README

ROS + Gazebo Sim demos

This package contains demos showing how to use Gazebo Sim with ROS.

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"

Air pressure

Publishes fluid pressure readings.

ros2 launch ros_gz_sim_demos air_pressure.launch.xml

This demo also shows the use of custom QoS parameters. The sensor data is published as as “best-effort”, so trying to subscribe to “reliable” data won’t work. See the difference between:

ros2 topic echo /air_pressure --qos-reliability best_effort

And

ros2 topic echo /air_pressure --qos-reliability reliable

Battery

Get the current state of a battery.

ros2 launch ros_gz_sim_demos battery.launch.py

Then send a command so the vehicle moves and drains the battery.

ros2 topic pub /model/vehicle_blue/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 5.0}, angular: {z: 0.5}}"

Camera

Publishes RGB camera image and info.

Images can be exposed to ROS through ros_gz_bridge or ros_gz_image.

Using the image bridge (unidirectional, uses image_transport):

ros2 launch ros_gz_sim_demos image_bridge.launch.py

Using the regular bridge:

ros2 launch ros_gz_sim_demos camera.launch.xml

To use a camera that only publishes information when triggered:

ros2 launch ros_gz_sim_demos triggered_camera.launch.xml

Trigger the camera:

ros2 topic pub /camera/trigger std_msgs/msg/Bool "{data: true}" --once

Diff drive

Send commands to a differential drive vehicle and listen to its odometry.

ros2 launch ros_gz_sim_demos diff_drive.launch.xml

Then send a command

ros2 topic pub /model/vehicle_blue/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 5.0}, angular: {z: 0.5}}"

This demo also shows the use of custom QoS parameters. The commands are subscribed to as “reliable”, so trying to publish “best-effort” commands won’t work. See the difference between:

ros2 topic pub /model/vehicle_blue/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 5.0}, angular: {z: 0.0}}" --qos-reliability reliable

And

ros2 topic pub /model/vehicle_blue/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 5.0}, angular: {z: 0.0}}" --qos-reliability best_effort

Depth camera

Depth camera data can be obtained as:

  • sensor_msgs/msg/Image, through ros_gz_bridge or ros_gz_image

  • sensor_msgs/msg/PointCloud2, through ros_gz_point_cloud

Using the image bridge (unidirectional, uses image_transport):

ros2 launch ros_gz_sim_demos image_bridge.launch.py image_topic:=/depth_camera

TODO: Blocked by ros_gz_point_cloud issue.

Using Gazebo Sim plugin:

ros2 launch ros_gz_sim_demos depth_camera.launch.py

GPU lidar

GPU lidar data can be obtained as:

  • sensor_msgs/msg/LaserScan, through the ros_gz_bridge

  • sensor_msgs/msg/PointCloud2, through the ros_gz_bridge or ros_gz_point_cloud

Using the bridge:

ros2 launch ros_gz_sim_demos gpu_lidar_bridge.launch.xml

TODO: Blocked by ros_gz_point_cloud issue.

Using Gazebo Sim plugin:

ros2 launch ros_gz_sim_demos gpu_lidar.launch.py

IMU

Publishes IMU readings.

ros2 launch ros_gz_sim_demos imu.launch.xml

TODO: IMU display missing for RViz2

Magnetometer

Publishes magnetic field readings.

ros2 launch ros_gz_sim_demos magnetometer.launch.xml

GNSS

Publishes satellite navigation readings, only available in Fortress on.

GNSS information can be obtained as:

# sensor_msgs/msg/NavSatFix
ros2 launch ros_gz_sim_demos navsat.launch.xml
# gps_msgs/msg/GPSFix
ros2 launch ros_gz_sim_demos navsat_gpsfix.launch.xml

RGBD camera

RGBD camera data can be obtained as:

  • sensor_msgs/msg/Image, through ros_gz_bridge or ros_gz_image

  • sensor_msgs/msg/PointCloud2, through ros_gz_bridge or ros_gz_point_cloud

Using the image bridge (unidirectional, uses image_transport):

# RGB image
ros2 launch ros_gz_sim_demos image_bridge.launch.py image_topic:=/rgbd_camera/image
# Depth image
ros2 launch ros_gz_sim_demos image_bridge.launch.py image_topic:=/rgbd_camera/depth_image

Using the regular bridge:

ros2 launch ros_gz_sim_demos rgbd_camera_bridge.launch.xml

TODO: Blocked by ros_gz_point_cloud issue.

