IBus (Intelligent Input Bus for Linux/Unix OS) become the main Language Input Method manager since Ubuntu 9.10. For Vietnamese people and ones who want to learn and type Vietnamese language, unikey is usually the best choice in Windows and Linux as well. This article is going to guide to install ibus-unikey in Ubuntu.

Ibus-Unikey package is maintained by Ubuntu-VN community, so ibus-unikey or scim-unikey is always in their PPAs. So we can easily install and get package update whenever the new version is released.

Add Ubuntu-VN repository

For Ubuntu from 9.10, Ubuntu 10.04, just open Terminal and type this command:

$sudo add-apt-repository ppa:ubuntu-vn/ppa

Update system and install ibus-unikey

Next, just update your system:

$ sudo apt-get update

And insall ibus-unikey package:

sudo apt-get install ibus-unikey

DONE. Now you can choose to add Unikey in the Vietnamese language selection of IBus Preferences.

I am currently doing one project about Mobile Robot Teleoperation, so stream video over network is one of my part. Actually there are many different approaches, but I chose OpenCV as my main approach because of its advantages in term of Computer Vision. But the crazy thing I have to do is making 2 server and client programs which run in Windows and Linux, respectively. Ok, now let’s go together:

Install OpenCV

OpenCV (Open Source Computer Vision) is a library of programming functions for real time computer vision.

• OpenCV is released under a BSD license, it is free for both academic and commercial use.
• The library has >500 optimized algorithms (see figure below). It is used around the world, has >2M downloads and >40K people in the user group. Uses range from interactive art, to mine inspection, stitching maps on the web on through advanced robotics.

For more information, go to OpenCV Wiki. It is not difficult to build OpenCV in Linux, just base on Install Guide but make sure that install all Prerequisites: Python, Intel TBB, …

In Windows counterpart, I can easily build OpenCV using Microsoft Studio, but I am using program which has multi-thread (POSIX) feature, so I can’t use this library for that. So I prefer to build OpenCV using Cygwin, but I didn’t get success yet :d. So what I have done with that ?

• Download OpenCV-2.1.0-win32-vs2008.exe and install it
• Download OpenCV libs compiled by Cygwin and put it to the /bin and /lib from Python OpenCV project. Just download opencv210_mingw.7z

And don’t forget to install Cygwin and needed packages like gcc, make, cmake, … before that

Program

This post describes very well about what do you have to do with OpenCV and socket programming. Thank Nashruddin for great effort. But I would like to contribute some things here: cmake list and delay function.

I really love Cmake so much, it is very handy and powerful tool for cross platform applications. If you don’t know what is Cmake, have a look at http://cmake.org/, you will love it for sure.

In the folder which has your source code, just create a file named CMakeLists.txt. For the server part it will be:

project(MobileApp)
cmake_minimum_required(VERSION 2.6)
# Find OpenCV package
FIND_PACKAGE(OpenCV REQUIRED)
# Vision program
add_executable(stream_server stream_server.c)
target_link_libraries(stream_server ${OpenCV_LIBS})

REQUIRED
For the client counterpart:

project(MobileApp)
cmake_minimum_required(VERSION 2.6)
# Find OpenCV package
FIND_PACKAGE(OpenCV REQUIRED)
# Vision program
add_executable(stream_client stream_client.c)
target_link_libraries(stream_client ${OpenCV_LIBS})

To build the application, follow these steps:

$ mkdir build
$ cd build
$ cmake ..
$ make

cmake will automatically generate your Makefile based on your system configuration, so whenever you move it to other computer or other platform it will check again.

Note: there is one issue that cmake couldn’t understand the parameter OpenCV_LIBS even thought it can detect OpenCV libs, so you need to add OpenCV libs by using other variable OpenCV_DIR.So you need to change ${OpenCV_LIBS} to ${OpenCV_DIR}/libs. Have a look at FindOpenCV.cmake

I am doing a project about Mobile Robot Teleoperation which uses OpenCV for Computer Vision, but I always get error: libdc1394 error: Failed to initialize libdc1394

The reason is: There is no file /dev/raw1394 since the raw1394 driver is not loaded. So you need to insert that driver:

$ sudo modprobe raw1394

Check your permission access to that dev file:

$ ls -la /dev/raw1394

If you don’t have rw access right, need to change that permissons:

$ sudo chmod a+rw /dev/raw1394

Credit for Viktors Petrovs from this bug

I am usually using Facebook and Twitter together, so sometimes I feel lazy to post what I am doing to both Facebook and Twitter so I was always looking for a good application which can automatically post my Twitter Updates to Facebook. Finally I was so satisfied with this Twitter application.

But by time it is really annoying that every my Twitter updates show up in Facebook, and my friends always said I am a spammer ^-^, but couldn’t know how to prevent it to steal my updates until today.

What do you have to do ?

- Go to that application
- You can see the option Block this application. Just click that link, so your Twitter updates will no longer be posted in Facebook.

I am a Twitter fan so far, so I have been always looking for good enough tools to make up my Twitter background. Today, after working, just spent little time I can have a overview of those tools, thanks to hongkiat.com article.

Is the default blue background of your Twitter page starting to look stale, or is it just me? It’s time to spice up your Twitter page with a little more personality – a little more YOU! With the growing trend of Twitter usage, it’s only logical to treat Twitter as an impression of yourself. And as you would personalize the profile picture of your Facebook, why leave your Twitter as one of the faceless crowd?

