5.3.1 A basic introduction to tf2_ros

Course subject(s) Module 5. Robot Vision

In this lecture, the basics of TF and the actual functionality of the tf2_ros package will be explained.

tf2_ros package

  • Implements functional aspects, and actively maintain relations.
  • Transform pose: allows for “time travel” – look up the spatiotemporal relation.

Was there a TF (1) package?

  • Yes
      • Used in many applications
      • Command line tools
      • All in one (vs clear separation in TF2)
  • All TF functionalities are migrated to tf2_ros
      • Availability of a transform buffer in tf2_ros.

Information representation:

  • Quantification
      • 3D transformation.
      • ROS topic: /tf (tf2_msgs/TFMessage)

Command line tools:

  • Print transformation
    $ rosrun tf tf_echo <source_frame> <target_frame>
  • View the “TF tree”
    $ rosrun tf view_frames
    $ rosrun rf2_tools view_frames.py
  • Publish a static transform
    $ rosrun tf2_ros static_transform_publisher <trans> <rot> "parent" "child"
  • tf_echo (static and dynamic)

tf_echo (static)

  • Query transform that never moves in our environment.
  • Prints latest information with 1Hz.
  • Fixed with each other (equal times).
  • Outputs translation and quaternion .
Creative Commons License
Hello (Real) World with ROS - Robot Operating System by TU Delft OpenCourseWare is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work at https://online-learning.tudelft.nl/courses/hello-real-world-with-ros-robot-operating-systems//.
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