Lesson 10: Introduction to RQT

You will learn a ros debug tool — RQT

rqt is a Qt-based framework within the Robot Operating System (ROS) that provides a collection of graphical tools for visualization and debugging in a modular and flexible manner. It serves as a unified interface for monitoring and interacting with various aspects of a ROS-based robotic system.

Key Features of rqt:

1. Modular Design:

   - Plugins: rqt is built around a plugin system, where different tools (called plugins) can be loaded, unloaded, and customized according to the user’s needs. This modular approach allows users to tailor the interface to their specific requirements.

2. Graphical User Interface (GUI) Tools:

   - rqt provides a variety of GUI tools for different tasks, such as plotting data, visualizing node graphs, managing parameters, and more. These tools help developers interact with the robot's software in a more intuitive way.

3. Data Visualization:

   -rqt_plot: A plugin for plotting real-time data from ROS topics. It’s useful for visualizing sensor readings, control signals, and other numeric data.

   - rqt_bag: Allows users to view and analyze ROS bag files, which are recordings of ROS topic data, enabling post-analysis of sensor data and system performance.

4. ROS Node Management:

   - rqt_graph: Visualizes the communication between ROS nodes, showing the flow of messages between topics and services. This is crucial for understanding the architecture and debugging communication issues in a ROS system.

   - rqt_console: Provides a centralized view of log messages, helping to monitor the status of nodes and diagnose errors or warnings.

5. Parameter Management:

   - rqt_reconfigure: Allows dynamic reconfiguration of ROS parameters at runtime, providing a way to adjust system settings on the fly without restarting nodes.

6. System Monitoring:

   - rqt_top: Displays CPU, memory, and network usage by ROS nodes, similar to the Unix `top` command, helping in resource management and performance monitoring.

7. Integration with Other ROS Tools:

   - rqt can be used alongside other ROS tools like RViz, Gazebo, and tf2, providing a more comprehensive development and debugging environment.

Common Use Cases:

- Debugging and Monitoring:

  - rqt is invaluable for real-time monitoring of a running ROS system. By visualizing node connections, plotting sensor data, and examining log messages, developers can quickly identify and resolve issues.

- System Configuration:

  - With rqt, developers can adjust system parameters dynamically during runtime, allowing for fine-tuning and optimization of the robot’s behavior without the need for recompilation or node restarts.

- Data Analysis:

  - rqt_bag and rqt_plot are useful for post-processing recorded data, helping developers understand system performance and sensor readings during specific events or test runs.

- Visualization of System Architecture:

  - rqt_graph helps in visualizing the entire ROS node network, making it easier to understand and document the system architecture.

Example Usage:

- Starting rqt:

  Run the following command in ROS 2

  rosrun rqt_gui rqt_gui

  This command launches the rqt framework, and you can start adding or removing plugins as needed.

- Adding Plugins:

  - Once rqt is running, you can add plugins via the "Plugins" menu. For example, to add the plot tool:

    Plugins -> Visualization -> Plot

- Custom Workspaces:

  - rqt allows you to save and load workspaces, which are configurations of plugins and their layouts. This is useful for quickly setting up a development environment tailored to specific tasks or projects.

In summary, rqt is a powerful and flexible toolset in ROS that enhances the development, debugging, and monitoring of robotic systems by providing a rich set of graphical interfaces and tools.

rqt_console:

rqt_console is a GUI tool for inspecting log messages in ROS 2. While log messages typically appear in the terminal, rqt_console allows you to collect, organize, and closely analyze them over time. You can filter messages, save them for future review, and reload saved logs to introspect at a later time, providing a more structured approach to log management.

For more information regarding rqt_console, visit the below tutorial:

https://docs.ros.org/en/humble/Tutorials/Beginner-CLI-Tools/Using-Rqt-Console/Using-Rqt-Console.html