Book Image

ROS Robotics By Example

Book Image

ROS Robotics By Example

Overview of this book

The visionaries who created ROS developed a framework for robotics centered on the commonality of robotic systems and exploited this commonality in ROS to expedite the development of future robotic systems. From the fundamental concepts to advanced practical experience, this book will provide you with an incremental knowledge of the ROS framework, the backbone of the robotics evolution. ROS standardizes many layers of robotics functionality from low-level device drivers to process control to message passing to software package management. This book provides step-by-step examples of mobile, armed, and flying robots, describing the ROS implementation as the basic model for other robots of these types. By controlling these robots, whether in simulation or in reality, you will use ROS to drive, move, and fly robots using ROS control.
Table of Contents (17 chapters)
ROS Robotics By Example
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Index

Introducing rqt tools


The rqt tools (ROS Qt GUI toolkit) that are part of ROS allow graphical representations of ROS nodes, topics, messages, and other information. The ROS wiki lists many of the possible tools that are added to the rqt screen as plugins: http://wiki.ros.org/rqt/Plugins.

The ROS tutorial on topics also describes some of the features of the rqt tools at: http://wiki.ros.org/ROS/Tutorials/UnderstandingTopics

rqt_graph

One of the common uses of rqt is to view the nodes and topics that are active. Bring the TurtleBot up with minimal launch as previously described. Then, on the remote computer, issue the following command:

$ rqt_graph

Select the top-left box, Nodes/Topics (all). The following screenshot of rqt_graph shows the nodes that are active and the connections between the publishers and subscribers that deal with moving the base of the TurtleBot. Pass the cursor over the various items to see the nodes and topics and see how they communicate:

rqt_graph after minimal launch...