Book Image

ROS Robotics By Example, Second Edition - Second Edition

By : Carol Fairchild, Lentin Joseph, Dr. Thomas L. Harman
Book Image

ROS Robotics By Example, Second Edition - Second Edition

By: Carol Fairchild, Lentin Joseph, Dr. Thomas L. Harman

Overview of this book

ROS is a robust robotics framework that works regardless of hardware architecture or hardware origin. It standardizes most layers of robotics functionality from device drivers to process control and message passing to software package management. But apart from just plain functionality, ROS is a great platform to learn about robotics itself and to simulate, as well as actually build, your first robots. This does not mean that ROS is a platform for students and other beginners; on the contrary, ROS is used all over the robotics industry to implement flying, walking and diving robots, yet implementation is always straightforward, and never dependent on the hardware itself. ROS Robotics has been the standard introduction to ROS for potential professionals and hobbyists alike since the original edition came out; the second edition adds a gradual introduction to all the goodness available with the Kinetic Kame release. By providing you with step-by-step examples including manipulator arms and flying robots, the authors introduce you to the new features. The book is intensely practical, with space given to theory only when absolutely necessary. By the end of this book, you will have hands-on experience on controlling robots with the best possible framework.
Table of Contents (18 chapters)
ROS Robotics By Example Second Edition
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

Baxter's arms and forward kinematics


Considering Baxter's arms up to the wrist cuff, each arm has seven values that define the rotation angle of each joint. Since the link lengths and joint angles are known, it is possible to calculate the position and orientation of the gripper attached to the wrist. This approach to calculating the pose of the gripper, given the configuration of the arm is called forward kinematic analysis.

Fortunately, ROS has programs that allow the calculation and publishing of the joint angles, given a particular position and orientation of the gripper. The particular topic for Baxter is /robot/joint_states.

Joints and joint state publisher

Baxter has seven joints in each of its two arms and two more joints in its head. The /robot/joint_states topic publishes the current joint states of the head pan (side-to-side) joint and the 14 arm joints. These joint states show position, velocity, and effort values for each of these joints. Joint position values are in radians, velocity...