We can create the simulation model for a robotic arm by updating the existing robot description by adding simulation parameters.
We can create the package needed to simulate the robotic arm using the following command:
$ catkin_create_pkg seven_dof_arm_gazebo gazebo_msgs gazebo_plugins gazebo_ros gazebo_ros_control mastering_ros_robot_description_pkg
Alternatively, the full package is available in the following Git repository; you can clone the repository for a reference to implement this package, or you can get the package from the book's source code:
$ git clone https://github.com/jocacace/seven_dof_arm_gazebo.git
You can see the complete simulation model of the robot in the seven_dof_arm.xacro file, placed in the mastering_ros_robot_description_pkg/urdf/ folder.
The file is filled with URDF tags, which are necessary...