ROS 2 Integration#

In this tutorial we will learn how to Integrate ROS 2 with Ignition. We will establish communication between them. This can help in many aspects; we can receive data or commands from ROS and apply it to Ignition and vice versa.

ros_ign_bridge#

ros_ign_bridge provides a network bridge which enables the exchange of messages between ROS 2 and Ignition Transport. Its support is limited to only certain message types. Please, check this README to verify if your message type is supported by the bridge.

Requirements#

For this tutorial to work correctly make sure you have the following installed:

Bidirectional communication#

We can initialize a bidirectional bridge so we can have ROS as the publisher and Ignition as the subscriber or vice versa.

For example:

ros2 run ros_ign_bridge parameter_bridge /TOPIC@ROS_MSG@IGN_MSG

The ros2 run ros_ign_bridge parameter_bridge command simply runs the parameter_bridge code from the ros_ign_bridge package. Then, we specify our topic /TOPIC over which the messages will be sent. The first @ symbol delimits the topic name from the message types. Following the first @ symbol is the ROS message type.

The ROS message type is followed by an @, [, or ] symbol where:

@ is a bidirectional bridge.
[ is a bridge from Ignition to ROS.
] is a bridge from ROS to Ignition.

Have a look at these examples explaining how to make communication connections from ROS to Ignition and vice versa.

Publish key strokes to ROS#

Let’s send messages to ROS using the Key Publisher an Ignition plugin.

Note: Make sure to have all workspaces you need (ROS, Ignition and, ros_ign…) sourced.

First we will start a bridge between ROS and Ignition specifying the topic at which the Key Publisher plugin sends messages and also the type of the messages as follows:

ros2 run ros_ign_bridge parameter_bridge /keyboard/keypress@std_msgs/msg/Int32@ignition.msgs.Int32

We started a bridge on /keyboard/keypress topic with message of type Int32. For ROS it is std_msgs/msg/Int32 and for Ignition it is ignition.msgs.Int32

In another terminal launch an Gazebo Sim world, for example the empty.sdf world:

ign gazebo empty.sdf

Then add the Key Publisher plugin from the dropdown menu on the top right corner.

empty_world_with_KeyPublisher

In another terminal start the ROS listener:

ros2 topic echo /keyboard/keypress

This command listens to the messages sent over the /keyboard/keypress topic.

On the Ignition window, press on the keyboard keys and you should find data on the listener terminal. This is what the terminals should look like:

exchange_messages

Now it’s your turn! Try to send data from ROS to Ignition. You can also try different data types and different directions of communication.

Video walk-through#

A video walk-through of this tutorial is available from our YouTube channel: Ignition tutorials: ROS 2 Foxy integration.