Isaac Sim ROS 2 Bridge

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 LD_LIBRARY_PATH for the bundled libs 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, LD_LIBRARY_PATH must be set in the parent shell (the dynamic linker reads it at process start), which is why this step is shell-sourced and not handled by the extension at runtime.

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

[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 per-robot graph factory with namespaced odom / TF / cmd_vel.

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

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):