When isaacsim.ros2.core starts, it reads ROS_DISTRO; if unset, it falls back to the lightweight ROS 2 libs bundled inside the extension and sets internal_lib_fallback=True. The isaac-sim.sh / python.sh launchers auto-source setup_ros_env.sh, which exports ROS_DISTRO, RMW_IMPLEMENTATION, and the bundled ROS library path before the process starts.

Source a system ROS 2 install (/opt/ros/<distro>/setup.bash) in the parent shell only when you need message types or RMW implementations not provided by the bundled libs. On Linux, any LD_LIBRARY_PATH changes must exist before launching Isaac Sim because the dynamic linker reads them at process start; changing LD_LIBRARY_PATH after the process is already running does not retroactively fix ROS library resolution.

Pass --no-ros-env to bypass the auto-sourcing; in that case the parent shell must provide a working ROS 2 environment, including any required LD_LIBRARY_PATH entries.

ROS Environment Decision Rule

Use this precedence order when a user reports ROS 2 bridge startup or symbol-resolution issues:

1. Default path: launch via isaac-sim.sh / python.sh and let setup_ros_env.sh provide the bundled ROS environment.
2. System ROS path: if custom message packages or alternate RMW implementations are required, source /opt/ros/<distro>/setup.bash (and any overlay workspace) in the parent shell before launch.
3. Do not hot-patch LD_LIBRARY_PATH: if Isaac Sim is already running with the wrong loader environment, restart from a correctly sourced shell instead of trying to repair the process in-place.

Treat "export LD_LIBRARY_PATH and retry inside the current Isaac Sim process" as an anti-pattern; the corrective action is always "fix the parent shell, then relaunch."

[Code: scripts/prerequisites.sh]

OmniGraph ROS 2 Nodes

All ROS 2 communication is configured through OmniGraph action graphs. Key node types:

Publishers

Node Type	Topic Type	Use Case
ROS2PublishClock	rosgraph_msgs/Clock	Sim time sync
ROS2PublishJointState	sensor_msgs/JointState	Joint positions/velocities
ROS2PublishOdometry	nav_msgs/Odometry	Robot odometry
ROS2PublishLaserScan	sensor_msgs/LaserScan	Lidar data
ROS2PublishImage	sensor_msgs/Image	Camera RGB/depth
ROS2PublishCameraInfo	sensor_msgs/CameraInfo	Camera intrinsics
ROS2PublishTransformTree	tf2_msgs/TFMessage	TF frames
ROS2PublishSemanticLabels	std_msgs/String	Semantic segmentation labels
ROS2PublishPointCloud	sensor_msgs/PointCloud2	Lidar/depth point clouds
ROS2PublishImu	sensor_msgs/Imu	IMU data

Subscribers

Node Type	Topic Type	Use Case
ROS2SubscribeJointState	sensor_msgs/JointState	Joint commands
ROS2SubscribeTwist	geometry_msgs/Twist	Velocity commands (cmd_vel)
ROS2SubscribeAckermannDrive	ackermann_msgs/AckermannDriveStamped	Ackermann steering commands

Generic / extra

Node Type	Use case
ROS2Publisher / ROS2Subscriber	generic publish/subscribe for arbitrary message types
ROS2PublishBoundingBox2D / ROS2PublishBoundingBox3D	annotator output to ROS 2
ROS2PublishRgbd	combined RGB+D publishing
ROS2PublishSemanticSegmentation / ROS2PublishInstanceSegmentation	segmentation outputs

Setting Up a ROS 2 Bridge Graph (Python)

The repo ships a canonical reference for building a ROS 2 publishing action graph with og.Controller.edit(...), including connecting OnPlaybackTick to publisher nodes, wiring IsaacReadSimulationTime into a ROS2PublishClock, and creating a matching rclpy subscriber inside the same script.

• Reference example: source/standalone_examples/api/isaacsim.ros2.bridge/clock.py

When extending this pattern, use the current isaacsim.ros2.bridge.ROS2Publish* / ROS2Subscribe* node names (the legacy omni.isaac.ros2_bridge.* namespace is deprecated and will not load on Kit 110).

