例如加载turtlebot机器人launch文件如下:(在gazebo仿真中最后都是通过这种方式加载xacro文件的)
<launch>
<arg name="base"/>
<arg name="stacks"/>
<arg name="3d_sensor"/>
<arg name="urdf_file" default="$(find xacro)/xacro.py '$(find turtlebot_description)/robots/$(arg base)_$(arg stacks)_$(arg 3d_sensor).urdf.xacro'"/>
<param name="robot_description" command="$(arg urdf_file)"/>
<!-- Gazebo model spawner -->
<node name="spawn_turtlebot_model" pkg="gazebo_ros" type="spawn_model"
args="$(optenv ROBOT_INITIAL_POSE) -unpause -urdf -param robot_description -model mobile_base -P 1 "/>
<!-- Velocity muxer -->
<node pkg="nodelet" type="nodelet" name="mobile_base_nodelet_manager" args="manager"/>
<node pkg="no