Add ROS2 package low_cost_robot_description for follower arm URDF

.gitignore

@@ -1,3 +1,8 @@
 .idea/
 .DS_Store
 __pycache__/
+
+# For ROS 2 workspace
+ros2_ws/build
+ros2_ws/log
+ros2_ws/install

ros2_ws/README.md

@@ -0,0 +1,64 @@
+# ros2_ws
+
+## About
+- This workspace is a directory containing the `ROS 2` packages for the `low_cost_robot` project.  
+- Before using these `ROS 2` packages, it’s necessary to source the `ROS 2` installation for this workspace in the terminal where you plan to work.  
+- Since `ROS 2` is more natively supported on the `Ubuntu` platform, all instructions and commands in the `README.md` under the `ros2_ws` directory are for Ubuntu. If you use the `MacOS` platform, instructions and commands may be different.
+
+## `ROS 2` Package List in This Workspace
+1. [**low_cost_robot_description**](./src/low_cost_robot_description/README.md): This package is for the URDF of the robot arm (follower).
+
+## Prerequisites
+1. `ROS 2` installed (You can refer to this [document](https://docs.ros.org/en/humble/Installation.html) to install `ROS 2` Humble Hawksbill or another `ROS 2` [distribution](https://docs.ros.org/en/humble/Releases.html).)
+2. `colcon` installed (You can refer to this [document](https://docs.ros.org/en/humble/Tutorials/Beginner-Client-Libraries/Colcon-Tutorial.html) to install `colcon`.)
+3. `rosdep` installed (You can refer to this [document](https://docs.ros.org/en/humble/Tutorials/Intermediate/Rosdep.html) to install `rosdep`.)
+
+
+## Installation
+1. Source the ROS 2 setup files ([reference](https://docs.ros.org/en/humble/Tutorials/Beginner-CLI-Tools/Configuring-ROS2-Environment.html#id4)):
+   ```shell
+   # Replace ".bash" with your shell if you're not using bash
+   # Possible values are: setup.bash, setup.sh, setup.zsh
+   # Replace "humble" with your ROS 2 distribution if you're not using "ROS 2 Humble Hawksbill"
+   source /opt/ros/humble/setup.bash
+   ```
+2. Change directory to `ros2_ws` and install the dependencies by `rosdep` of `ROS 2` packages ([reference](https://docs.ros.org/en/humble/Tutorials/Intermediate/Rosdep.html)):
+   ```shell
+   # Assume the current directory is `low_cost_robot`
+   cd ros2_ws
+
+   # `--ignore-src` means to ignore installing dependencies
+   # Use `rosdep -h` to get help
+   rosdep install --from-paths src -y --ignore-src
+   ```
+3. Build the workspace by `colcon` ([reference](https://docs.ros.org/en/humble/Tutorials/Beginner-Client-Libraries/Colcon-Tutorial.html)):
+   ```shell
+   # The option `--symlink-install` allows the installed files to be changed by
+   # changing the files in the source space (e.g. Python files or other non-compiled resources)
+   # for faster iteration.
+   colcon build --symlink-install
+   ```
+
+4. Source the installation of this workspace ([reference](https://docs.ros.org/en/humble/Tutorials/Beginner-Client-Libraries/Creating-A-Workspace/Creating-A-Workspace.html)):
+   ```shell
+   # Assume the current directory is `low_cost_robot`
+   # Replace ".bash" with your shell if you're not using bash
+   # Possible values are: local_setup.bash, local_setup.sh, local_setup.zsh
+   source install/local_setup.bash
+   ```
+
+- > Notice:  
+   > Normally, you need to source the ROS 2 setup files and the installation of this workspace after opening the terminal:
+   > ```shell
+   > # Replace ".bash" with your shell if you're not using bash
+   > # Possible values are: setup.bash, setup.sh, setup.zsh
+   > # Replace "humble" with your ROS 2 distribution if you're not using "ROS 2 Humble Hawksbill"
+   > source /opt/ros/humble/setup.bash
+   >
+   > # Assume the current directory is `low_cost_robot`
+   > cd ros2_ws
+   >
+   > # Replace ".bash" with your shell if you're not using bash
+   > # Possible values are: local_setup.bash, local_setup.sh, local_setup.zsh
+   > source install/local_setup.bash
+   > ```