After adding the differential drive plugin, we need to joint state publishers to the existing launch file, or we can build a new one. You can see the new final launch file: diff_wheeled_gazebo_full.launch from chapter_3_code/diff_wheeled_robot_gazebo/launch.

The launch file contains joint state publishers, which help to visualize in RViz. Here are the extra lines added in this launch file for the joint state publishing:

  <node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>  
  <!-- start robot state publisher --> 
  <node pkg="robot_state_publisher" type="state_publisher" name="robot_state_publisher" output="screen" > 
    <param name="publish_frequency" type="double" value="50.0" /> 
  </node>