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

How to control Crazyflie


As you have seen throughout this book, the cmd_vel topic (the geometry_msgs/Twist message) is the common control method for ROS robots, whether driving on the ground or flying in the air. For TurtleBot, mobile_base_commands/velocity and cmd_vel_mux/input/navi are used to move around the base. For Crazyflie, the crazyflie/cmd_vel topic is published to control the flight of the quadrotor.

Within the crazyflie_autonomous package, the crazyflie_controller node (control_crazyflie.py) determines the Crazyflie's control state and publishes the crazyflie/cmd_vel topic. To launch the crazyflie_controller node, the control_crazyflie.launch file is used. This launch file also launches the crazyflie_window node that observes the Crazyflie and takes action when it flies near the edge of the Kinect image frame. The function of this node is described in the subsequent section, using an observer mode.

Crazyflie control states

The crazyflie_controller node has five states of flight...