ROS cheatsheet.txt

ROS cheatsheet

* CONDA
- rqt will not work in conda environment
- conda deactivate # conda activate (to undo)

* File nav
rospack find [package_name] # get path to ros package
roscd <package or stack> # get to ros package
roscd log # get log
rosls package # list ros packages

* catkin workspace
catkin_make
- Example struct:
    workspace_folder/        -- WORKSPACE
      src/                   -- SOURCE SPACE
        CMakeLists.txt       -- 'Toplevel' CMake file, provided by catkin
        package_1/
          CMakeLists.txt     -- CMakeLists.txt file for package_1
          package.xml        -- Package manifest for package_1
        ...
        package_n/
          CMakeLists.txt     -- CMakeLists.txt file for package_n
          package.xml        -- Package manifest for package_n

* Create package
- Create package when in catkin_ws/src
catkin_create_pkg <package_name> [depend1] [depend2] [depend3] # create package, list dependencies (eg. catkin_create_pkg beginner_tutorials std_msgs rospy roscpp)
catkin_make # build packages in workspace
catkin_make --source my_src # build packages at specified location
. ~/catkin_ws/devel/setup.bash # add workspace to ROS environment

* Graph overview
- Nodes: A node is an executable that uses ROS to communicate with other nodes.
- Messages: ROS data type used when subscribing or publishing to a topic.
- Topics: Nodes can publish messages to a topic as well as subscribe to a topic to receive messages.
- Master: Name service for ROS (i.e. helps nodes find each other)
- rosout: ROS equivalent of stdout/stderr
- roscore: Master + rosout + parameter server (parameter server will be introduced later) 

* Nodes
- Executable that is connected to ROS network
roscore # create master
rosnode list # list nodes
rosnode info /rosout # get info on node rosout
rosrun [package_name] [node_name] # run node inside package
rosrun turtlesim turtlesim_node __name:=my_turtle # run node inside package & rename
rosnode cleanup # remove unused nodes
rosnode ping my_turtle # ping node

* Topics
- Topic is a channel for outputting and receiving info
- Publisher outputs info onto topic, subscribers listen to topic
rosrun rqt_graph rqt_graph # display graph of system
rostopic echo [topic] # show data published on topic
rostopic list -v # list topics (verbose)
rostopic type [topic] # get type of data for topic
rostopic type [topic] | rosmsg show # get type of data for topic, more info
rostopic pub -1 [topic] [msg_type] [args] # publish message to topic once
rostopic pub -r 1 [topic] [msg_type] [args] # publish message to topic every 1 second
rostopic hz [topic] # get data publish freq for topic

* Service
- Service is a channel for making requests, and sending responses
rosservice list # print information about active services
rosservice call [service] [args] # call the service with the provided args
rosservice type [service] # print service type
rosservice type [service] | rossrv show # print service type, more info
rosservice find # find services by service type
rosservice uri # print service ROSRPC uri

* Parameter server
- Way to store and manipulate data
rosparam set # set parameter
rosparam get # get parameter
rosparam get / # get all parameters
rosparam load [file_name] [namespace] # load parameters from file
rosparam dump [file_name] [namespace] # dump parameters to file
rosparam delete # delete parameter
rosparam list # list parameter names

* Debug
rosrun rqt_console rqt_console # open rqt console
rosrun rqt_logger_level rqt_logger_level # adjust verbosity of nodes

* Launch
roslaunch [package] [filename.launch] # launch node as specified by file

* Edit
rosed [package_name] [filename] # edit file in package

* srv and msg files
- msg files are simple text files that describe the fields of a ROS message
    Header header
    string child_frame_id
    geometry_msgs/PoseWithCovariance pose
    geometry_msgs/TwistWithCovariance twist
- srv file describes a service: a request and a response
    int64 A
    int64 B
    ---
    int64 Sum
rosmsg show [message type] # show message format
rossrv show <service type> # show service format
roscp [package_name] [file_to_copy_path] [copy_path] # copy file in package

* Help
- Using rosmsg as an example:
rosmsg -h # # list subcomands for rosmsg
rosmsg show -h # get info for subcommand

* Python
rospy.loginfo(str) - print str to console, node's log, and rosout
- constructor args are in the same order as in the .msg file
- Make sure you have sourced your workspace's setup.sh file after calling catkin_make: source ./devel/setup.bash

* C++
- If you have subscription in an application, and don't have ros::spinOnce(), your callbacks would never get called
- ros::spin() enters a loop, calling message callbacks as fast as possible; low CPU usage if nothing to do


