RobotnixAcademy

Unit 03 · lesson

See the Graph With `rqt_graph`

See the Graph With rqt_graph

CLI output is precise. A graph can make relationships easier to see.

With Turtlesim and teleop running, launch:

rqt_graph

or, as the topic tutorial demonstrates:

ros2 run rqt_graph rqt_graph

Read the picture as a system model

You should be able to identify the Turtlesim and teleop nodes and the topic connecting movement commands between them.

Do not treat the graph like decoration.

Use this translation:

NODE A -- publishes --> TOPIC -- delivered to --> NODE B subscriber
Diagram showing the teleop node publishing to the turtle command topic and the Turtlesim node subscribing to it.
Diagram showing the teleop node publishing to the turtle command topic and the Turtlesim node subscribing to it.

Diagrams open at a readable shape-aware scale. Zoom or expand when you need more detail.

Cross-check with the CLI

Run:

ros2 node list
ros2 node info /turtlesim
ros2 node info /teleop_turtle
ros2 topic list

Pick one edge visible in rqt_graph and prove the same relationship from CLI evidence.

Why filters matter

rqt_graph can hide infrastructure/debug elements to make a beginner graph readable. Changing a filter does not change the ROS system. It changes only what the visualization displays.

That distinction is easy to forget.

Screenshot evidence

If screenshots are allowed in your course environment, capture the graph and annotate:

  • node names;
  • topic name;
  • publish direction;
  • subscribe direction.

If screenshots are not available, draw the same relationship as text.

Checkpoint

Write one sentence beginning:

The graph shows...

and a second beginning:

The CLI confirms this because...