This package includes 3 subpackages: kelsey_topics, kelsey_actions, kelsey_services, along with their corresponding launch files. kelsey_topics contains message and topic publisher and subscriber nodes under the names message_publisher.py, message_subscriber.py, topic_publisher.py, and topic_subscriber.py which allows nodes to communicate by publishing (speaking), and subscribing (listening). This package also includes a custom message description--Complex.msg--for messages containing real and imaginary numbers. kelsey_actions is where subpackages that ask nodes to actually DO things would live. Currently, the only action is Timer.action, which waits a certain amount of time, keeps track of the total actual wait time and total number of feedback updates sent, and prints time elapsed and time remaining as feedback on each time step (note that this is different from a service since it provides feedback during execution). kelsey_services includes subpackages where one node provides a function to the other nodes. Currently the only service file in there is WordCount.srv, which counts words.
This system will work on Linux based machines running Ubuntu Bionic 18.04.4, ROS Melodic Morenia, and Python 2.
Once your machine is setup with ROS Melodic Morenia, Python 2, and git, fork and clone this repository from a terminal window in your machine, into a ROS workspace's src directory. Then, navigate to your workspace root, and build the workspace using catkin_make. Then, source the workspace using source devel/setup.bash. You can generally launch the desired subpackage using the format roslaunch <name of subpackage> <launch file name>.
tolaunch the kelsey_actions subpackage, use roslaunch kelsey_actions fancy_action.launch.
To launch the kelsey_services subpackage you will need a message to count the words of. This launch command will be of the form roslaunch kelsey_services fancy_service.launch <enter your own message here>.
kelsey_topics has 2 launch files that need to be launched. After building and sourcing the workspace, the first launch package will be launched using the command roslaunch kelsey_topics fancy_topic_publisher.launch. Then, open a clean terminal window, buils and source your workspace and launch the second launch file using roslaunch kelsey_topcs fancy_topic_subscriber.launch.
Thanks to the launch files on each subpackage, it is straightfoward to get started. Following the instructions in the Installation and Configuration section will launch the desired subpackage.
Launching the kelsey_actions package will activate the server and client nodes. You will see the time elapsed counter and the time remaining counter report about every second until 5 updates are sent.
Launching the kelsey_services package will activate the server and client nodes. You will also need to include a message (as described in the Installation and Configuration) for the counter to evaluate the number of words in the message. The output should be the number of words in the message you typed in.
Launching the kelsey_topics package will print out real and imaginary numbers that are randomly generated, and rinted to the console at 2 Hz.
Additional dependencies can be added by editing package.xml. If you would like to add additional node files, be sure to make them user-executable by using the command chmod u+x in the terminal window after creating the file, and edit the launch file for that subpackage appropriately. This package is derived from the book Programming Robots with ROS: A Practical Introduction to the Robot Operating System by Morgan Quigley, Brian Gerkey, and William Smart (O’Reilly Media, 2015). Information on how to create these packages yourself can be found at http://ricopic.one/courses/robotics_mini_course/ in both print and YouTube videos by Dr. Rico Picone. A great resource for additional information on getting started with ROS can be found at https://risc.readthedocs.io/1-ros-basics.html.
For further questions, please contact the maintainer and sole contributer of this package, Kelsey Buckles at [email protected].