Book Image

Mastering ROS for Robotics Programming - Second Edition

By : Jonathan Cacace, Lentin Joseph
Book Image

Mastering ROS for Robotics Programming - Second Edition

By: Jonathan Cacace, Lentin Joseph

Overview of this book

In this day and age, robotics has been gaining a lot of traction in various industries where consistency and perfection matter. Automation is achieved via robotic applications and various platforms that support robotics. The Robot Operating System (ROS) is a modular software platform to develop generic robotic applications. This book focuses on the most stable release of ROS (Kinetic Kame), discusses advanced concepts, and effectively teaches you programming using ROS. We begin with aninformative overview of the ROS framework, which will give you a clear idea of how ROS works. During the course of this book, you’ll learn to build models of complex robots, and simulate and interface the robot using the ROS MoveIt! motion planning library and ROS navigation stacks. Learn to leverage several ROS packages to embrace your robot models. After covering robot manipulation and navigation, you’ll get to grips with the interfacing I/O boards, sensors, and actuators of ROS. Vision sensors are a key component of robots, and an entire chapter is dedicated to the vision sensor and image elaboration, its interface in ROS and programming. You’ll also understand the hardware interface and simulation of complex robots to ROS and ROS Industrial. At the end of this book, you’ll discover the best practices to follow when programming using ROS.
Table of Contents (22 chapters)
Title Page
Copyright and Credits
www.PacktPub.com
Contributors
Preface
Index

Understanding ROS nodelets


Nodelets are specific ROS nodes designed to run multiple algorithms within the same process in an efficient way, executing each process as threads. The threaded nodes can communicate with each other efficiently without overloading the network, with zero copy transport between two nodes. These threaded nodes can communicate with external nodes too.

As we did using pluginlib, in nodelets, we can also dynamically load each class as a plugin, which has a separate namespace. Each loaded class can act as separate nodes, which are on a single process called nodelet.

Nodelets are used when the volume of data transferred between nodes are very high; for example, in transferring data from 3D sensors or cameras.

Next, we will look at how to create a nodelet.

Creating a nodelet

In this section, we are going to create a basic nodelet that can subscribe a string topic called /msg_in and publish the same string (std_msgs/String) on the topic /msg_out.

Step 1 - Creating a package for...