ros_gz_sim

Tools for using Gazebo Sim simulation with ROS.

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README

ROS + Gazebo Sim

This package contains things that make it convenient to integrate ROS with Gazebo, such as:

• Launch files

• ROS-enabled executables

Run Gazebo Sim

There’s a convenient launch file, try for example:

ros2 launch ros_gz_sim gz_sim.launch.py gz_args:="shapes.sdf"

Spawn entities

The create executable can be used to spawn SDF or URDF entities from:

• A file on disk or from Gazebo Fuel

• A ROS parameter

For example, start Gazebo Sim:

ros2 launch ros_gz_sim gz_sim.launch.py

then spawn a model:

ros2 run ros_gz_sim create -world default -file 'https://fuel.ignitionrobotics.org/1.0/openrobotics/models/Gazebo'

See more options with:

ros2 run ros_gz_sim create --helpshort

Using <gazebo_ros> to export model paths in package.xml

The <gazebo_ros> tag inside the <export> tag of a package.xml file can be used to add paths to GZ_SIM_RESOURCE_PATH and GZ_SIM_SYSTEM_PLUGIN_PATH, which are environment variables used to configure Gazebo search paths for resources (e.g. SDFormat files, meshes, etc) and plugins respectively.

The values in the attributes gazebo_model_path and gazebo_media_path are appended to GZ_SIM_RESOURCE_PATH. The value of plugin_path is appended to GZ_SIM_SYSTEM_PLUGIN_PATH. See the Finding resources tutorial to learn more about these environment variables.

The keyword ${prefix} can be used when setting these values and it will be expanded to the package’s share path (i.e., the value of ros2 pkg prefix --share <package name>)

<export>
   <gazebo_ros gazebo_model_path="${prefix}/models"/>
   <gazebo_ros gazebo_media_path="${prefix}/media"/>
   <gazebo_ros plugin_path="${prefix}/plugins"/>
</export>

Thus the required directory needs to be installed from CMakeLists.txt

install(DIRECTORY models
    DESTINATION share/${PROJECT_NAME})

In order to reference the models in a ROS package unambiguously, it is recommended to set the value of gazebo_model_path to be the parent of the prefix.

<export>
   <gazebo_ros gazebo_model_path="${prefix}/../"/>
</export>

Consider an example where we have a ROS package called my_awesome_pkg and it contains an SDFormat model cool cool_robot:

my_awesome_pkg
├── models
│   └── cool_robot
│       ├── model.config
│       └── model.sdf
└── package.xml

With gazebo_model_path="${prefix}/../ set up, we can reference the cool_robot model in a world file using the package name in the uri:

<sdf version="1.6">
  <world name="default">
    <include>
      <uri>package://my_awesome_pkg/models/cool_robot</uri>
    </include>
  </world>
</sdf>

However, if we set gazebo_model_path=${prefix}/models, we would need to reference cool_robot as package://cool_robot, which might have a name conflict with other models in the system.