1. Robot Operating System (ROS): An Introduction
Paul Nyholm
David Wheeler
BYU MAGICC Lab
Brigham Young University

2. Exploration Path Planner
Motivation
Robot 1: Mission Statement
Using an altimeter, Xbox Kinect, and IMU, safely drive through a room creating a map of the environment.
Kinect
Map
Exploration Path Planner
Altimeter
Estimator
IMU
Robot Control

3. Motivation Robot 2: Mission Statement
Using an laser range finder, GPS, and IMU, safely fly to specific user defined waypoints and search for moving vehicles.
Vehicle Detection
Laser
Global Map
Waypoint GUI
GPS
Estimator
IMU
Robot Control

4. Motivation
ROS:
High Modularity
Follows Intuitive Information Flow

5. Exploration Path Planner
Concept
ROS Node
ROS Message
Independent Python or C++ programs.
Node crash protection.
Inter-program communication.
Subscriber
Publisher
Kinect
Map
Exploration Path Planner
Altimeter
Estimator
IMU
/topic_name
Robot Control

6. Concept Subscriber Example: #include "ros/ros.h"
#include "std_msgs/String.h“
void chatterCallback(const std_msgs::String::ConstPtr& msg) {
ROS_INFO("I heard: [%s]", msg->data.c_str()); }
int main(int argc, char **argv)
ros::init(argc, argv, "listener");
ros::NodeHandle n;
ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback);
ros::spin(); return 0;

7. Concept Publisher Example: #include "ros/ros.h"
#include "std_msgs/String.h"
#include <sstream>
int main(int argc, char **argv) {
ros::init(argc, argv, "talker");
ros::NodeHandle n;.
ros::Publisher chatter_pub = n.advertise<std_msgs::String>("chatter", 1000);
ros::Rate loop_rate(10);
int count = 0;
while (ros::ok())
std_msgs::String msg;
std::stringstream ss;
ss << "hello world " << count;
msg.data = ss.str();
ROS_INFO("%s", msg.data.c_str());
chatter_pub.publish(msg);
ros::spinOnce();
loop_rate.sleep();
++count; }
return 0;

8. Concept roscore my_talker
rosrun talker my_talker chatter:=new_chatter_topic
altimeter
roslaunch
rosrun altimeter my_altimeter range:=range_topic
Estimator
rosrun estimator my_estimator alt_topic:=range_topic estimate:=current_estimate

9. Exploration Path Planner
Concept
Define one node at a time using message interface
Blackbox everything else
Subscriber
Publisher
Kinect
Map
Exploration Path Planner
Altimeter
Estimator
IMU
/topic_name
Robot Control

10. Tools
ROS offers many built in tools that are helpful for collecting, visualizing, and processing data
rqt suite
rosbag tf
rviz
wstool

11. Tools
rqt_graph
Gives a graphical representation of the active nodes and topics

12. Tools
rqt_plot
Plots incoming messages on specified topics

13. Tools
rqt_bag & rosbag
rosbag records (subscribes to) specified topics and makes them available for playback (publishing)
useful for analysis and simulation
chatter
IMU
commands
states
goal
chatter
IMU
commands
states
goal
rosbag record topic_name
rosbag play bagfile.bag

14. Tools
rqt_bag
GUI access to rosbag
Selectively publish topics

15. Tools TF Keeps track of coordinate frames and transformations
Lookup transformations between different frames at specified times (including the past)
Does the math for you!!!

16. Tools
rviz
Visualize coordinate frames, point clouds, paths, goals, models, and much more

17. Useful wstool commands Free Version Control Sources
Tools
wstool
ROS tool to manage various version control sources
supports git, mercurial, subversion, bazaar
Useful wstool commands
wstool update
wstool status
wstool diff
wstool info
Free Version Control Sources
github.com
bitbucket.com
google it

18. Setup
Ubuntu LTS (
ROS Hydro (

19. Setup catkin workspace high level build manager
where your source code (packages) lives
cmake
lower level build manager
creates your .make file
catkin_ws/
build/
devel/
src/
CMakeLists.txt (never touch this)
package_one/
CMakeLists.txt (must be modified)
package.xml
msg/
msg1.msg
msg2.msg
source1.cpp
source2.cpp
include/
header.h
package_two/ …

20. Setup Qt Creator Qt is a power, easy to use IDE for C++ projects
Can be used for programming catkin packages
Installation on Ubuntu:
$ sudo apt-get install qtcreator
Opening Catkin Workspace with Qt Creator:
$ cd ~/catkin_ws/src
$ qtcreator CMakeLists.txt
It is easiest to run this from the command line so that Qt Creator has access to your required environment variables