Using Gazebo Sim plugin:

ros2 launch ros_gz_sim_demos rgbd_camera.launch.py

Robot description publisher

Leverage the robot description publisher to spawn a new urdf model in gazebo and show it in rviz2. To try the demo launch:

ros2 launch ros_gz_sim_demos robot_description_publisher.launch.py

Joint States Publisher

Publishes joint states of the robot.

To try the demo launch:

ros2 launch ros_gz_sim_demos joint_states.launch.py

Bridging joint state and pose publishers

The launch file demonstrates bridging Gazebo poses to TFMessage to visualize the pose and transforms of a robot in rviz.

To try the demo launch:

ros2 launch ros_gz_sim_demos tf_bridge.launch.xml

Managing Entities

The ros_gz_sim package provides a set of utilities for managing entities (models, lights, links, etc.) in Gazebo simulations through ROS 2. This package enables seamless communication between ROS 2 and Gazebo, allowing you to:

  • Spawn entities: Add new models and objects to a running Gazebo simulation

  • Set entity poses: Dynamically adjust the position and orientation of existing entities

  • Delete entities: Remove entities from the simulation environment

Launching Gazebo

gz sim -v 4 ~/ros2_ws/src/ros_gz/ros_gz_sim_demos/worlds/default.sdf

1. Spawning Entities

Spawn new entities into the simulation:

  1. Run the ROS-Gazebo bridge for the spawn service:

ros2 run ros_gz_bridge parameter_bridge /world/default/create@ros_gz_interfaces/srv/SpawnEntity

  1. Spawn your entity:

ros2 run ros_gz_sim spawn_entity --name <model_name> --sdf_filename <path_to_sdf_file> [--pos x y z] [--quat x y z w | --euler roll pitch yaw]

Example:

ros2 run ros_gz_sim spawn_entity --name cardboard_box --sdf_filename $(ros2 pkg prefix ros_gz_sim_demos)/share/ros_gz_sim_demos/models/cardboard_box/model.sdf --pos 1.0 2.0 0.5 --euler 0.0 0.0 1.57

or

ros2 run ros_gz_sim spawn_entity --name cardboard_box --sdf_filename /full/path/to/ros_gz_ws/src/ros_gz_sim_demos/models/cardboard_box/model.sdf --pos 1.0 2.0 0.5 --euler 0.0 0.0 1.57

spawn_entity

2. Setting Entity Poses

Dynamically adjust the position and orientation of existing entities:

  1. Run the ROS-Gazebo bridge for the set pose service:

ros2 run ros_gz_bridge parameter_bridge /world/default/set_pose@ros_gz_interfaces/srv/SetEntityPose

  1. Set the entity’s pose:

ros2 run ros_gz_sim set_entity_pose [--name NAME | --id ID] [--type TYPE] [--pos X Y Z] [--quat X Y Z W | --euler ROLL PITCH YAW]

Examples:

Using entity name with Euler angles for rotation:

ros2 run ros_gz_sim set_entity_pose --name cardboard_box --pos 3.0 4.0 1.0 --euler 0.0 0.0 1.57

Using entity ID with quaternion for rotation:

ros2 run ros_gz_sim set_entity_pose --id 8 --pos 3.0 4.0 1.0 --quat 0.0 0.0 0.7071 0.7071

set_entity

3. Deleting Entities

Remove entities from the simulation:

  1. Run the ROS-Gazebo bridge for the delete service:

ros2 run ros_gz_bridge parameter_bridge /world/default/remove@ros_gz_interfaces/srv/DeleteEntity

  1. Delete the entity:

ros2 run ros_gz_sim delete_entity [--name NAME | --id ID] [--type TYPE]

Examples:

Using entity name:

ros2 run ros_gz_sim delete_entity --name cardboard_box

Using entity ID:

ros2 run ros_gz_sim delete_entity --id 8

Using a specific entity type:

ros2 run ros_gz_sim delete_entity --name cardboard_box --type 2

delete_entity

Entity Type Reference

When using the set_entity_pose and delete_entity commands, you can specify the entity type using the --type flag. The following type values are available:

Value

Entity Type

0

NONE

1

LIGHT

2

LINK

3

VISUAL

4

COLLISION

5

SENSOR

6

MODEL (default)