ROS2 Basics in 5 days (Python): What is the name of the velocity topic for the robot & How to publish to velocity topic of the robot?

What is the name of the velocity topic for ROS2 Basics in 5 days? I ran the command ‘ros2 topic list’ but could not find the cmd_vel topic.

How do I publish to the velocity topic of the robot? I am unable to find the cmd_vel topic in the rosject Section 1, 1.1 Wall following behaviour.

Hi, welcome to the community!

The topic is called /cmd_vel. Have you launched the simulation and the ros1_bridge as specified in the instructions?

Hi!

Yes, I have launched the simulation and the ros1_bridge as specified in the instructions. I could see the /scan topic for LaserScan but not the /cmd_vel topic when I ran the command ros2 topic list.

How do I solve this problem?

Thank you

That’s because you haven’t established the connection for that topic since nothing is being published.
Try publishing from ROS2:


ros2 topic pub --rate 10 /cmd_vel geometry_msgs/msg/Twist \"{linear: {x: 0.0, y: 0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 0.2}}\"

It’s working now, I’m so new to this. Thanks so much for your help.

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