I cannot let the robot stop =(

I finished Exercise 3.2, and I can run the robot correctly. However, I can not let the robot stop, even , which instruction should I use?

Hi, you could publish an extra zero velocity message at the end of your program. That is, when the robot has performed the desired behavior.

You can try this:

How to stop your robot when ROS is shutting down - Knowledgebase - The Construct ROS Community (robotigniteacademy.com)