If the controller configuration is ready, we can build a launch file that starts all
the controllers along with the Gazebo simulation. Navigate to chapter_3_code/seven_dof_arm_gazebo/launch and open the seven_dof_arm_gazebo_control.launch file:

<launch> 
  <!-- Launch Gazebo  --> 
  <include file="$(find seven_dof_arm_gazebo)/launch/seven_dof_arm_world.launch" />    
 
 
  <!-- Load joint controller configurations from YAML file to parameter server --> 
  <rosparam file="$(find seven_dof_arm_gazebo)/config/seven_dof_arm_gazebo_control.yaml" command="load"/> 
 
 
  <!-- load the controllers --> 
  <node name="controller_spawner" pkg="controller_manager" type="spawner" respawn="false" 
  output="screen" ns="/seven_dof_arm" args="joint_state_controller 
            joint1_position_controller 
            joint2_position_controller 
            joint3_position_controller 
            joint4_position_controller 
            joint5_position_controller 
            joint6_position_controller 
            joint7_position_controller"/> 
 
 
  <!-- convert joint states to TF transforms for rviz, etc --> 
  <node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" 
  respawn="false" output="screen"> 
    <remap from="/joint_states" to="/seven_dof_arm/joint_states" /> 
  </node> 
 
</launch> 

The launch files start the Gazebo simulation of the arm, load the controller configuration, load the joint state controller and joint position controllers, and at last, it runs the robot state publisher, which publishes the joint states and TF.

Let's check the controller topics generated after running this launch file:

    $ roslaunch seven_dof_arm_gazebo seven_dof_arm_gazebo_control.launch

If the command is successful, we can see these messages in the terminal:

Here are the topics generated from the controllers when we run this launch file:

    $ rostopic list