ROS web Simple example

In this project there is a simple example how to use rosbridge server ands roslibjs to comunicate with ROS using yout web browser. The final objective is to create a simple html as a viewer that allow the browser to show params about the robot subscribed by means of ROS and it can publish specific data to simulate robot.

In this case, the robot will be a turtle thanks to turtlesim provide for ROS.

Requeriments

Assumes the following tools:

• ROS Kinetic running on Ubuntu 16.04
• Catkin tools

Help

It's important to know the environment around ROS and its basic structure. Read followings documents: DOC Folder

Simulator

To get started, It is advisable to do tests with TurtleSim

TurtleSim, this must be launch through the next command:

student@ubuntu:~$ rosrun turtlesim turtlesim_node build-essential

Structure

Ros workspace is catkin_ws and workspace where contain this example is robot_gui_bridge . Forto know as started ros project and starting to create your code , must look at the bottom of the page.

.
├── build
│   ├── catkin_tools_prebuild
│   │   ├── Makefile
│   │   ├── package.xml
│   │   └── test_results
│   └── robot_gui_bridge #This folder is created when lauch catkin_make or catkin build
├── devel
└── src #Folder where contain all our projects
    ├── CMakeLists.txt -> /opt/ros/kinetic/share/catkin/cmake/toplevel.cmake
    └── robot_gui_bridge
        ├── build
        │   ├── roslib.js
        │   └── roslib.min.js
        ├── CMakeLists.txt
        ├── gui
        │   ├── gui.html
        │   └── w3.css
        ├── launch
        │   └── websocket.launch
        └── package.xml

Creating a workspace

**This is a example where the new package (robot_gui_bridge) uses the dependencie rosbridge_server **

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws/src
catkin create pkg robot_gui_bridge --catkin-deps rosbridge_server
cd ~/catkin_ws

You could install the package manually using a command apt-get install ros-kinetic-rosbridge-server

Launch example

Before starting

sudo apt-get install ros-kinetic-tf2-tools

This is necessary because it must launch two turtlesim at once

Before to launch example you mitgh be make sure you have done the folllow commands:

catkin build # or catkin_make
source devel/setup.bash

Launch:

student@ubuntu:~/catkin_ws$ roslaunch robot_gui_bridge websocket.launch

student@ubuntu:~$ rosrun turtlesim turtlesim_node build-essential

Starting project in ROS

The next folder is created automatically when the installation of ROS is successful

student@ubuntu:~/catkin_ws/
student@ubuntu:~/catkin_ws/src$ catkin_create_pkg beginner_tutorials std_msgs rospy roscpp

After to create a package, you return to root project folder and:

student@ubuntu:~$ cd ~/catkin_ws
student@ubuntu:~/catkin_ws$ catkin build
student@ubuntu:~/catkin_ws$ . ~/catkin_ws/devel/setup.bash

Information about Building a ROS package here

If the codec that we want to launch if .py, add it ejecutable permission: student@ubuntu:~/catkin_ws/src/beginner_tutorials/src$ sudo chmod +x goto.py

Launch

1. Initialize

student@ubuntu:~$ roscore

What is rocore and because it's important? here

2. (goto.py works over turtle simulator)

student@ubuntu:~$ rosrun beginner_tutorials  beginner_tutorials/src/goto.py

Useful ROS commands

 student@ubuntu:~$ rostopic list
/client_count
/connected_clients
/rosout
/rosout_agg
/turtle1/cmd_vel
/turtle1/color_sensor
/turtle1/pose

student@ubuntu:~$ rostopic info /turtle1/pose
Type: turtlesim/Pose

Publishers: 
 * /turtlesim (http://ubuntu:37855/)

Subscribers: None