WVNC: web based protocol and API for accessing VNC server from browser via websocket

As with AntOS and its applications, one can remotely access and edit server resources from browser in a desktop-like manner. However, sometime these web based applications are not enough for some specific tasks. For a long time, I've thinking of a web based API for controlling remote desktop right from the browser ( or AntOS application). The VNC protocol is a good starting point. After playing around with libvncserver/libvncclient, i came up with wvnc a web based protocol and API for accessing VNC servers using websocket.

Controlling a Turtlebot using PhaROS: Goals planning and Automatic docking

This is a demonstration of my current work on controlling robot using ROS and PhaROS. For that task, I've developed a dedicated PhaROS package that defines:

  1. A base framework for ROS based visualization such as map, robot model, robot trajectory, etc.
  2. An Event-driven API for robot controlling
28/08/2018 ROS, SLAM, Metrics, evaluation, SSIM, MSE, NE

Evaluation of grid maps produced by a SLAM algorithm

When evaluating the performance of a SLAM algorithm, quantifying the produced map quality is one of the most important criteria. Often, the produced map is compared with (1) a ground-truth map (which can be easily obtained in simulation) or (2) with another existing map that is considered accurate (in case of real world experiment where the ground-truth is not always available ).

Basically, grid maps are images, so image similarity measurement metrics can be used in this case. In this post, we consider three different metrics: Mean Square Error (MSE), K-nearest based normalized error (NE) and Structure Similarity Index (SSIM)

AntOSDK tutorial: Developing a simple text editor

AntOS API in a nutshell

AntOS provides an abstract API for application development. The core API contains three main elements: the UI API, the VFS API and the VDB API, as shown in the following graph:

The UI API defines the basic UI elements such as Window, List, Tree, Dialogs, etc, and provides a generic interface for application and dialog UI development. UI design consists two steps: (1) the first step is to layout UI elements using antOS' scheme syntax (in XML format); (2) the second step is to handle user interaction using the coffeescript/ Javascript API.

Linux Tips and Tricks

This post contains some tips and tricks that helps resolve problems that i've encountered when working with Linux, mostly Ubuntu.

Ubuntu: Install 32 bits libraries on 64 bits system

Some of my applications are 32 bits only which sometime depend on several 32 bits libraries. By default, ubuntu installed only the 64 bits version of these libraries. To installed the 32 bit ones, we need enable the i386 architecture using dpkg, these following commands should be executed as root:

Simple (naive) document clustering using tf-idf and k-mean

When i developed this blog (using my own client-server platform such as web server, back-end, front-end, etc., built from ash/scratch :) ), i simply designed it as a simple "note book" where i put my ideas or some stuffs that i have done. So, initially, there are no category no advance feature like post suggestion based on current post, etc. It is just a bunch of posts sorting by date. The thing is, i usually work on many different domains (robotic, IoT, backend, frontend platform design, etc.), so my posts are mixed up between different categories. It is fine for me, but is a real inconvenience for readers who want to follow up their interesting category on the blog. Of course, i could redesign the blog and add the missing features by messing around with the relational database design (i'm using SQLite btw), manually classifying the posts in the back-end, etc. But, i'm a kind of lazy people, so i've been thinking of a more automatic solution. How about an automatic document clustering feature based on a data mining approach ? Here we go!

AntOS v 0.2.3-alpha release: AntOSDK - a development kit for AntOS application

A new release of AntOS, it is now in the beta state, but i'll keep the alpha branch on the release for a few further releases.

Change logs

  • Fix bugs and improve stability
  • DotEditor app is renamed to GraphEditor and use mermaid to generate graphs instead of dot
  • AntOS in now under GPLv3 licence, if you want to use it for comercial purpose, please contact me
  • Blogger is no longer default application, it is moved to MarketPlace
  • Add svg support to Preview
  • MarketPlace now can detect if an application update is available
  • Add AntoSDK, a development kit that allows to develop, build, and package your own application right in the browser, it is available on MarketPlace
  • New UI elements: afx-slider, tooltip

AntOS 0.2.0a "Localization" release

AntOS 0.2.0-alpha is out now. The big change in this release is the support of localization. The UI now support multi-languages rendering based on the current system locale setting.

Github: https://github.com/lxsang/antos
Demo: https://os.lxsang.me

Change logs

  • The API now automatically translate text base on the current system locale setting
  • Current locales supported:
    • English: en_GB
    • French: fr_FR
    • Vietnamese: vi_VN
    • More to come...
  • Update all packages to support the new localization mechanism
  • Some minor changes:
    • Font-awesome is used as default icon font for the entire system
    • Add Setting package for system configuration
    • Wallpaper, language, VFS and startup applications/services now can be configured via Setting
    • Bug fix on some packages: File, Market Place
    • Stability improvement

AntOS web desktop 0.1.11-alpha release

I've started the development of the AntOS web desktop long time ago, but this post is the first official pre-release of the project. The idea on a web-based desktop came when i worked on embed Linux and remote server. These system are often headless, so accessing the resource on these systems is not always obvious. The aim of this project is to develop a client core API that provides a desktop like experience to remotely access resource on the server using web technologies. AntOS is based on jQuery (for the API development) and Riot JS (for the UI), it is first designed to be used along with my antd HTTP(S) server and Lua based server side app, but can be adapted to be used with any server side languages (PHP, etc) and server, by implementing all the system calls API . Basically, application design for the web desktop relies on these system calls to communicating with the server. The API defines the core UI, system calls (to server), Virtual File system, virtual database and the necessary libraries for easing the development of applications. Applications can be developped with coffee/javascript/css without the need of a server side script.


(click image for the full size version)

Interfacing Raspberry Pi and LPC1114FN28 via SPI

In one of my previous posts, i mentioned about building a toy car project using Raspberry Pi as the brain and the LPC1114FN28 for low level control. This post describes in detail of this hobby project.

Basically, in this project, the Raspberry Pi (running a minimal version of Debian, not Rasbian) acts as a master that :

  1. performs some high level calculation (software algorithm) base on the data it collects from the LPC chip (slave)
  2. Issues a control command to the slave chip (LPC) for low level control
  3. Reading image from Raspberry Camera for some vision stuffs
  4. Takes care of network communication for remote control
  5. Implements easily a lot of funny stuffs...

One question: why do not use the Pi to communicate directly with sensor or actuator ?. Although the Pi is a pretty performance system, it lacks some low level feature that we will need in this project, such as ADC for reading analog sensors, precise PWM hardware controller for motor control, etc. Therefore, i decided to used it along with the LPC chip that is more suitable for these low level stuffs.

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