Robot Operating System
For the programming assignments in this class, we will use a software platform called “Robot Operating System,” or ROS. The official description is:
The Robot Operating System (ROS) is a set of software libraries
and tools for building robot applications.
Goal for today: Understand why ROS exists and understand the
basic concepts that ROS uses.
Why ROS exists
Distributed computation
Software for robots is often distributed.- Sending commands from a human's desktop computer to a robot.
- Multiple robots cooperating with each other.
- Multiple computers performing separate but related tasks in a single robot.
- Software decomposed into many smaller, stand-alone parts.
Code reuse
Software development is painful if standard algorithms must be re-implemented for each new robot or operating environment. ROS makes this easier by providing usable implementations of many robotics algorithms, including both reliable, commonly-used techniques, and leading-edge research results. Equally important, because these algorithms interact with each other using the message passing system described above, it is easy to combine many algorithms in a single application.Simulation
Robot programming is often much faster when the part of the initial testing can be done using a simulator, rather than a real robot. ROS makes this easier by providing a consistent way for simulators and robots to expose the same APIs.
The code never “knows” whether it is talking to a real
robot or to a simulator.
Note that ROS is not a simulator. Instead, this slide
is saying that the architecture of ROS works well for swapping
between simulators and real robots, with only minimal changes to
the code.Basic ROS Concepts
Some nouns
- A node is an executing program that uses ROS to communicate with other nodes.
- A topic is a channel for one-way, many-to-many communication between nodes, from publishers to subscribers, based on sending messages.
- The ROS graph has edges for each publish-subscribe relationship.
More nouns
- A service is a channel for two-way, one-to-one communication between a client and a server, based on a request and a response.
- An action is a method for asking a node to complete a time-extended task, based on a request (or goal) which leads to a result, along with feedback along the way.
- An interface is a data type used for a topic, service, or action.
But wait, there's more!
- A package is a collection of related executables and associated files.
- A launch file is a Python program or XML file used to launch and configure several nodes at once.
- A parameter is a bit of configuration data associated with a node.
- A bag is a file that store messages to be replayed later.
Getting more information
ROS versions
Major versions:- ROS1: 2007–2025
- ROS2: 2015–present
- Ardent Apalone
- Bouncy Bolson
- Crystal Clemmys
- Dashing Diademata
- Eloquent Elusor
- Galactic Geochelone
- Foxy Fitzroy
- Humble Hawksbill
- Iron Irwini
- Jazzy Jalisco
- Jazzy Jalisco
- Kilted Kaiju