Using Cyclone DDS with the Simulator

This guide configures the Clearpath simulator to use rmw_cyclonedds_cpp without connecting the simulated robot to a physical fleet. For custom Cyclone network profiles and remote computer communication, see the Cyclone ROS middleware guid e.

Configure the simulator

Use a separate setup directory for simulation so its configuration does not overwrite the configuration used by a physical robot or another setup.

mkdir -p ~/clearpath_sim

Copy a valid Clearpath robot.yaml into the new directory. Edit ~/clearpath_sim/robot.yaml. Keep the existing system: mapping, set a unique host name and ROS namespace, and use a domain ID separate from the physical robots. For example, use domain 27 for simulation when the physical robots use domain 26:

system:
  hosts:
    - hostname: a300-sim
  ros2:
    namespace: a300_sim
    domain_id: 27
    middleware:
      implementation: rmw_cyclonedds_cpp

The host name accepts letters, numbers, and hyphens; the ROS namespace may contain underscores. Do not add a custom profile or CYCLONEDDS_URI for this local simulation setup. Cyclone DDS uses its default configuration, and the separate domain keeps simulated ROS traffic isolated from the physical fleet.

The Cyclone profile XML instructions are for intentional communication between a physical robot and a remote computer. Do not copy that profile into the simulator setup when you want the simulation isolated from physical robots; it can configure network interfaces and peer addresses for that other use case.

Install the Cyclone RMW package if it is not already installed:

sudo apt update
sudo apt install ros-jazzy-rmw-cyclonedds-cpp

Launch the simulation

In a terminal, source ROS and select Cyclone DDS with the simulator domain. Clear any inherited custom profile before launching:

source /opt/ros/jazzy/setup.bash
export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp
export ROS_DOMAIN_ID=27
unset CYCLONEDDS_URI
ros2 launch clearpath_gz simulation.launch.py setup_path:=$HOME/clearpath_sim

The simulator generates its launch and parameter files under ~/clearpath_sim; it does not create a setup.bash file there. The simulator should use domain 27, separate from the physical fleet's domain 26.

Verify communication

In a second terminal, set the same environment and inspect topics under the simulator namespace:

source /opt/ros/jazzy/setup.bash
export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp
export ROS_DOMAIN_ID=27
unset CYCLONEDDS_URI
ros2 daemon stop
ros2 topic list | grep '^/a300_sim/'

The list should include simulator topics, such as /a300_sim/platform/odom/filtered, along with /parameter_events and /rosout. Verify that data is being published:

ros2 topic echo /a300_sim/platform/odom/filtered

Available topics depend on the selected platform and running simulator plugins.

Troubleshooting

• Only /parameter_events and /rosout appear. Confirm both terminals use rmw_cyclonedds_cpp and domain 27. Ensure CYCLONEDDS_URI is unset unless you intentionally configured a profile for simulation. The simulator does not generate ~/clearpath_sim/setup.bash.
• The simulator discovers topics from physical robots. Stop the simulator and restart it with domain 27; keep the physical robots on domain 26. Stop any ROS nodes that were started in the wrong domain and restart the ROS 2 daemon after sourcing the corrected environment.
• Gazebo waits for robot_description and no robot appears. Check the launch output for errors from robot_state_publisher or the simulator spawn process. Confirm the launch terminal has RMW_IMPLEMENTATION=rmw_cyclonedds_cpp, domain 27, and no unintended Cyclone profile.
• ros2 reports that rmw_cyclonedds_cpp cannot be loaded. Install ros-jazzy-rmw-cyclonedds-cpp and ensure the ROS 2 Jazzy setup has been sourced.