beginner_tutorials

Overview

A beginners tutorial for ROS Publisher and Subscriber using C++. This repository contains a simple tutorial to work with ROS Publisher and Subscriber to understand their roles in ROS.

Dependencies

Ubuntu 18.04 LTS
ROS Melodic
Modern C++ Programming Language
Roscpp Package
Std_msgs Package
Message_generation Package
Catkin_Make Build System

Build

Create a Catkin Workspace and cd into it

cd ~/catkin_ws
catkin_make

Clone the repository

cd src
git clone https://github.com/iamjadhav/beginner_tutorials.git

Run

In a New Terminal, run the code using launch file

cd ~/catkin_ws
catkin_make
source devel/setup.bash
roslaunch beginner_tutorials begin_tutorials.launch

Running with a frequency different than the default: just change the last command to,

roslaunch beginner_tutorials begin_tutorials.launch frequency:="<desired frequency>"

ROS Service

In a New Terminal (while the nodes are running), type

cd ~/catkin_ws
source devel/setup.bash
rosservice call /AddTwoFloats "a: <float of your choice> b: <float of your choice>"

Inspecting ROS TF Frames

To view the transform between the world and talk frames: in one terminal,

launch the nodes from the catkin_ws using the launch file

and in another terminal, type,

cd ~/catkin_ws
rosrun tf tf_echo world talk

And for creating a diagram of the frames: in the same terminal after tf_echo , type,

rosrun tf view_frames
evince frames.pdf
rosrun rqt_tf_tree rqt_tf_tree

frames.pdf will be saved in the package which contains the view_frames result.

Tests

To run the tests: In a new terminal, type,

cd ~/catkin_ws
source devel/setup.bash
catkin_make run_tests_beginner_tutorials

OR to run the tests with the launch file: In a new terminal, type,

cd ~/catkin_ws
source devel/setup.bash
rostest beginner_tutorials AddTwoFloatsTest.launch

ROSBAG

Recording a bag

The rosbagEnable argument is disabled by default. To record a rosbag: launch the nodes with the following commands,

cd ~/catkin_ws
catkin_make
source devel/setup.bash
roslaunch beginner_tutorials begin_tutorials.launch rosbagEnable:=true

Playing the bag

To play a rosbag: while the nodes are launched OR a separate roscore is running,

in a different terminal, cd to the directory where rosbags are stored and type,

cd cakin_ws/src/beginner_tutorials/results
rosbag play recordedbag.bag

To play a rosbag with the listener demo: in one terminal, type,

cd cakin_ws/src/beginner_tutorials/results
rosbag play recordedbag.bag

and in a different terminal, type,

cd ~/catkin_ws
rostopic echo /chatter

Inspecting the bag

To inspect a recorded bag file: cd into the directory where rosbags are stored and type,

rosbag info recordedbag.bag

iamjadhav / beginner_tutorials Goto Github PK