How do you use ROS for robot networking?

2 Nodes and topics

Nodes are the basic units of a ROS application that perform specific tasks, such as sensing, planning, or actuating. Nodes communicate with each other by publishing and subscribing to topics, which are named channels that carry messages of a certain type. For example, a node that controls a camera can publish images to a topic called /camera/image, and a node that performs object detection can subscribe to that topic and process the images. To create nodes and topics, you need to use one of the supported programming languages, such as Python or C++, and use the ROS API to define the node behavior and the message structure.

3 Launch files

Launch files are XML files that specify how to launch multiple nodes and set their parameters. Launch files are useful for robot networking, as they allow you to start and stop nodes on different robots and computers with a single command. For example, you can create a launch file that runs a node that controls a robot arm on one robot, a node that controls a robot gripper on another robot, and a node that coordinates their actions on the computer. To create a launch file, you need to use the <launch> tag to enclose the node definitions, and use the <node> tag to specify the node name, package, type, and machine.

4 Rostopic and rosservice

Rostopic and rosservice are command-line tools that let you interact with topics and services on a ROS network. Topics are used for one-way or asynchronous communication, while services are used for two-way or synchronous communication. For example, you can use rostopic to list the active topics, to get information about a topic, or to publish or echo messages on a topic. You can use rosservice to list the available services, to get information about a service, or to call a service and get a response. These tools are helpful for debugging and testing your robot network.

5 Rosbag and rqt

Rosbag and rqt are graphical tools that let you record and visualize data on a ROS network. Rosbag is a tool that allows you to record and play back messages from topics. You can use rosbag to save data from sensors, to analyze data offline, or to replay data for simulation. Rqt is a tool that provides a variety of plugins for visualizing and interacting with nodes, topics, services, parameters, and messages. You can use rqt to monitor the network status, to plot data, to view images, to control parameters, and to create custom interfaces.

6 Rosbridge and roslibjs

Rosbridge and roslibjs are libraries that enable you to use ROS for robot networking with web applications. Rosbridge is a library that provides a WebSocket interface to the ROS network, allowing you to communicate with nodes using JSON messages. Roslibjs is a library that provides a JavaScript API to the ROS network, allowing you to create and run nodes, topics, services, and parameters in a web browser. You can use rosbridge and roslibjs to create web-based interfaces for controlling and monitoring your robots, or to integrate your robots with other web services and platforms.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?