I am trying to build a urdf for a complicated robot, i have exported the design using sw2urdf and a package directory "x" is generated then i follow these steps:

1- switch to ubuntu and create a directory " p">> src>> x . 2. cd to "p" and run: catkin_make 3.Source ~/p/devel/Setup .bash 4.Cd launch 5. Roslaunch gazebo.launch

The gazebo open an empty world not including my robot. My questions what is the wrong with my steps? What is the proper method to open my robot in gazeb & rviz? Sw 20 Ubunutu 18.04