Understanding urdf_spawn.launch

Course Support URDF for Robot Modeling
1 
<?xml version="1.0" encoding="UTF-8"?>

<launch>

    <arg name="x" default="0.0" />
    <arg name="y" default="0.0" />
    <arg name="z" default="0.0" />

    <arg name="urdf_robot_file" default="" />
    <arg name="robot_name" default="" />

    <!-- This Version was created due to some errors seen in the V1 that crashed GAzebo or went too slow in spawn -->
    <!-- Load the URDF into the ROS Parameter Server -->
    <param name="robot_description" command="cat $(arg urdf_robot_file)" />

    <!-- Run a python script to the send a service call to gazebo_ros to spawn a URDF robot -->
    <node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
    args="-urdf -x $(arg x) -y $(arg y) -z $(arg z)  -model $(arg robot_name) -param robot_description"/>
</launch>

In the urdf_spawn.launch file, what does it truly mean with the syntax:

<arg name="x" value="0.0"/>

Is it the position of the robot or something else?

Also, in this part of the code;

 <node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
    args="-urdf -x $(arg x) -y $(arg y) -z $(arg z)  -model $(arg robot_name) -param robot_description"/>

What does each -urdf -x -y -z -model etc. actually do? Is there a more intuitive way to explain this?

2

Hello @WhenOwlsHoot ,

The [x, y, z] values represent the coordinates in the world where you want to spawn the robot. How it is right now, the robot will spawn in the coordinates [0, 0 , 0] of the world (the center).