* Workflow
- Install ROS (http://wiki.ros.org/ROS/Installation)
- Create workspace
    mkdir -p ~/catkin_ws/src
    cd ~/catkin_ws/
    catkin_make
- Create package in workspace/src
    cd catkin_ws/src
    catkin_create_pkg <package_name> [depend1] [depend2] [depend3]
    cd ~/catkin_ws
    catkin_make
    . ~/catkin_ws/devel/setup.bash
- Customize package
    - package.xml: modify description tag, maintainer tags, license tags, dependencies tags
       - <description>: Update description to be helpful
       - <maintainer email="user@todo.todo">user</maintainer>: Use your preferred email
       - <license>: pick license (eg. BSD)
       - <build_depend>, <buildtool_depend>, <exec_depend>, <test_depend>: may need to be added
- Build package
    source /opt/ros/noetic/setup.bash # already in ~/.bashrc
    cd catkin_ws
    catkin_make # catkin_make [make_targets] [-DCMAKE_VARIABLES=...]
- Create custom messages
    cd catkin_ws/src/<package>
    - Create and customize message:
       mkdir msg
       echo "int64 num" > msg/Num.msg
    - Update package.xml
       - Uncomment the following:
        <build_depend>message_generation</build_depend>
        <exec_depend>message_runtime</exec_depend>
    - Update CMakeList.txt
       - Add message_generation to find_package
         find_package(catkin REQUIRED COMPONENTS
            <dependencies>
            message_generation
         )
       - Add .msg to add_message_files
         add_message_files(
           FILES
           Num.msg
         )
       - Uncomment generate_messages
         generate_messages(
           DEPENDENCIES
           std_msgs
         )
       - Update CATKIN_DEPENDS in catkin_package
         catkin_package(
           CATKIN_DEPENDS message_runtime
         )
    - Check ROS can see your message
        rosmsg show <package>/Num
    - Make package
        cd catkin_ws
        catkin_make
        cd -
- Create custom service
    cd catkin_ws/src/<package>
    - Copy existing service:
       mkdir srv
       roscp rospy_tutorials AddTwoInts.srv srv/AddTwoInts.srv
    - Update package.xml
       - Uncomment the following:
        <build_depend>message_generation</build_depend>
        <exec_depend>message_runtime</exec_depend>
    - Update CMakeList.txt
        - Add message_generation to find_package
         find_package(catkin REQUIRED COMPONENTS
            <dependencies>
            message_generation
         )
        - Add .srv to add_service_files
         add_service_files(
           FILES
           AddTwoInts.srv
         )
        - Uncomment generate_messages
         generate_messages(
           DEPENDENCIES
           std_msgs
         )
    - Check ROS can see your service
        rossrv show <package>/AddTwoInts
    - Make package
        cd catkin_ws
        catkin_make
        cd -
- Python
    - Python goes in scripts:
        roscd <package>
        mkdir scripts
        cd scripts
    - Example code
        - Publisher
            - Get code
                wget https://raw.github.com/ros/ros_tutorials/kinetic-devel/rospy_tutorials/001_talker_listener/talker.py
                chmod +x talker.py
            - Update CMakeList.txt
                catkin_install_python(PROGRAMS
                  scripts/talker.py
                  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
                )
            - Build code
                cd ~/catkin_ws
                catkin_make
        - Subscriber
            - Get code
                wget https://raw.github.com/ros/ros_tutorials/kinetic-devel/rospy_tutorials/001_talker_listener/listener.py
                chmod +x listener.py
            - Update CMakeList.txt
                catkin_install_python(PROGRAMS
                  scripts/listener.py
                  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
                )
            - Build code
                cd ~/catkin_ws
                catkin_make
        - Server
            - Get code
                - http://wiki.ros.org/ROS/Tutorials/WritingServiceClient%28python%29
                - Create add_two_ints_server.py
                chmod +x add_two_ints_server.py
            - Update CMakeList.txt
                catkin_install_python(PROGRAMS
                  scripts/add_two_ints_server.py
                  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
                )
            - Build code
                cd ~/catkin_ws
                catkin_make
        - Client
            - Get code
                - http://wiki.ros.org/ROS/Tutorials/WritingServiceClient%28python%29
                - Create add_two_ints_client.py
                chmod +x add_two_ints_client.py
            - Update CMakeList.txt
                catkin_install_python(PROGRAMS
                  scripts/add_two_ints_client.py
                  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
                )
            - Build code
                cd ~/catkin_ws
                catkin_make
    - Execute Python nodes
        roscore
        cd ~/catkin_ws
        source ./devel/setup.bash
        rosrun <package> XXXX.py
- CPP
    - CPP goes in src:
        roscd <package>
        mkdir -p src
        cd src
    - Example code
        - Publisher
            - Get code
                wget https://raw.github.com/ros/ros_tutorials/noetic-devel/roscpp_tutorials/talker/talker.cpp
            - Add to CMakeList.txt
                add_executable(talker src/talker.cpp)
                target_link_libraries(talker ${catkin_LIBRARIES})
                add_dependencies(talker <package>_generate_messages_cpp)
            - Build code
                cd ~/catkin_ws
                catkin_make
        - Subscriber
            - Get code
                wget https://raw.github.com/ros/ros_tutorials/noetic-devel/roscpp_tutorials/listener/listener.cpp
            - Add to CMakeList.txt
                add_executable(listener src/listener.cpp)
                target_link_libraries(listener ${catkin_LIBRARIES})
                add_dependencies(listener <package>_generate_messages_cpp)
            - Build code
                cd ~/catkin_ws
                catkin_make
        - Server
            - Get code
                - http://wiki.ros.org/ROS/Tutorials/WritingServiceClient%28c%2B%2B%29
                - Create add_two_ints_server.cpp
            - Add to CMakeList.txt
                add_executable(add_two_ints_server src/add_two_ints_server.cpp)
                target_link_libraries(add_two_ints_server ${catkin_LIBRARIES})
                add_dependencies(add_two_ints_server beginner_tutorials_gencpp)
            - Build code
                cd ~/catkin_ws
                catkin_make
        - Client
            - Get code
                - http://wiki.ros.org/ROS/Tutorials/WritingServiceClient%28c%2B%2B%29
                - Create add_two_ints_client.cpp
            - Add to CMakeList.txt
                add_executable(add_two_ints_client src/add_two_ints_client.cpp)
                target_link_libraries(add_two_ints_client ${catkin_LIBRARIES})
                add_dependencies(add_two_ints_client beginner_tutorials_gencpp)
            - Build code
                cd ~/catkin_ws
                catkin_make
    - Executables located here at ~/catkin_ws/devel/lib/<package>
    - Execute CPP nodes
        roscore
        cd ~/catkin_ws
        source ./devel/setup.bash
        rosrun <package> XXXX