Bridge communication between ROS and Gazebo

This package provides a network bridge which enables the exchange of messages between ROS and Gazebo Transport.

The following message types can be bridged for topics:

And the following for services:

Run ros2 run ros_gz_bridge parameter_bridge -h for instructions.

Example 1a: Gazebo Transport talker and ROS 2 listener

Start the parameter bridge which will watch the specified topics.

# Shell A:
. ~/bridge_ws/install/setup.bash
ros2 run ros_gz_bridge parameter_bridge /chatter@std_msgs/msg/String@ignition.msgs.StringMsg

Now we start the ROS listener.

# Shell B:
. /opt/ros/galactic/setup.bash
ros2 topic echo /chatter

Now we start the Gazebo Transport talker.

# Shell C:
ign topic -t /chatter -m ignition.msgs.StringMsg -p 'data:"Hello"'

Example 1b: ROS 2 talker and Gazebo Transport listener

Start the parameter bridge which will watch the specified topics.

# Shell A:
. ~/bridge_ws/install/setup.bash
ros2 run ros_gz_bridge parameter_bridge /chatter@std_msgs/msg/String@ignition.msgs.StringMsg

Now we start the Gazebo Transport listener.

# Shell B:
ign topic -e -t /chatter

Now we start the ROS talker.

# Shell C:
. /opt/ros/galactic/setup.bash
ros2 topic pub /chatter std_msgs/msg/String "data: 'Hi'" --once

Example 2: Run the bridge and exchange images

In this example, we're going to generate Gazebo Transport images using Gazebo Sim, that will be converted into ROS images, and visualized with rqt_image_viewer.

First we start Gazebo Sim (don't forget to hit play, or Gazebo Sim won't generate any images).

# Shell A:
ign gazebo sensors_demo.sdf

Let's see the topic where camera images are published.

# Shell B:
ign topic -l | grep image
/rgbd_camera/depth_image
/rgbd_camera/image

Then we start the parameter bridge with the previous topic.

# Shell B:
. ~/bridge_ws/install/setup.bash
ros2 run ros_gz_bridge parameter_bridge /rgbd_camera/image@sensor_msgs/msg/Image@ignition.msgs.Image

Now we start the ROS GUI:

# Shell C:
. /opt/ros/galactic/setup.bash
ros2 run rqt_image_view rqt_image_view /rgbd_camera/image

You should see the current images in rqt_image_view which are coming from Gazebo (published as Gazebo Msgs over Gazebo Transport).

The screenshot shows all the shell windows and their expected content (it was taken using ROS 2 Galactic and Gazebo Fortress):

Example 3: Static bridge

In this example, we're going to run an executable that starts a bidirectional bridge for a specific topic and message type. We'll use the static_bridge executable that is installed with the bridge.

The example's code can be found under ros_gz_bridge/src/static_bridge.cpp. In the code, it's possible to see how the bridge is hardcoded to bridge string messages published on the /chatter topic.

Let's give it a try, starting with Gazebo -> ROS 2.

On terminal A, start the bridge:

ros2 run ros_gz_bridge static_bridge

On terminal B, we start a ROS 2 listener:

ros2 topic echo /chatter std_msgs/msg/String

And terminal C, publish an Gazebo message:

ign topic -t /chatter -m ignition.msgs.StringMsg -p 'data:"Hello"'

At this point, you should see the ROS 2 listener echoing the message.

Now let's try the other way around, ROS 2 -> Gazebo.

On terminal D, start an Igntion listener:

ign topic -e -t /chatter

And on terminal E, publish a ROS 2 message:

ros2 topic pub /chatter std_msgs/msg/String 'data: "Hello"' -1

You should see the Gazebo listener echoing the message.

Example 4: Service bridge

It's possible to make ROS service requests into Gazebo. Let's try unpausing the simulation.

On terminal A, start the service bridge:

ros2 run ros_gz_bridge parameter_bridge /world/shapes/control@ros_gz_interfaces/srv/ControlWorld

On terminal B, start Gazebo, it will be paused by default:

ign gazebo shapes.sdf

On terminal C, make a ROS request to unpause simulation:

ros2 service call /world/<world_name>/control ros_gz_interfaces/srv/ControlWorld "{world_control: {pause: false}}"

Example 5: Configuring the Bridge via YAML

When configuring many topics, it is easier to use a file-based configuration in a markup language. In this case, the ros_gz bridge supports using a YAML file to configure the various parameters.

