Before creating the URDF file for the robot, let's create a ROS package in the catkin workspace so that the robot model keeps using the following command:

    $ catkin_create_pkg mastering_ros_robot_description_pkg roscpp tf 
 geometry_msgs urdf rviz xacro 
  

The package mainly depends on the urdf and xacro packages, and we can create the urdf file of the robot inside this package and create launch files to display the created urdf in RViz. The full package is available on the following Git repository, you can clone the repository for a reference to implement this package or you can
get the package from the section's source code:

    $ git clone 
 https://github.com/qboticslabs/mastering_ros_robot_description_pkg.git
  

Before creating the urdf file for this robot, let's create three folders called urdf, meshes, and launch inside the package folder. The urdf folder can be used to
keep the urdf/xacro files that we are going to create. The meshes folder keeps the meshes that we need to include in the urdf file and the launch folder keeps the ROS launch files.