`tf2`, Unit Testing and Bag Files

ENPM808X - Abhishekh Reddy Munnangi, 119399002

Get started

Environment and dependencies

Operating system, ROS installation and additional software

Ubuntu Jammy (22.04)
ROS2 Humble Hawksbill (Even base installation is sufficient)
Git

Package dependencies

rclcpp - ROS2 C++ Client Library
std_msgs - Standard Messages Library
std_srvs - Standard Services Library
ros2launch - ROS2 Launch Library for Launch file support
tf2 - Package API for working with reference frames and transformations
tf2_ros - Command line tools for using the tf2 package
ament_cmake_gtest - GTest for testing the package

Additional notes and considerations

Frames PDF, rosbag outputs are in the results folder, this folder has been reorganized in this release
Screenshots of the rqt_console GUI showing log messages are in the results/ folder.
The following section assumes that you have an existing ROS2 workspace. If not, see how to create one.

Cloning the repository

The root directory of this repository are contents of a ROS2 package. Hence, this needs to be cloned to a folder in the src/ directory of a ROS2 project workspace.

<Your ROS2 Workspace>/
├── build/
├── install/
├── log/
└── src/
    └── beginner_tutorials/ <-- Repository clones to this folder
        └── <Repository contents>

Workspace directory tree with this repository contents in it

Run this command in the src/ directory of your ROS2 workspace

git clone https://github.com/armgits/beginner_tutorials.git beginner_tutorials

Before the next step: For the first time, ensure that the package dependencies are installed. Run these commands from the root workspace directory.

rosdep init && rosdep update

rosdep install --from-paths src -y --ignore-src

Build the package in the root directory of your ROS2 workspace.

colcon build --packages-select beginner_tutorials

Source the freshly built package

source install/setup.bash

Testing a node

GTest test case has been added in this homework to test the first_astronaut node.

colcon test --packages-select beginner_tutorials

Detailed outputs could be found in the build/beginner_tutorials/Testing and build/beginner_tutorials/test_results folders.

Running the nodes for demonstration

In this exercise, the nodes could either be started individually or together using a launch file.

Running the nodes individually

Start the first_astronaut node in the first terminal

ros2 run beginner_tutorials talker

Start the second_astronaut node in a new, second terminal

ros2 run beginner_tutorials listener

Note: You might need to source the package in the new terminal as well before running the above command

Hit Crtl + C in both the terminals to stop the nodes.

Running the nodes together using launch file (Recommended)

Launch file unifies the above steps into a single line command for convenience.

Both the nodes could be launched together with the desired parameters as arguments, creating the perfect meme template.

ros2 launch beginner_tutorials launch.py record_bag:=<Your option> realization:=<Your text> dramatic_end:=<Your option>

Entry format for arguments:

record_bag:= True/False
realization:= "double quotes"
dramatic_end:= true/false

To learn more about the launch arguments, use this command

ros2 launch beginner_tutorials launch.py --show-args

Recording messages on topics to rosbag

Note: The recorded rosbag will be saved to the current working directory. i.e. The directory in which the launch file is executed in the terminal.

Use the record_bag launch argument in the launch command which accepts a boolean value of True or False to record the message activity to a rosbag.

TF Frames

Two frames world and its child frame talk are broadcasted using a StaticTransformBroadcaster from the tf2 package. They can be checked and viewed while at least the first_astronaut node is running.

Read the stamped transform messages

ros2 run tf2_ros tf2_echo world talk

View the frames in a PDF (File is saved in a similar fashion as recording rosbag)

ros2 run tf2_tools view_frames

See the documentaion for more information.

Reference

This ROS2 package is a template for the "Always has been" meme.

armgits/beginner_tutorials

tf2, Unit Testing and Bag Files