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Effective Robotics Programming with ROS

You're reading from   Effective Robotics Programming with ROS Find out everything you need to know to build powerful robots with the most up-to-date ROS

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Product type Paperback
Published in Dec 2016
Publisher Packt
ISBN-13 9781786463654
Length 468 pages
Edition 3rd Edition
Tools
Concepts
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Authors (3):
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Luis S√°nchez Luis S√°nchez
Author Profile Icon Luis S√°nchez
Luis S√°nchez
Enrique Fernandez Perdomo Enrique Fernandez Perdomo
Author Profile Icon Enrique Fernandez Perdomo
Enrique Fernandez Perdomo
Anil Mahtani Anil Mahtani
Author Profile Icon Anil Mahtani
Anil Mahtani
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Toc

Table of Contents (12) Chapters Close

Preface 1. Getting Started with ROS FREE CHAPTER 2. ROS Architecture and Concepts 3. Visualization and Debugging Tools 4. 3D Modeling and Simulation 5. The Navigation Stack – Robot Setups 6. The Navigation Stack – Beyond Setups 7. Manipulation with MoveIt! 8. Using Sensors and Actuators with ROS 9. Computer Vision 10. Point Clouds Index

Creating a base controller


A base controller is an important element in the navigation stack because it is the only way to effectively control your robot. It communicates directly with the electronics of your robot.

ROS does not provide a standard base controller, so you must write a base controller for your mobile platform.

Your robot has to be controlled with the message type geometry_msgs/Twist. This message was used on the Odometry message that we saw before.

So, your base controller must subscribe to a topic with the name cmd_vel, and must generate the correct commands to move the platform with the correct linear and angular velocities.

We are now going to recall the structure of this message. Type the following command in a shell to see the structure:

$ rosmsg show geometry_msgs/Twist

The output of this command is as follows:

The vector with the name linear indicates the linear velocity for the axes x, y, and z. The vector with the name angular is for the angular velocity on the axes.

For...

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