Question

Hi,

I am trying to spawn SDF model of a human in Gazebo environment. The human sdf model I have got from here. In order to spawn that model in Gazebo, I have created 3 roslaunch files. The first roslaunch file (named start_world.launch) is just to start the empty Gazebo world in ROS which is as below

<?xml version="1.0"?>
 <launch>
    <!-- startup simulated world -->
    <include file="$(find gazebo_ros)/launch/empty_world.launch">
  </include>
</launch>

The second launch file, spawn_sdf.launch, is pertaining to spawning a general sdf model in Gazebo which is as below

<?xml version="1.0"?>
<launch>
  <arg name="x" default="0.0" />
  <arg name="y" default="0.0" />
  <arg name="z" default="0.0" />
  <arg name="roll" default="0.0" />
  <arg name="pitch" default="0.0" />
  <arg name="yaw" default="0.0" />
  <arg name="sdf_robot_file" default="$(find person_sim)/models/model.sdf"/>
  <arg name="robot_name" default="person_standing"/>

  <node name="$(arg robot_name)_spawn_urdf" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen" args="-file $(arg sdf_robot_file) -sdf -x $(arg x) -y $(arg y) -z $(arg z) -R $(arg roll) -P $(arg pitch) -Y $(arg yaw) -model $(arg robot_name)"/>
</launch>

The third roslaunch file, spawn_person.launch, includes the second roslaunch file and presented below

<?xml version="1.0"?>
<launch>
  <arg name="x" default="0.0" />
  <arg name="y" default="0.0" />
  <arg name="z" default="0.0" />
  <arg name="yaw" default="0.0" />
  <arg name="sdf_robot_file" default="$(find person_sim)/models/model.sdf"/>
  <arg name="robot_name" default="person_standing"/>

  <!-- startup simulated world -->
  <include file="$(find person_sim)/launch/spawn_sdf.launch">
      <arg name="sdf_robot_file" value="$(arg sdf_robot_file)"/>
      <arg name="robot_name" value="$(arg robot_name)" />
      <arg name="x" value="1.0" />
      <arg name="y" value="1.0" />
      <arg name="z" value="0.0" />
      <arg name="yaw" value="0.0" />
  </include>
</launch>

In one terminal I launch start_world.launch and in the second terminal I launch spawn_person.launch. Please note that all these launch files and the sdf model reside in a package named person_sim. After running the second launch file in the terminal, I see the following output

$ roslaunch person_sim spawn_person.launch 
... logging to /home/robot/.ros/log/d4d37442-ff59-11eb-906a-db8f4ebf8eb8/roslaunch-robot-133639.log
Checking log directory for disk usage. This may take a while.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://robot:43401/

SUMMARY
========

PARAMETERS
 * /rosdistro: noetic
 * /rosversion: 1.15.11

NODES
  /
    person_standing_spawn_urdf (gazebo_ros/spawn_model)

ROS_MASTER_URI=http://localhost:11311

process[person_standing_spawn_urdf-1]: started with pid [133668]
[INFO] [1629204731.354375, 0.000000]: Loading model XML from file /home/robot/robot_ws/src/ur5-simulation-package/person_sim/models/model.sdf
[INFO] [1629204731.359082, 43.753000]: Waiting for service /gazebo/spawn_sdf_model
[INFO] [1629204731.364632, 43.759000]: Calling service /gazebo/spawn_sdf_model
[INFO] [1629204731.552085, 43.889000]: Spawn status: SpawnModel: Successfully spawned entity
[person_standing_spawn_urdf-1] process has finished cleanly
log file: /home/robot/.ros/log/d4d37442-ff59-11eb-906a-db8f4ebf8eb8/person_standing_spawn_urdf-1*.log
all processes on machine have died, roslaunch will exit
shutting down processing monitor...
... shutting down processing monitor complete
done

After that I do not see any sdf model was spawned in the Gazebo world and also as can be seen above that it prompts as all processes on the machine have died, roslaunch woll exit. Any help in resolving this issue would be appreciated.

Thank you.

Asked by Anirban Sinha on 2021-08-17 21:56:29 UTC

Answer 1

Hello, instead of creating three separate launch files for each of your models, you might want to create a .world file containing all your models and then use a single .launch to start the simulation Please refer to the "creating a custom world file" part of this tutorial for more information.

Basically, your .world file can be something like this:

<?xml version="1.0" ?>
<sdf version="1.4">
<world name="default">
<include>
<uri>model://person_standing</uri>
  <name>person_standing</name>
  <pose>5 7 0 0 0 0</pose>
</include>  
</world>
</sdf>

Then create a launch file to start the simulation as well as spawn any custom models using the spawn_model method. Something like this:

 <launch>

  <!-- This launch file launches a world as described in the .world file. It then spawns a custom robot model -->


 <!-- Generate the world based on the empty world and change only the below-mentioned arguments -->

 <include file="$(find gazebo_ros)/launch/empty_world.launch">

<arg name="world_name" value="$(find pkg_name)/worlds/custom_world.world"/>
<arg name="paused" value="true"/>
<arg name="use_sim_time" value="true"/>
<arg name="gui" value="true"/>
<arg name="recording" value="false"/>
<arg name="debug" value="false"/>
</include>

<!-- Spawn a custom model into Gazebo -->  
<param name="robot_description" command="cat '$(find pkg_name)/urdf/model_name.urdf'"/>
<node name="spawn_urdf" pkg="gazebo_ros" type="spawn_model" output="screen" args="-urdf -param robot_description -x 0 -y 0 -z 0 -model test_robot"/>

 </launch>

Asked by anishdiwan on 2021-08-20 23:34:56 UTC

Comments

Thank you for your suggestion. I had created a minimal example which I have posted here . I am able to solve the problem based on your suggestion and the other given in the link.

Asked by Anirban Sinha on 2021-08-31 08:12:38 UTC

debugging spawning sdf model in Gazebo

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