Goals

The goals for this lab are to:

• Get comfortable with creating, and working with, ROS2 packages.
• Gain experience with submitting code through GitHub Classroom.
• Gain experience creating git repositories and committing changes.

Deliverables

By the end of this Lab you will need to:

• Create a properly-formatted ROS 2 Python package.
• Integrate your wander code from the previous lab into that package.
• Modify your code so that it conforms to Python and ROS 2 coding standards.
• Create a git repository to store your work (with commits by at least two group members).

Log into GitHub

This time, when you execute the ros2_jmu_setup.sh script you should go through the process of logging into GitHub. Otherwise you won’t be able to clone or push your repository.

Creating and Building a ROS2 Package

1. First, cd into ~/dev_ws/src.

   cd ~/dev_ws/src/

2. Now create the package:

   ros2 pkg create --build-type ament_python --node-name wander_node wander

   This will populate the wander folder with a properly-formatted ROS2 Python package.

3. If you look inside your wander folder, you should now see the following initial layout:

   wander/                          <-- Folder name matches package name
        package.xml                  <-- ROS2 package information
        setup.cfg                    <-- Python package installation config file
        setup.py                     <-- Python package installation script
        resource/                    <-- Honestly... I'm not sure
            wander
        test/
            test_flake8.py           <-- Tests for Python PEP8 formatting
            test_pep257.py           <-- Tests for docstrings
            test_copyright.py        <-- Test that a copyright is provided
        wander/                      <-- Python package source
            __init__.py              <-- Turns the folder into a Python package
            wander_node.py           <-- Python executable

4. Build your newly created package by changing into your workspace directory and typing:

   colcon build --symlink-install

   Once this command completes, there should be build, install and log directories alongside the existing src directory. Type the following command into the terminal:

   source install/setup.bash

   This command configures your environment so that the ROS 2 system is aware of your newly created package.

   You should now be able to interact with your package using ROS 2 command line tools:

   $ ros2 run wander wander_node 
    Hi from wander.

Congratulations! You now have a fully-functional, properly built, ROS 2 package.

Creating a GitHub Repository

• Copy the URL for the assignment invitation from the course Piazza page. Paste the URL into your browser window and follow the link.

• Click on the link to access the GitHub page for your repository.

• Follow the instructions to select a team name for this assignment. Your team name should have the format wander_name1_name2 where name1 and name2 are the last names of the team members. You should see a page with some text like the following:

   Your team’s assignment repository has been created:
            https://github.com/JMU-CS354-F22/wander-wander_name1_name2
   

• Complete the following steps in order to add your package to a new git repository. Don’t just copy and paste the instructions below! Make sure you understand the meaning of each step. (GIT_URL should be replaced with the URL for your GitHub project. It should look something like: https://github.com/JMU-CS354-F23/wander-wander_name1_name2)

  cd ~/dev_ws/src/wander
   git init
   echo "# Packaging Lab" >> README.md
   git add *
   git commit -m "first commit"
   git branch -M main
   git remote add origin GIT_URL
   git push -u origin main

• Reload your repository in GitHub to confirm that your package has been pushed correctly.

Congratulations! You have a git repository on GitHub.

Adding Functionality

At this point you should log out and log back in and SOMEONE ELSE from your group should clone the repository and make the changes described below. Full credit for the lab will require commits from multiple group members.

Note that if you clone the package like this:

git clone GIT_URL

The folder will have the same name as the GitHub repository.

If you clone it like this:

git clone GIT_URL wander

Then the folder name will match the package name, which will be less confusing. Once the repository is cloned into ~/dev_ws/src complete the steps below.

• Copy the contents of your wander.py solution from the previous lab into wander_node.py. Rebuild your package and test that you can use ros2 node run to execute your new node:

  ros2 launch turtlebot3_gazebo  turtlebot3_world.launch.py

  In a separate terminal:

  ros2 run wander wander_node

• Copy your forward.py solution form the last lab into a file named forward_node.py. Update setup.py so that it recognizes forward_node as an entry point, rebuild, and test the result:

  ros2 run wander forward_node

Tidying Up

You can check style issues by running flake8 in the folder containing your Python code. For example:

python -m flake8 --max-line-length 100

Fix as many style errors as possible.

Saving Your Work

Once you are satisfied with your package, commit your work, and push it back to GitHub by completing the following steps:

• Change into your package folder and type:

  git add *

  to add all of your newly created files to the repository.

• Commit your changes by typing:

  git commit -m 'Added wander code. Fixed style issues.'

  Every time you commit your code you MUST provide a reasonably informative commit message.

• Push your changes

  git push

  Your changes are not safe until you complete this step! Once you have completed the previous step, test that everything is OK by accessing your repository through the GitHub web interface. You should be able to see the files you’ve pushed.

Submitting

There is nothing to submit for this lab. I’ll check your work through GitHub.

If You Have Extra Time

Modify your wander_node.py solution (or mine) so that the wandering is random. Rather than turning until the obstacle is out of range, turn by some randomly determined angle. Push your changes to the GitHub repository.

You may also want to improve the avoidance logic so that the obstacle detection takes into account the width of the robot.