ROS Basic Tutorials

Linux-ROS Commands

• roscd - To switch to the main ros directory
• roscd [package_name] - To switch to the specific package inside the ros directory
• roscore - To run the main ros server
• rosnode list - To check the list of nodes that are running
• rostopic list - To check the list of topics that are running
• rosnode info [node_name] - To check all the details about the selected node
• rostopic info [topic_name] - To check all the details about the selected topic
• rosmsg show [msg_name] - To check all the details about the particular message that is being sent via topics
• rosservice list - To check the list of services that are running on
• rosservice info [service_name] - To check all the details about the service that is selected
• rossrv info [service_name] - To check all the details about the service that is selected
• rosservice call [service_name] [arguments] - To call the particular service on a running node
• roslaunch [package_name] [launch_file_name] - We can add all the nodes that we need to run in a launch file and run the launch file instead of single nodes.
• rosrun usb_cam usb_cam_node _pixel_format:=yuyv - To run the webcam in our laptop for ros related processes
• rosrun image_view image_view image:=/usb_cam/image_raw - To open the image view tool to access our webcam window and to see the output

ROS basic commands and CMake lists commands

Create a catkin package :

•  catkin_create_pkg <package_name> [depend1] [depend2] [depend3] 
  

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Making the Python file executable in cmakelists example :

•  catkin_install_python(PROGRAMS src/pub_sub_basics/talker.py
   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
   )
  

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Custom message adding in cmake lists example :

•   Generate messages in the 'msg' folder
    add_message_files(
    FILES
    IOTSensor.msg 
    )
  

• /Add "message_runtime" in catkin packages

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Custom service adding in cmake lists example :

•  add_service_files(
   FILES
   AddTwoInts.srv
   )
  

• /Check for message generation and message runtime in package.xml then add the service in srv folder

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Launch file syntax example :

•  <launch>
   <node name="turtlesim_node" pkg="turtlesim" type="turtlesim_node" output="screen"/>
   <node name="turtlesim_cleaner" pkg="beginer_tutorials" type="spiral.py" output="screen"/>
   </launch>
  

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OpenCV with ROS:

• /Install opencv and other tools.

•  sudo apt-get install ros-${distro_name}-opencv3
  

•  sudo apt-get install ros-${distro_name}-usb-cam
  

•  sudo apt-get install ros-${distro_name}-image-view
  

• /Now all the ros-opencv programs will be able to run without errors

• /See linux commands to run usb cam and image view

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