Ros2 learning notes (VII) tools for learning ros2 from turnlesim

Preface

Study ROS2 Way , Not through learning ROS1 Instead of , because ROS2 Of “ kernel ” differ ROS1, We must seriously start from scratch and learn again .

Ubuntu edition ：20.04

ROS edition ：Foxy

Review of study notes

• ROS2 Learning notes ( One ) Get document
• ubuntu20.04 install ROS2 and ROS1 coexistence
• ROS2 Learning notes ( Two ) from turtlesim Study ROS2 node
• ROS2 Learning notes ( 3、 ... and ) from turtlesim Study ROS2 The theme
• ROS2 Learning notes ( Four ) from turtlesim Study ROS2 service
• ROS2 Learning notes ( 5、 ... and ) from turtlesim Study ROS2 Parameters
• ROS2 Learning notes ( 6、 ... and ) from turtlesim Study ROS2 action

1.rqt_console Tools

rqt_console It's a graphical tool , For viewing ROS2 Log messages in . In general , All log messages will be refreshed in the terminal . By using rqt_console Tools , You can collect log messages more clearly , More conditioning to view and save logs , And you can play back the saved file data .

2. start-up rqt_console Tools

$ ros2 run rqt_console rqt_console

The interface is as follows ：

The interface is divided into three boxes , The above section is used to display log messages in the system .

The middle part is used to select the severity level to filter log messages . You can also add more filters through the plus sign on the right .

The following section is used to highlight the log message containing the string I entered .

3. Start the little turtle Simulator

$ ros2 run turtlesim turtlesim_node

4. Send instructions for turtle movement

Now we send the movement instructions to the turtle , Let the turtle hit the boundary of the simulator , This generates log messages .

$ ros2 topic pub -r 1 /turtle1/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 2.0, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: 0.0}}"

After sending the command , The little turtle will keep hitting the wall , This will receive... At a steady rate Warn Log information ：

Turn off the sending command terminal .

5. Log severity level

ROS2 Your log has a severity rating ：

Fatal   #  Indicates that the system will terminate , To prevent yourself from being hurt 
Error   #  Indicates that the problem is significant , But it doesn't necessarily damage the system , But it will prevent the program from running 
Warn    #  Indicates a warning problem , There may be unexpected or deeper problems , But it won't completely damage the function 
Info    #  A hint indicating the event message , The system operates as expected 
Debug   #  It shows the whole step-by-step process of system implementation 

6. Set the log default severity

It can be run /turtlesim, By remapping, set the default severity to Warn：

$ ros2 run turtlesim turtlesim_node --ros-args --log-level WARN

At this time , I won't see Info The question of rank , Only Warn More serious problems .

summary

Learn how to use rqt_console View log messages , It can help you locate the problem faster .

Reference:

https://docs.ros.org/en/foxy/Tutorials/Rqt-Console/Using-Rqt-Console.html

Conclusion

This paper is also based on the author's learning and use experience , Strong subjectivity , If there is anything wrong or unclear , Welcome to leave a message in the comments area ~

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