Migration: see Migrating ROS 2 OmniGraph nodes for the node-by-node rename map, and Renaming Extensions for the broader omni.isaac.* → isaacsim.* mapping.

Multi-Robot Namespacing

For multi-robot scenes, each robot needs its own namespace for ROS 2 topics. The repo's multi-robot scenario (Carter on hospital/office) demonstrates the manual loading + per-robot setup pattern; scripts/multi_robot_namespacing.py in this skill provides the full fleet bridge factory.

• Scenario reference: source/standalone_examples/api/isaacsim.ros2.bridge/carter_multiple_robot_navigation.py
• Fleet graph factory: scripts/multi_robot_namespacing.py

Play-Gated Activation

All bridge graphs use OnPlaybackTick as their execution trigger. This means:

1. Graphs are created while the stage is in a stopped state (no topics published).
2. Once app_utils.play() is called (or Play is pressed in the GUI), OnPlaybackTick fires each frame and drives all connected publishers/subscribers.
3. Stopping playback immediately silences all topics.

This is the correct pattern for fleet demos — Nav2 nodes can be launched and waiting before topics appear, and the fleet begins publishing atomically when Play starts.

API Usage

from multi_robot_namespacing import setup_fleet, create_ros2_bridge_for_robot

# Full fleet setup (clock + per-robot graphs)
setup_fleet([
    ("carter1", "/World/Carter1"),
    ("carter2", "/World/Carter2"),
    ("carter3", "/World/Carter3"),
])

# Or create individual robot graphs
create_ros2_bridge_for_robot(
    robot_name="carter1",
    robot_prim_path="/World/Carter1",
    lidar_prim_path="/World/Carter1/Lidar",
    publish_joint_states=True,
)

Per-Robot Published Topics (after Play)

Topic	Message Type	Frame
/<name>/odom	nav_msgs/Odometry	<name>/odom → <name>/base_link
/<name>/scan	sensor_msgs/LaserScan	<name>/lidar_link
/<name>/joint_states	sensor_msgs/JointState	—
/tf	tf2_msgs/TFMessage	robot subtree
/clock	rosgraph_msgs/Clock	shared, one graph

Subscribed Topics

Topic	Message Type	Use
/<name>/cmd_vel	geometry_msgs/Twist	Velocity commands from Nav2

Nav2 Integration

To use Nav2 with Isaac Sim ROS 2 Bridge:

1. Publish required topics: /odom, /tf, /scan (or /pointcloud), /joint_states
2. Subscribe to: /cmd_vel
3. Publish sim clock on /clock and set use_sim_time: true in Nav2 params

Known Issues (Isaac Sim 6.0 rc.22)

• ROS 2 bridge only activates on timeline.play() — topics are not published in stopped state
• Camera publishers require camera prims to have render products attached
• TF tree can become inconsistent if robot prim paths change at runtime
• Bundled ROS 2 libs may lack message types needed for custom topics — source a system ROS 2 install in the parent shell before launching Isaac Sim

Sample Scenes

Pre-built example USD files (from isaacsim.ros2.examples):

Scene	Path	Description
Nova Carter Navigation	/Isaac/Samples/ROS2/Scenario/carter_warehouse_navigation.usd	Single robot Nav2
Nova Carter Joint States	/Isaac/Samples/ROS2/Scenario/carter_warehouse_navigation_joint_states.usd	With joint state publishing
iw_hub Navigation	/Isaac/Samples/ROS2/Scenario/iw_hub_warehouse_navigation.usd	iw_hub AMR
Multi-Robot Navigation	ROS2/Navigation/Multiple Robots category	Fleet Nav2
Hospital Scene	/Isaac/Samples/ROS2/Scenario/hospital_scene.usd	Perceptor + hospital
Office Scene	/Isaac/Samples/ROS2/Scenario/office_scene.usd	Office navigation