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

Available Scripts

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

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

Subscribers

Generic / extra

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)

Subscribed Topics

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):