Package Organization

Package Structure

    ws_catkin
    ├── devel
    ├── build
    └── src
        └── package_name
            ├── CMakeList.txt
            ├── package.xml
            ├── arduino           --- arduino_sketch.ino
            ├── config            --- config.yaml
            ├── doc               --- pdf jpg
            ├── include
            │   └── package_name  --- cppheader.h
            ├── src               --- cppsource.cpp
            ├── scripts           --- python_script.py
            ├── launch            --- launch_file.launch
            ├── action            --- action.action
            ├── msg               --- msg.msg
            ├── srv               --- srv.srv
            ├── rviz              --- rviz_config.rviz
            ├── test              --- unitest.cpp/.py
            └── gazebo
                ├── meshes        --- model.STL/.dae
                ├── models        --- model.config/.sdf/.urdf
                ├── urdf          --- model.xacro/.gazebo
                └── worlds        --- model.world

Workspaces and Package

Create Workspace

    mkdir catkin_ws && cd catkin_ws
    wstool init src
    catkin_make
    source devel/setup.bash

Add Repo to Workspace

    roscd; cd ../src
    wstool set repo_name \
    --git http://github.com/org/repo_name.git \
    --version=melodic-devel
    wstool up

Resolve Dependencies in Workspace

    sudo rosdep init  # only once
    rosdep update
    rosdep install --from-paths src --ignore-src \
    --rosdistro=${ROS_DISTRO} -y

Create Package

    catkin_create_pkg package_name [dependencies ...]

CMakeList.txt

Skeleton

    cmake_minimum_required(VERSION 2.8.3)
    project(package_name)
    find_package(catkin REQUIRED)
    catkin_package()

Package Dependencies

    find_package(catkin REQUIRED COMPONENTS roscpp)
    Tell dependent packages what headers or libraries to pull in when your package is declared as a catkin component:
    catkin_package(
      INCLUDE_DIRS include
      LIBRARIES ${PROJECT_NAME}
      CATKIN_DEPENDS roscpp)

Messages, Services

    find_package(catkin REQUIRED COMPONENTS message_generation std_msgs)
    add_message_files(FILES MyMessage.msg)
    add_service_files(FILES MyService.msg)
    generate_messages(DEPENDENCIES std_msgs)
    catkin_package(CATKIN_DEPENDS message_runtime std_msgs)

Build Libraries, Executables

    add_library(${PROJECT_NAME} src/cpp_code.cpp)
    add_executable(${PROJECT_NAME}_node src/cpp_code.cpp)
    target_link_libraries(${PROJECT_NAME}_node ${catkin_LIBRARIES})
    add_dependencies(${PROJECT_NAME} beginner_tutorials_generate_messages_cpp)

Installation

    install(TARGETS ${PROJECT_NAME} DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION})
    install(TARGETS ${PROJECT_NAME}_node DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION})
    install(PROGRAMS scripts/myscript DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION})
    install(DIRECTORY launch DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION})

Remote Connection

To connect remotely, ensure the following:

Master’s ROS environment:

ROS_IP or ROS_HOSTNAME set to this machine’s network address.
ROS_MASTER_URI set to URI containing that IP or hostname.

Your environment:

ROS_IP or ROS_HOSTNAME set to your machine’s network address.
ROS_MASTER_URI set to the URI from the master.

To debug, check ping from each side to the other, run roswtf on each side.

Command Line Interfaces

Command	Description
`rosnode list`	List available ROS nodes
`rostopic list`	List available ROS topics
`rostopic echo /topic_name`	Print out data in topic name
`rostopic hz /topic_name`	Calculate frequency of topic
`rostopic info /topic_name`	Show information of topic
`rosmsg show message_msgs/msg_name`	Show information of data in ROS message
`rospack find {package_name}`	Find the location of the package
`rospack depends {package_name}`	Find the packages that the package depends on
`rospack help`	Show description of rospack
`rosrun rqt_graph rqt_graph`	Show rqt graph
`roscd {package_name}`	Change directory to ROS package in system
`rosls {package_name}`	List content in the directory
`find . -name".py" -exec chmod +x {} \;`	Find all files ending in .py and make them executable