The configuration file must be a YAML array of maps. An example configuration for 5 bridges is below, showing the various ways that a bridge may be specified:

 # Set just topic name, applies to both
- topic_name: "chatter"
  ros_type_name: "std_msgs/msg/String"
  ign_type_name: "ignition.msgs.StringMsg"

# Set just ROS topic name, applies to both
- ros_topic_name: "chatter_ros"
  ros_type_name: "std_msgs/msg/String"
  ign_type_name: "ignition.msgs.StringMsg"

# Set just IGN topic name, applies to both
- ign_topic_name: "chatter_ign"
  ros_type_name: "std_msgs/msg/String"
  ign_type_name: "ignition.msgs.StringMsg"

# Set each topic name explicitly
- ros_topic_name: "chatter_both_ros"
  ign_topic_name: "chatter_both_ign"
  ros_type_name: "std_msgs/msg/String"
  ign_type_name: "ignition.msgs.StringMsg"

# Full set of configurations
- ros_topic_name: "ros_chatter"
  ign_topic_name: "ign_chatter"
  ros_type_name: "std_msgs/msg/String"
  ign_type_name: "ignition.msgs.StringMsg"
  subscriber_queue: 5       # Default 10
  publisher_queue: 6        # Default 10
  lazy: true                # Default "false"
  direction: BIDIRECTIONAL  # Default "BIDIRECTIONAL" - Bridge both directions
                            # "IGN_TO_ROS" - Bridge Ignition topic to ROS
                            # "ROS_TO_IGN" - Bridge ROS topic to Ignition

To run the bridge node with the above configuration:

ros2 run ros_gz_bridge bridge_node --ros-args -p config_file:=$WORKSPACE/ros_gz/ros_gz_bridge/test/config/full.yaml

API

ROS 2 Parameters:

• subscription_heartbeat - Period at which the node checks for new subscribers for lazy bridges.
• config_file - YAML file to be loaded as the bridge configuration

Changelog for package ros_gz_bridge

0.244.6 (2022-09-14)

0.244.5 (2022-09-12)

• Fix missing msgs include and packages.xml deps (#292)
  • Fix missing msgs include and packages.xml deps
  • Add additional conditions to support gz sim invocation
  • Fix cpplint
• Add missing GZ_VERSION ticktocks (#289)
• Support ros_ign migration (#282) Clean up shared libraries, and tick-tock RosGzPointCloud Tick-tock launch args Hard-tock ign_ in sources Migrate ign, ign_, IGN_ for sources, launch, and test files Migrate IGN_XXX_VER, IGN_T, header guards Migrate launchfile, launchfile args, and test source references Migrate ros_ign_XXX and gz_gazebo -> gz_sim Migrate ros_ign_XXX project names Migrate Ign, ign-, IGN_DEPS, ign-gazebo Migrate ignitionrobotics, ignitionrobotics/ros_ign, osrf/ros_ign Migrate ignition-version, IGNITION_VERSION, Ignition <LIB>, ros_ign_ci
• Move packages and files to gz (#282)
• Contributors: methylDragon

0.244.3 (2022-05-19)

• Feature: set QoS options to override durability (#250) Co-authored-by: Louise Poubel <louise@openrobotics.org>
• [ros2] README updates (service bridge, Gazebo rename) (#252)
• Fix linter tests (#251) Co-authored-by: Louise Poubel <louise@openrobotics.org>
• Adds pose and twist with covariance messages bridging (#222)
  • Added pose, twist and odometry with covariance messages bridging
• Contributors: Aditya Pande, Daisuke Nishimatsu, Louise Poubel

0.244.2 (2022-04-25)

• Support bridging services (#211)
• Added reminder to hit play to receive images. (#237)
• Updated ign topic commnds on README (#221)
• Add conversions for ros_gz_interfaces/WorldControl and builtin_interfaces/Time (#216)
• [ros_gz_interfaces] Add GuiCamera, StringVec, TrackVisual, VideoRecord (#214)
• Break apart ros_subscriber test translation unit (#212)
• Bring ros2 branch up-to-date with Rolling (#213)
• Add missing dependency on rclcpp (#209)
• Separate galactic branch from ros2 branch (#201)