ROS2 use_sim_time parameter

[mohamedleithy]

Hello AWSIM-labs Team,

I am currently using AWSIM with ROS 2 and have encountered a challenge with simulation time management. Specifically, I am interested in enabling the use of the ROS 2 parameter "use_sim_time" so that the simulator properly subscribes to an externally published clock on the /clock topic.

Appreciate your support on this.

[maxime-clem]

so that the simulator properly subscribes to an externally published clock

If I understand correctly, you want to set TimeSource: "ROS2" (see https://tier4.github.io/AWSIM/Components/Clock/ClockPublisher/).

[mohamedleithy]

The ROS2 clock system primarily relies on the system time by default since the use_sim_time parameter is not configured. Normally this parameter can be set either through launch files or via ROS2 launch commands (e.g., ros2 run your_package your_node --ros-args -p use_sim_time:=true). In the source code particularly in ROS2TimeSource.cs, there's this comment

// Create clock which uses system time by default (unless use_sim_time is set in ros2). However, I'm not sure how to set this parameter through the Ros2ForUnity package.

[maxime-clem]

You are right and I also cannot find how to set use_sim_time. Maybe the feature is missing from Ros2ForUnity 🤔