Task 0 — Bonus

Bonus Task

Time to Shine Brighter

Mission Brief

The battlefield needs a steady patrol route — and you are in charge of programming it. Your mission is to make the Turtlesim turtle navigate in a perfect square, using a ROS 2 subscriber node to follow goal points published by our command node.

You will:

Create your own ROS 2 workspace
Build a package containing both a goal publisher (given) and your goal follower (to be implemented)
Command the turtle to move from point to point using proportional control

Task Components

Executable Provided:
goal_publisher.py — Publishes four goal points (square vertices) on the /goal topic. The next goal is published only after the turtle reaches the current one.
Your Task: Implement go_to_goal.py that:
- Subscribes to /goal to receive the next goal position (geometry_msgs/msg/Point)
- Moves the turtle toward the goal using proportional control (linear & angular velocities)
- Publishes the turtle’s current pose to /turtle1/goal_status when the goal is reached
Node Functionality:
- Continuously receive and move to each goal until the square path is complete
- Use /turtle1/cmd_vel to send velocity commands
- Use /turtle1/pose to read the turtle’s current position

Procedure

Create Workspace Open a terminal and create a new ROS 2 workspace named hb_ws:
Terminal window
```
mkdir -p ~/hb_ws/src
cd ~/hb_ws/src
```
Create Python Package Inside hb_ws/src, create a new package named bonus_task:
Terminal window
```
ros2 pkg create --build-type ament_python bonus_task
```
This will generate the basic package structure.
Add Python Files Inside the bonus_task/bonus_task/ directory:
- Download the files from here.
- Extract the downloaded file and place it inside the bonus_task folder. Kindly check the package structure mentioned below to avoid any confusion
- Ensure there’s an init.py file (can be empty)
- Add:
  - goal_publisher.py (provided by us)
  - go_to_goal.py- Complete your script go_to_goal.py and then run it to draw the square as given in the picture below.
Your package structure should look like this:
Terminal window
```
hb_ws/
└── src/
  └── bonus_task/
    ├── bonus_task/
    │   ├── __init__.py
    │   ├── goal_publisher.py
    │   └── go_to_goal.py
    ├── package.xml
    ├── setup.cfg
    └── setup.py
```
Edit setup.py To run both files with ros2 run, edit the setup.py so it contains:
Terminal window
```
entry_points={
  'console_scripts': [
    'goal_publisher = bonus_task.goal_publisher:main',
    'go_to_goal = bonus_task.go_to_goal:main',
  ],
},
```
Replace main with the actual function name that starts your node in each file.
Build the Workspace From the root of your workspace:
Terminal window
```
cd ~/hb_ws
colcon build
```
Source the workspace:
Terminal window
```
source install/setup.bash
```

Run the Simulation

Start Turtlesim
Terminal window
```
ros2 run turtlesim turtlesim_node
```

Run Goal Publisher in a new terminal:

cd ~/hb_ws
source install/setup.bash
ros2 run bonus_task goal_publisher

Run Your Subscriber in another terminal:

cd ~/hb_ws
source install/setup.bash
ros2 run bonus_task go_to_goal

Expected Output

The expected square patrol path traced by the turtle.