RQT Visualisation

One of the most powerful and versatile tools in ROS is RQT (ROS Qt-based Graphical User Interface Tools).

What is RQT?

RQT is an integral part of the Robot Operating System (ROS) ecosystem, designed to facilitate the interaction, visualization, and analysis of ROS-based robotics systems. As a collection of graphical user interface (GUI) plugins, RQT leverages the power of the Qt framework, a versatile, cross-platform toolkit for creating complex and robust GUIs.

Key Features and Capabilities of RQT

  • Visualization

    • RQT Plot: A plugin for plotting data in real-time, useful for monitoring sensor data, robot states, and other variables.
    • RQT Graph: This visualizes the computational graph of ROS nodes and the communication between them, helping developers understand the flow of data and interactions within the system.
    • RQT Image View: A tool for displaying image data from cameras or other imaging sensors in real-time, which is critical for tasks like computer vision and navigation.

  • Analysis

    • RQT Console: Provides a logging interface where users can view and filter log messages from different nodes, facilitating debugging and performance monitoring.
    • RQT Bag: Allows users to play back and analyze data from ROS bag files, which are used to record and store ROS message data for offline analysis and testing.

  • Interaction

    • RQT Reconfigure: Enables dynamic reconfiguration of parameters in ROS nodes without restarting them, allowing for real-time tuning and adjustments.
    • RQT Service Caller: Provides an interface for calling ROS services, making it easier to interact with service servers directly from a GUI.

‍How to install rqt plugin

sudo apt install ros-humble-rqt ros-humble-rqt-common-plugins

Verify Installation:

After installation, you can verify it by running RQT:

source /opt/ros/humble/setup.bash
rqt

This should open the RQT graphical interface. If it opens without errors, the installation was successful.

useful plugins include:

1. rqt_graph

rqt_graph visualizes the ROS computation graph, showing nodes and the topics they publish and subscribe to.

usage

  • Launch rqt_graph from the terminal:
rqt_graph

Features:

  • The graph will display active nodes and their connections. It helps in understanding the communication flow between different parts of your system.
  • Dynamic updates as nodes and topics change.
  • Filtering options to focus on specific parts of the graph.

2. rqt_console

rqt_console provides a graphical view of ROS log messages, allowing you to filter and analyze them more easily than with the standard console output.

Usage:

  • Launch rqt_console from the terminal:
rqt_console

Features:

  • The console displays log messages categorized by severity (DEBUG, INFO, WARN, ERROR, FATAL).
  • Filtering based on node, severity, and message content.
  • Pause and resume log display.
  • Save log messages to a file for later analysis.

3. rqt_plot

  • rqt_plot plots numeric values from ROS topics in real-time, providing a graphical representation of sensor data, control signals, or other numerical information.

Usage:

  • Launch rqt_plot from the terminal:
rqt_plot
  • Enter the topic names you want to plot.

add image

Features:

  • Supports multiple plots and multiple topics per plot.
  • Customizable axes and scales.
  • Useful for monitoring real-time data trends.

4. rqt_image_view

rqt_image_view displays images from ROS topics, useful for monitoring camera feeds or processed images.

Usage:

  • Launch rqt_image_view from the terminal:
rqt_image_view
  • Select the image topic you want to display.

add image

Features:

  • Real-time display of image streams.
  • Supports different image formats and encoding types.
  • Adjustable display settings like zoom and rotation.

5. rqt_tf_tree

rqt_tf_tree visualizes the TF (transform) tree, showing the relationship between coordinate frames in ROS.

Usage:

  • Launch rqt_tf_tree from the terminal: 
rqt_tf_tree
  • View the hierarchical relationship between frames.

Features:

  • Dynamic updates as the TF tree changes.
  • Useful for understanding the spatial relationships in robotic systems.

Conclusion

RQT enhances the ROS experience by bringing the convenience and efficiency of GUIs to the robotics development workflow. By utilizing the Qt framework, RQT offers a powerful and flexible platform for visualization, analysis, and interaction, making it an indispensable tool for developers, researchers, and operators working with ROS-enabled robots and systems. Its ability to simplify complex tasks, provide real-time feedback, and integrate seamlessly with other ROS components underscores its importance in the field of robotics.