How do you troubleshoot your robot system with ROS logging?

1 What is ROS logging?

ROS logging is a feature of ROS that allows you to generate and consume messages from various sources in your robot system. These messages can include information, warnings, errors, or debugging data that can help you understand what is happening in your system and identify potential problems. ROS logging uses the rosconsole package, which is based on the log4cxx library, to provide a standard interface for logging in C++ and Python nodes. You can also use other tools, such as rqt_console, rqt_logger_level, or rosbag, to view, modify, or record the log messages.

2 How to use ROS logging in your code?

To use ROS logging in your code, you need to include the rosconsole header file in C++ or import the rospy module in Python. Then, you can use the predefined macros or functions to generate log messages with different levels and names. For example, in C++, you can use ROS_INFO, ROS_WARN, ROS_ERROR, or ROS_DEBUG to log messages with different severities. In Python, you can use rospy.loginfo, rospy.logwarn, rospy.logerr, or rospy.logdebug for the same purpose. You can also specify the name of the node or logger that generates the message, which can be useful for filtering or grouping the messages later.

4 How to record and replay ROS log messages?

Sometimes, you may want to record and replay ROS log messages for later analysis or debugging. For this purpose, you can use the tool rosbag, which allows you to capture and store the messages from any topics in your system in a file called a bag. You can then use rosbag play to replay the messages from the bag file as if they were generated by the original nodes. You can also use rosbag filter to extract only the messages that match certain criteria from the bag file. You can also use other tools, such as rqt_bag or rosbag info, to inspect or visualize the contents of the bag file.

5 How to analyze ROS log messages?

Once you have recorded or viewed the ROS log messages, you may want to analyze them to find patterns, trends, or anomalies in your system's behavior or performance. There are different ways to analyze ROS log messages, depending on the type and amount of data you have. One of the simplest ways is to use the command-line tool grep to search for specific keywords or expressions in the messages. You can also use other tools, such as awk, sed, or cut, to manipulate or extract the data from the messages. Another way to analyze ROS log messages is to use the graphical tool rqt_plot, which allows you to plot the numerical values from the messages over time. You can also use other tools, such as matplotlib, pandas, or numpy, to perform more advanced statistical or graphical analysis on the data.

6 How to improve ROS logging?

ROS logging is a powerful and flexible feature that can help you troubleshoot your robot system, but it can also be improved in some aspects. For example, you may want to add more context or metadata to your log messages, such as timestamps, locations, or parameters. You may also want to customize the format or output of your log messages, such as color, font, or destination. You may also want to integrate your log messages with other systems or platforms, such as databases, web servers, or cloud services. For these purposes, you can use some of the existing packages or tools that extend or enhance ROS logging, such as rosgraph_msgs, rosout_agg, rosbridge_server, or rosserial. You can also create your own packages or tools that suit your specific needs and preferences.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?