ROS 2 Publish Real Time Factor (RTF)#

Learning Objectives#

This tutorial will demonstrate publishing the Real Time Factor (RTF) of Isaac Sim as a ROS2 Float 32 message.

Getting Started#

  • Enable the isaacsim.ros2.bridge Extension in the Extension Manager window by navigating to Window > Extensions.

Publish RTF#

The RTF indicates how fast or slow simulation is running with respect to the real-time. It is calculated per frame as RTF = simulated_elapsed_time / real_elapsed_time. If RTF > 1, simulation time is running faster than wall clock time. If RTF < 1, the simulation is running slower than real-time.

  1. Go to Tools > Robotics > ROS 2 OmniGraphs > Generic Publisher. The parameter pop-up window will appear.

  2. Select Publish RTF as Float32 and click OK.

  3. A new Action Graph will be created with the Isaac Real Time Factor node connected to a generic ROS2 Publisher node, which is setup to publish std_msgs/msg/Float32 ROS messages.

  4. Select the Action Graph prim found at /Graph/ROS_GenericPub. Right click on it and choose Open Graph. The autogenerated graph should be match the following:

  5. Click Play to start simulation.

  6. In a ROS2-sourced terminal run the following command to view the RTF value published from Isaac Sim.

    ros2 topic echo /topic

    For an unloaded system, RTF should be close to 1.0.

Summary#

This tutorial covered using an OmniGraph shortcut to automatically generate a ROS2 RTF publisher graph.

Next Steps#

  • Continue on to the next tutorial in our ROS2 Tutorials series, ROS 2 Cameras, to learn how to add cameras and receive ground truth synthetic perception data through ROS 2 topics.