.urdf file to .world file

edit

Hi ahmed charef! I think that you're trying to link your URDF robot model to a world and launch it in gazebo.

If is that case it's explain in gazebo tutorials link, but i'm going to try to explain to you.

In the model.config file

 <?xml version="1.0"?>
  <model>
    <name>MYROBOT</name>
    <version>1.0</version>
    <sdf>urdf/MYROBOT.urdf</sdf> <--- **Here you must specify where is your urdu file** -->
    <author>
      <name>My name</name>
      <email>name@email.address</email>
    </author>
    <description>
      A description of the model
    </description>
  </model>

And then, in the world file you must include it as the rest of things in the world

<?xml version="1.0"?> 
<sdf version="1.4">
  <world name="default">
    <!-- Ground Plane -->
    <include>
        <uri>model://ground_plane</uri>
    </include>
    <include>
        <uri>model://sun</uri>
    </include>
    <!-- Your URDF file -->
    <include>
        <uri>model://MYROBOT</uri>  <!-- The name that you write in the model.config -->
    </include>
  </world>
</sdf>

I hope this can help you.