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A Very Brief ROS Tutorial

0.0 Installing Debian-based Linux distributions like Ubuntu.

Theoretically, you install ROS under any Debian-based Linux distributions. However, this tutorial is tested under Ubuntu 14.04 LTS.

0.1 Installing ROS

Here is the documentation for installation of Indigo and Jade. You can also install the latest version, but the codes in this tutorial are only tested with Indigo and Jade.

0.1 Installing Catkin Command Line Tools

Here is the documentation for catkin_tools.

1. Hellow World

Open a terminal window (ctrl+alt+t). Copy and paste the following codes to your terminal. Please modify the maintainer's name and email, and also the author's name and email.

# create catkin workspace
cd ~
mkdir -p catkin_ws/src
# initialize catkin workspace
cd ~/catkin_ws
catkin init --workspace .
# create ros package (hello_world)
cd src
catkin create pkg --rosdistro indigo -c roscpp rospy -l BSD -m maintainer_name [email protected] -a author_name [email protected] hello_world

Open your favorite editor (eg. Emacs) to edit the package.xml and CMakeLists.txt files if you did something wrong when you created the package or you want to add more information.

Create hello_world_node.cpp file with following contents.

// Include the ROS C++ APIs
#include <ros/ros.h>

// Standard C++ entry point
int main(int argc, char** argv) {
  // Announce this program to the ROS master as a "node" called "hello_world_node"
  ros::init(argc, argv, "hello_world_node");
  // Start the node resource managers (communication, time, etc)
  ros::start();
  // Broadcast a simple log message
  ROS_INFO_STREAM("Hello, world!");
  // Process ROS callbacks until receiving a SIGINT (ctrl-c)
  ros::spin();
  // Stop the node's resources
  ros::shutdown();
  // Exit tranquilly
  return 0;
}

Modify corresponding parts in the package.xml and CMakeLists.txt so that the catkin tools can help you to compile the executables correctly.

You can specify additional locations of header files, declare C++ executables and anything else you want to control in the Build part of the CMakeLists.txt file. For example, in this example, we only need to declare one C++ exectable named hello_world_node and link the catkin library to the exectable.

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
# include_directories(include)
include_directories(
  ${catkin_INCLUDE_DIRS}
)

## Declare a C++ library
# add_library(hello_world
#   src/${PROJECT_NAME}/hello_world.cpp
# )

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(hello_world ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable
add_executable(hello_world_node src/hello_world_node.cpp)

## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(hello_world_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
target_link_libraries(hello_world_node
  ${catkin_LIBRARIES}
)

It is not necessary to modify anything in the package.xml in this example. However, if you have multiple packages and some of the packages have sort of dependents on the other packages, you can modify the package.xml file to tell the catkin tools the dependent relationship of all the packages.

You should have a similar architecture tree as follows.

my_catkin_ws/
└── src
    └── hello_world
        ├── CMakeLists.txt
        ├── include
        │   └── hello_world
        ├── package.xml
        └── src
            └── hello_world_node.cpp

Now you are ready to compile the ROS package by catkin tools using the following command.

# add ROS environment variables to your current bash session (modify indigo to jade if you are using jade)
source /opt/ros/indigo/setup.bash
# build the package
catkin build hello_world

After compiling the package, you can launch the ROS node. Please do remember to launch the roscore before executing the node.

# add catkin workspace environment variables to your current bash session
source ~/catkin_ws/devel/setup.bash
# run the node (executable)
rosrun hello_world hello_world_node

By running the node, you should be able to observe the following results in your terminal.

[ INFO] [1475573239.386991148]: Hello, world!

2. Turtlesim

Clone the package from GitHub.

# change directory to the package src folder
cd ~/catkin_ws/src
# clone the repository from github, and copy the specific package to the package source directory
git clone https://github.com/ros/ros_tutorials.git
cp -r ros_tutorials/turtlesim/ .

Build the package.

#
# add ROS environment variables to your current bash session (modify indigo to jade if you are using jade)
source /opt/ros/indigo/setup.bash
# build the package
catkin build turtlesim

3. Video Pipeline

Clone the package from GitHub.

cd ~/catkin_ws/src
git clone https://github.com/zrwang/hauppauge.git
catkin build hauppauge