ROS Beginner's Tutorial

Overview

Simple project to get started with ROS:

• Contains a beginner level tutorial as a ROS package to establish communication between 2 ROS nodes
• Employs rosservice feature to change the broadcated message between the nodes
• Uses TF frames, roslaunch, and rostest capabilities
• Developed over 4 weeks:
  • The first week was only to get started with listener-talker nodes.
  • In the second week, rosservice, roslaunch, and rqt_graph features were added.
  • The third week was to use rosbag and rostest features.
  • The last week was to get continuous integration included in the repo using Travis CI.

Dependencies

• Ubuntu 16.04
• ROS Kinetic

Install Dependencies

• This project was developed using ROS Kinetic.
• It is highly recommended that ROS Kinetic is properly installed on your system before the use of this project.
• Follow the instructions on this link to install full-desktop version of ROS Kinetic.
• Check the version of ROS to ensure successful installation.

rosversion roscpp

• It should output:

1.12.14

• Create your ROS workspace by following instructions on this link.

Build

• Switch to your src sub-directory of your ROS workspace to clone this repository.

<ROS Workspace>/src

• Run the following commands to clone and build this project:

git clone --recursive https://github.com/urastogi885/beginner_tutorials
cd ..
catkin_make

Run

• In the same terminal, run:

roscore

• Open a new terminal, switch to the ROS workspace, and run both the nodes using the roslaunch:

cd <ROS Workspace>
source devel/setup.bash
roslaunch beginner_tutorials service.launch rate:=<frequency(Hz) in integer> enableRosBag:=false

• For example:

roslaunch beginner_tutorials service.launch rate:=2 enableRosBag:=false

• Open another new terminal, switch to the ROS workspace, and run service to change the publishing message:

cd <ROS Workspace>
source devel/setup.bash
rosservice call modifyMessageService <integer>

• The message-manipulator service takes an integer as an input if the number is even message is concatenated twice otherwise it is concatenated thrice.
• For example:

rosservice call modifyMessageService 5

Inspect TF Frames and Tree

• In a new terminal, switch to the ROS workspace, and run these commands to view TF frames, tree, and transform:

cd <ROS Workspace>
source devel/setup.bash
rosrun tf view_frames
evince frames.pdf
rosrun rqt_tf_tree rqt_tf_tree
rosrun tf tf_echo world talk

• The last command will keep publishing the transform of the talk frame with respect to the world frame.
• Press Ctrl+C to stop running the command.
• The output of each of the above commands is included in the result sub-directory. A list of files in the folder is given below in the Documents section.

Generate Rosbag File

• You can either generate a new ROS bag file or play the rosbag file included in the result directory.
• To generate a new bag file, launch all the ros nodes. (You can skip this step if you just want to play the previously generated bag file)

roslaunch beginner_tutorials service.launch rate:=<frequency(Hz) in integer> enableRosBag:=true

• For example:

roslaunch beginner_tutorials service.launch rate:=2 enableRosBag:=true

• The bag file would have been replaced with new data.
• To play the ROS bag file, terminate the talker and listener nodes, and run:

rosrun beginner_tutorials listener

• In a new terminal, and switch to the result sub-directory in the project directory: (Make sure roscore is running)

cd <ROS Workspace>/src/beginner_tutorials/result
rosbag play recordTalker.bag

• All the messages stored in the bag file will be published on the listener node.
• You can also verify the bag file by running: (Stop the execution of last command before proceeding any further by using Ctrl+C)

rosbag info recordTalker.bag

Test

• Make sure all the ROS nodes have been terminated, including ROS master, and close all the terminal windows.
• In a new terminal, switch to the ROS workspace, and build the tests:

cd <ROS Workspace>
source devel/setup.bash
catkin_make run_tests_beginner_tutorials

• The above command will also run the tests after building them.
• After build, the following command can also be used to run all the test cases:

rostest beginner_tutorials modifyMessageTest.launch

• You should be able to see the successful execution of 2 test cases.
• A screenshot of the execution of the test cases is included in the result directory.

Documents

• These are located in the result sub-directory:
  • Cpplint - cpplint_output.txt
  • Cppcheck - cppcheck_output.txt
  • RQT Console - rqt_console_output.png
  • TF Frame Output- frames.pdf
  • RosBag - recordTalker.bag
  • Rosbag Play - rosbag_play.png
  • RQT Tree - rqt_tree.png
  • RQT TF Echo - rqt_tf_echo.png
  • Rostest Output - rostest_output.png