cd ~/catkin_test/src
git clone https://github.com/ros/urdf_sim_tutorial.git

roslaunch urdf_sim_tutorial gazebo.launch 

<launch>

  <!-- these are the arguments you can pass this launch file, for example paused:=true 
这些是你能设定的launch文件的参数 -->
  <arg name="paused" default="false"/>
  <arg name="use_sim_time" default="true"/>
  <arg name="gui" default="true"/>
  <arg name="headless" default="false"/>
  <arg name="debug" default="false"/>
  <arg name="model" default="$(find urdf_tutorial)/urdf/08-macroed.urdf.xacro"/>

  <!-- We resume the logic in empty_world.launch, changing only the name of the world to be launched
我们设定了launch文件的逻辑，只改变了被运行的世界
 -->
  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="debug" value="$(arg debug)" />
    <arg name="gui" value="$(arg gui)" />
    <arg name="paused" value="$(arg paused)"/>
    <arg name="use_sim_time" value="$(arg use_sim_time)"/>
    <arg name="headless" value="$(arg headless)"/>
  </include>

  <param name="robot_description" command="$(find xacro)/xacro.py $(arg model)" />

  <!-- push robot_description to factory and spawn robot in gazebo 
加载urdf文件，并且在gazebo里生成机器人
-->
  <node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model"
        args="-z 1.0 -unpause -urdf -model robot -param robot_description" respawn="false" output="screen" />

  <node pkg="robot_state_publisher" type="robot_state_publisher"  name="robot_state_publisher">
    <param name="publish_frequency" type="double" value="30.0" />
  </node>

</launch>