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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 transforms

The navigation stack needs to know the position of the sensors, wheels, and joints.

To do that, we use the Transform Frames (tf) software library. It manages a transform tree. You could do this with mathematics, but if you have a lot of frames to calculate, it will be a bit complicated and messy.

Thanks to tf, we can add more sensors and parts to the robot, and tf will handle all the relations for us.

If we put the laser 10 cm backwards and 20 cm above with reference to the origin of the base_link coordinates, we would need to add a new frame to the transformation tree with these offsets.

Once inserted and created, we could easily know the position of the laser with reference to the base_link value or the wheels. The only thing we need to do is call the tf library and get the transformation.

Creating a broadcaster

Let's test this with a simple code. Create a new file in chapter5_tutorials/src with the name tf_broadcaster.cpp, and put the following code inside it:

#include...
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