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19-ROS 2 Gazebo Simulation Platform

1. Introduction to Gazebo​

Gazebo is the most commonly used 3D physics simulation platform in the ROS system. It supports a dynamics engine and enables high-quality graphics rendering. It not only simulates the robot and its surrounding environment, but also incorporates physical properties such as friction and elasticity.

For example, if we want to develop a Mars rover, we can simulate the Martian surface environment in Gazebo. Or, if we're developing a drone, battery life and flight restrictions prevent us from frequently experimenting with the actual drone. In these cases, we can use Gazebo to simulate first, then deploy to the actual drone once the algorithm is fully developed.

Simulation platforms like Gazebo can help us verify robotic algorithms, optimize robot designs, and test robot applications, providing more possibilities for robotics development.

note

This section is for learning purposes only. The tutorial does not configure the environment because real-device debugging is used.

2. Installation and Operation​

Install Gazebo​

sudo apt install ros-${ROS_DISTRO}-gazebo-*

Run Gazebo​

Launch Gazebo using the command below or directly from the desktop icon:

gazebo --verbose -s libgazebo_ros_init.so -s libgazebo_ros_factory.so

Gazebo Startup Gazebo Interface Gazebo World

Optional: Offline Model Download​

To ensure smooth model loading, you can download offline models and place them in:

~/.gazebo/models

External source: https://github.com/osrf/gazebo_models

3. Start the Gazebo Node and Service​

View Nodes​

ros2 node list

Expected output:

/gazebo

Node List

View Services​

ros2 service list

Service List

Key services:

  • /spawn_entity --- Load models into Gazebo\
  • /get_model_list --- Get model list\
  • /delete_entity --- Delete models

4. Create a Function Package​

Create a package for storing URDF and launch files:

ros2 pkg create myrobot --build-type ament_cmake

Create folders and files:

  • launch/
  • urdf/demo01_base.urdf

demo01_base.urdf​

<robot name="myrobot">
  <link name="base_link">
    <visual>
      <geometry>
        <box size="0.2 0.2 0.2"/>
      </geometry>
      <origin xyz="0.0 0.0 0.0"/>
    </visual>
    <collision>
      <geometry>
        <box size="0.2 0.2 0.2"/>
      </geometry>
      <origin xyz="0.0 0.0 0.0"/>
    </collision>
    <inertial>
      <mass value="0.1"/>
      <inertia ixx="0.000190416666667" ixy="0" ixz="0" iyy="0.0001904" iyz="0" izz="0.00036"/>
    </inertial>
  </link>
  <gazebo reference="base_link">
    <material>Gazebo/Red</material>
  </gazebo>
</robot>

5. Writing the Launch File​

The launch file handles:

  1. Starting Gazebo\
  2. Spawning the robot model

Start Gazebo Command​

start_gazebo_cmd = ExecuteProcess(
    cmd=['gazebo', '--verbose',
         '-s', 'libgazebo_ros_init.so',
         '-s', 'libgazebo_ros_factory.so'],
    output='screen')

Spawn Model Command​

spawn_entity_cmd = Node(
    package='gazebo_ros',
    executable='spawn_entity.py',
    arguments=['-entity', robot_name_in_model, '-file', urdf_model_path],
    output='screen')
  • -entity: Model name\
  • -file: URDF file path

6. Complete Launch File Example​

Create bringup_model.launch.py inside the launch directory:

import os
from launch import LaunchDescription
from launch.actions import ExecuteProcess
from launch_ros.actions import Node
from launch_ros.substitutions import FindPackageShare

def generate_launch_description():

    pkg_share = FindPackageShare(package='myrobot').find('myrobot')
    urdf_model_path = os.path.join(pkg_share, 'urdf/demo01_base.urdf')

    start_gazebo_cmd = ExecuteProcess(
        cmd=['gazebo', '--verbose',
             '-s', 'libgazebo_ros_init.so',
             '-s', 'libgazebo_ros_factory.so'],
        output='screen')

    spawn_entity_cmd = Node(
        package='gazebo_ros',
        executable='spawn_entity.py',
        arguments=['-entity', 'myrobot',
                   '-file', urdf_model_path],
        output='screen')

    return LaunchDescription([
        start_gazebo_cmd,
        spawn_entity_cmd
    ])

This documentation is maintained by HemiHex for ROS 2 Gazebo simulation workflows.