Programming Robots with ROS

Chapter 6. Robots and Simulators

The previous chapters discussed many fundamental concepts of ROS. They may have seemed rather vague and abstract, but those concepts were necessary to describe how data moves around in ROS and how its software systems are organized. In this chapter, we will introduce common robot subsystems and describe how the ROS architecture handles them. Then, we will introduce the robots that we will use throughout the remainder of the book and describe the simulators in which we can most easily experiment with them.

Subsystems

Like all complex machines, robots are most easily designed and analyzed by considering one subsystem at a time. In this section, we will introduce the main subsystems commonly found on the types of robots considered in this book. Broadly speaking, they can be divided into three categories: actuation, sensing, and computing. In the ROS context, actuation subsystems are the subsystems that interact directly with how the robot’s wheels or arms move. Sensing subsystems interact directly with sensor hardware, such as cameras or laser scanners. Finally, the computational subsystems are what tie actuators and sensing together, with (ideally) some relatively intelligent processing that allows the robot to perform useful tasks. We will introduce these subsystems in the next few sections. Note that we are not attempting to provide an exhaustive discussion; rather, we are trying to describe these subsystems just deeply enough to convey the issues ...