Bootstrap 4 framework allows you to create modern, great looking websites really quickly and without a big effort. It is currently one of the most popular front-end libraries for a reason. It is also open source and available under developer friendly MIT license. Building websites which not only look good but also scale well on different devices such as your laptop or a mobile phone is not a big deal with Bootstrap.

In this article I will show you how to use that framework together with ROS (Robot Operating System) — the most popular robotic middleware — to create awesome, intuitive web user interfaces for robots. I will guide you through setting-up the development environment, writing the code and running it on a physical robot. While in this article the demo is based on Husarion’s ROSbot 2.0 autonomous robot platform, you can easily run it on any other ROS powered and internet connected robot. It’s totally up to you.

Requirements

1. Laptop / PC with installed Visual Studio Code (VSC).

First, in VSC you need to install the following plugins:

Bootstrap 4, Font awesome 4, Font Awesome 5 Free & Pro snippets : this is the framework itself with couple of additional features which contain ready-to-use templates and other stuff useful while developing in bootstrap

: this is the framework itself with couple of additional features which contain ready-to-use templates and other stuff useful while developing in bootstrap Live Server : to see your web UI changes in realtime

: to see your web UI changes in realtime Prettier Code formatter : to keep your source code clean

: to keep your source code clean vscode-icons : to make your workspace look good

: to make your workspace look good Husarion (optional): to modify embedded firmware of CORE2 real-time robot control board without using cloud.husarion.com .

2. Physical robot or gazebo simulation model.

In this article we are using ROSbot 2.0, but you can use any other ROS robot that you have.

On top of standard ROS, you will need to install couple additional packages. To do that, in your robot Linux terminal run the following commands:

sudo apt update

and

sudo apt install python-tornado python-pip ros-kinetic-rosbridge-suite ros-kinetic-web-video-server nginx

Creating a web UI in VSC

1. Creating a new project

First create an empty folder (we named it ROS-bootstrap-demo ). Then start VSC and open the folder you just created. In VSC create a new file called named index.html . Thanks to one of the plugins for VSC which we have installed earlier creating a new Bootstrap 4 project is very straightforward. Just start typing b4 , then press ctrl + space for auto completion menu to appear and choose b4-$ . It will create a web page template with bootstrap libraries already included.

Here’s how creating a new project looks like:

Now right click the index.html file and select “Open with Live Server [Alt + L Alt + O]” option. You will see an empty page in your web browser . It will be updated automatically each time you save your project.

2. Writing the HTML code

Change the name of your page in the <title> tag to “ROS + Bootstrap 4 demo”: <title>ROS + Bootstrap 4 demo</title>

tag to “ROS + Bootstrap 4 demo”: Change the page background color to bg-light inside the <body> tag: <body class="bg-light">

inside the tag: Add some additional scripts above </body> tag:

First 3 scripts come from Robot Web Tools(http://robotwebtools.org/ ) . roslib.min.js is basic ROS javascript library, it allows your web apps to communicate with ROS system. eventemitter2.min.js is a support library for handling various ROS events. keyboardteleop.min.js is a support library for controlling the robot using the keyboard.

nipplejs.js is a library for creating a joystick for the web UI that is especially useful for controlling the robot on mobile devices.

And finally webui.js will be created in the next section of this article.

Below <body class="bg-light"> paste following code:

This is a basic structure of your app. In consists of a placeholder for the video, joystick and slider for selecting keyboard speed. Do not worry that <img> tag has an empty src parameter, it will be populated by javascript.

That is all for the html part, remember to save all the changes made in index.html .

3. Writing the JavaScript code

Create a new file, name it webui.js and save in the same folder as index.html .

Begin by creating some global variables:

Write a function to send ROS messages with velocity for robot:

Write a function to create velocity message publisher:

Write a function to create keyboard controller object:

Write a function to create joystick object:

…and finally main app initialization:

Choose between static IP address for the robot or dynamically defined IP with location.hostname depending on your configuration. If the web server is running on a device different than the robot, IP must be set manually to the robot address. If the app is deployed to a server which is running on your robot, it can be set automatically.

Video address string might need to be adjusted. Part /camera/rgb/image_raw is the topic name, where video is published by the robot. Set this topic according to your camera.

You web user interface is now ready.

Running the demo on your robot

1. Flashing default firmware to ROSbot 2.0 real-time board

This step is specific for ROSbot 2.0 platform. In case of other robots it may look different. What we are doing in this step is uploading the firmware to a STM32F4 MCU processor inside Husarion CORE2-ROS controller which is responsible for real-time tasks of our robot. CORE2-ROS is a computer inside ROSbot 2.0 and it’s basically a combination of ASUS Tinker Board single board computer and CORE2 real-time board.

The easiest way to upload a default firmware to ROSbot is to connect it to cloud.husarion.com , create a new project in WebIDE based on the template ROSbot default firmware , and click upload project to device ” button. This short video shows you how these steps look like:

2. Executing ROS nodes on your robot

Connect to your robot through SSH and execute the following commands in the Linux terminal (each in a separate terminal!):

roscore — ROS nodes will not be able to communicate without roscore. Each ROS system needs to have a roscore process running.

— ROS nodes will not be able to communicate without roscore. Each ROS system needs to have a roscore process running. rosrun web_video_server web_video_server — it launches the server for streaming ROS image messages as video through the web.

— it launches the server for streaming ROS image messages as video through the web. roslaunch rosbridge_server rosbridge_websocket.launch — it launches the web sockets to allow web apps to publish or subscribe ROS messages.

The commands bellow are specific for ROSbot 2.0 and for Orbecc Astra RGB-D camera. For other robots and cameras you will need to review the documentation of the devices you are going to use:

roslaunch astra_launch astra.launch — it starts a driver for Orbbec Astra RGB-D camera

— it starts a driver for Orbbec Astra RGB-D camera /opt/husarion/tools/rpi-linux/ros-core2-client /dev/ttyCORE2 — this is a bridge for communicating of CORE2 controller with ROS system. In this example, CORE2 is responsible for driving motors and estimating ROSbot position based on encoders. For different robot, you may need to switch this node to other driver.

3. Testing the web UI!

Now right click the index.html file and select “Open with Live Server [Alt + L Alt + O]” option. You should see a web user interface for your robot:

Deploying web user interface to the robot

Currently we’ve got a web user interface running on a PC, and in this step we will make it run on our robot.

Start with creating new folder on your robot and copy your app files to inside. On your robot edit Nginx configuration file by typing in:

sudo nano /etc/nginx/sites-enabled/default

find line:

root /var/www/html;

and change value /var/www/html to the path to your app. Restart Nginx:

sudo systemctl restart nginx

Nginx will start automatically at boot. You do not need to launch it again.

Open a web browser and type in your robots IP in the address bar. You should now see the UI which you have created (so cool!).