ROS2 Gazebo Project

#gazebo   #garden   #gz   #simulation   #ros2   #launch   #project   #template  

---

Table of Content

ROS2 Gazebo Project

A template project integrating ROS 2 and Gazebo simulator. base on

• <name>_description: holds the sdf description of the simulated system and any other assets.
• <name>_gazebo: holds gazebo specific code and configurations
• <name>_application: holds ros2 specific code and configurations.
• <name>_bringup: holds launch files and high level utilities.

Gazebo Garden ROS2 humble

ros_gz package binaries not compatible with gazebo garden we need to download the package and build it as part of the workspace. check github ros_gz

---

Template

The template base on ament_cmake packages I prepared ament_python package,

Warning

The template project use dsv file to config gazebo environment variables GZ_SIM_RESOURCE_PATH GZ_SIM_SYSTEM_PLUGIN_PATH The ament_python not support the dsv or i don’t find how to use this feature I config the environment variable from the launch files more

Add copy folder function to setup.py

Add helper method to copy data_files files and folders recursive.

def package_files(directory_list):
"""helper method to copy data_files recursive
"""
data_files=[
    ('share/ament_index/resource_index/packages',['resource/' + package_name]),
    ('share/' + package_name, ['package.xml']),
]
paths_dict = {}
for directory in directory_list:
    for (path, _, filenames) in os.walk(directory):
        for filename in filenames:
            file_path = os.path.join(path, filename)
            install_path = os.path.join('share', package_name, path)
            if install_path in paths_dict:
                paths_dict[install_path].append(file_path)
            else:
                paths_dict[install_path] = [file_path]

for src, dst in paths_dict.items():
    data_files.append((src, dst))

return data_files

usage

setup(
name=package_name,
version='0.0.0',
packages=find_packages(exclude=['test']),
data_files=package_files(["models"]),
...
...
)

---

launch

Basic launch run Gazebo world with model from (_description) project

basic.launch.py

import pathlib
from ament_index_python.packages import get_package_share_directory

import launch
from launch.actions import IncludeLaunchDescription, SetEnvironmentVariable
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch.substitutions import EnvironmentVariable


def generate_launch_description():
    ld = launch.LaunchDescription()
    pkg_ros_gz_sim = get_package_share_directory("ros_gz_sim")
    pkg_project_gazebo = get_package_share_directory("nav_gazebo")
    pkg_project_description = get_package_share_directory("nav_description")

    modules = pathlib.Path(pkg_project_description).joinpath("models").as_posix()
    worlds = pathlib.Path(pkg_project_gazebo).joinpath("worlds").as_posix()

    resources = ":".join([modules, worlds])

    gz_resource_path = SetEnvironmentVariable(
        name="GZ_SIM_RESOURCE_PATH",
        value=[EnvironmentVariable("GZ_SIM_RESOURCE_PATH"), resources],
    )

    gz_sim = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            pathlib.Path(pkg_ros_gz_sim)
            .joinpath("launch", "gz_sim.launch.py")
            .as_posix()
        ),
        launch_arguments={
            "gz_args": "-v4 -r empty.sdf"
        }.items(),
    )

    ld.add_action(gz_resource_path)
    ld.add_action(gz_sim)
    return ld