Robot Operating System for the DronebotWorkshop Builders. Part 0

What is Robot Operating System (ROS)? It is a system for making it easier to reuse work you or others have already done when programming your robot. In the next couple of sections we will compare and contrast Robot Operating System with the more commonly understood Computer Operating System.

What ROS Is

At its core, ROS encourages and provides five things:

1. Conventions – Many people have written software for Robots. Over time, best practices and conventions have evolved to solve different types of common problems.

2. Modular Design - One of these best practices split the design and implementation of your software into modules. These modules can though about independently of the rest of the system. ROS calls these modules NODES.

3. Messaging System – A modular design requires a system for communicating between the various modules. A large part of understanding ROS is understanding the messaging system

4. Common Tools – Over time, a collection of tools has evolved to enable developers to design, test, and debug their robots. Many of these are visualization tool which enable you to ‘see’ how some part of your robot is working instead of trying to watch a list of numbers go scrolling by.

5. Implementations of common algorithms and services. Many modules have been written to do various common tasks. These modules ranges from ‘drivers’ which enable you to plug your favorite sensor into ROS to complex to do Localization and navigation for you.

6. Community – There is pretty activity community around ROS which writes new code and helps each other through various web forums.

What ROS is NOT:

When learning ROS, it is as important to understand what it is not so you can manage your expectations:

1. Polished System - ROS is not a completely unified system with a polished GUI like we have grown to expect from Computer Operating Systems such as Linux, Mac OS, or Windows. Much of the current development is happening at the ‘tool’ level rather than the UI Level

2. Plug and Play – You can not just boot up ROS on your robot and be off and running. Instead, you have to build you system match you hardware and meet your particular needs.

3. A Computer OS – ROS is not a computer Operating System. It is an additional layer installed on top of of an existing OS. It is most common to run ROS on top of Ubuntu or Raspian.

4. Stable – The technology around robotics is changing rapidly. As the underlying technology changes, ROS, the glue layer, must change as well.

To Use or Not To Use

To be honest, I don’t know. The series is not in any way meant to convince you to use ROS. There are some situations where it is beneficial and other situation where it is not.

1. ROS can be difficult to set up and learn. When you are first learning the electronics, mechanics, and programming to create a robot ROS is just another thing a ToDo list.

2. ROS can add complexity to an already complex subject. When you are just learning to do something simple like turning both wheels 360 degrees in order to go forward it is easier to just program things yourself. On large robots some manufactures make the valid point that the abstraction layers make the end product more brittle.

3. ROS can be a wormhole into another fascinating aspect of Robotics. You can waste a lot of time on the ROS Wiki.

Hopefully though this series and an attempt to build a ROSified version of DB1 in parallel with Bills DB1 you will be ready to make the decision whether or not to use ROS or not on your next project.