Just choose one suitable tool for you from here

For me, I choose http://www.freetwitterdesigner.com to design my background. That online tool works like a online Photoshop program, so I can easily design make my own background. Just have a look http://twitter.com/ngohaibac

At this moment, I am using one Windows Server 2008 running on an VPS (Virtual Private Server). Like before, I always want to setup system by myself to make sure to know what is on my system. The first time, I was thinking to use Linux server, but I changed my mind at last to choose Windows since uTorrent runs very well and is supported and recommended on almost well-known Private Torrent Trackers such as hd-torrents, bit-hdtv, bitme, bitspyder, … I can use XAMPP since I am very familiar with, but I just wanted to face with Windows stuff

I will briefly introduce some steps that you need to go though.

1. Need to install IIS7 and setup Web Server (if you want to share data through HTTP protocol) and FTP Server 7.5 based on these tutorials from IIS

• Planning Your IIS 7 Architecture
• Installing and Configuring IIS 7
• Deploying Web Sites on IIS 7
• Managing and Maintaining IIS 7
• Developing on IIS 7
• Hosting Applications on IIS 7
• Serving Media Content
• Microsoft Web Platform
• Hosting Guidance for the Microsoft Web Platform
• Localized Content

2. The above steps are not difficult, they can be done around 30mins or 1h included waiting time. But the most difficult task is finding the way to configure Windows firewall for FTP Server even read this steps many times.

FTP Server has data channel and control channel (usually 21), so we need to forward all needed ports though Windows firewall. Below is setting for FTP Data channel Port Range:

If in Windows Firewall configuration, you just allow port 21, you can use command to list data, but you can’t read data since there is only one port for that. When I used FireZilla I got this message:

Error: Could not read from socket: ECONNRESET – Connection reset by peer
Error: Disconnected from server
Error: Failed to retrieve directory listing

So one important step here is let Windows Firewall understand and allow the FTP assigned ports by run those commands under Command Prompt as Administrator: (base on this help)

netsh advfirewall firewall add rule name=”FTP Service” action=allow service=ftpsvc protocol=TCP dir=in

And disable stateful FTP filtering so that the firewall does not block any FTP traffic:

netsh advfirewall set global StatefulFTP disable

So now I can enjoy download files from my server

Last week, I have introduced to RealTime Application Interface for Linux, now I would like to give you some RTAI Conference Papers. Those papers could be a very good reference for everyone who is working with RTAI, as well as people doesn’t play with RTAI before to have more motivation.

1. PC-based feedback acceleration control using Linux RTAI

ABSTRACT
Linux operative system, extended with the real time application interface (RTAI), makes it possible to realize industrial motion controls. This requires general purpose processors (GPPs) instead of dedicated DSPs or microcontrollers. RTAI offers the possibility of designing and developing motion controls using high level object languages (i.e., Simulink). The main advantages brought using Linux-RTAI and a PC as a controller platform are: very reduced time for development, diagnostics, design of controls; cost reduction offered by the open-source status of the operating system; high availability of the hardware. This paper shows that such a system offers adequate digital programming and signal processing capabilities to make real time motion control applications. An industrial-PC based acceleration control is presented and points of strength of RTAI solution are shown.

2. Industrial motion control applications using linux RTAI

ABSTRACT
RTAI extension to Linux operating system makes it possible to perform Hard Real-Time (HRT) controls using a commercial PC and utilizing open-source code. This paper details a software installation process, along with the suitable hardware chosen for realizing motion controls using Linux-RTAI. Advantages offered by the possibility of designing and developing motion controls using the powerful tools of high level object-languages (i.e. Simulink) are described. It is proven that the combination of Simulink as a development environment and Linux-RTAI PC as a controller platform brings advantages that can be greatly appreciated in industrial motion control applications, such as: very reduced time for development, diagnostics, design of controls; adequate control performance; cost reductions offered by the open-source status of the operating system.

3.Scilab/Scicos and Linux RTAI – a unified approach

ABSTRACT
This paper presents a rapid controller prototyping environment completely based on open source software. GNU/Linux with the RTAI extension is used as a hard real-time operating system. The Scilab/Scicos suite permits performance of all phases of the control system design. A modified Scicos code generator directly generates the C-code for the Linux RTAI environment. Finally, the generated hard real-time task runs as a user space application on a standard PC using the COMEDI drivers to interface with the real plant. A GUI application facilitates the user to interact with the running real-time task (data visualization, data collection, parameters tuning) directly from any PC in the network. All needed software is available on the Web and can be freely downloaded. Some applications are presented to demonstrate the potentialities of the presented suite.

4. A Hardware-In-the-Loop Simulation System of Diesel Engine Based on Linux RTAI

ABSTRACT
In this article, the rapid prototyping technology is used to develop a hardware-in-the-loop simulation system for the diesel engine electronic control unit development. The hardware- in-the-loop simulation is based on Linux RTAI system, an open source hard real-time extension of the Linux Operating System, at low costs and within industrial standards. It exploits standard x86-based computing platforms provided with real-time Linux software in combination with generic computer-aided design software (Matlab/Simulink). One of its main characteristics is that it can automatically generate the real-time simulation code for many target processors, which runs under Linux RTAI operating system.

5.Monitoring applications of electrical and climate data for PV systems using Linux RTAI

ABSTRACT
This work presents the design and development of an innovative system aimed at detecting, recording and transmitting electrical and climate data from a PV field. Data are to be taken both from the PV modules and from the power conditioning system of a given PV field, through appropriate sensors, to monitor: climate data (irradiance, temperature), electrical quantities (voltage, current, power), performance of the PV generator as a function of climate parameters, performance of the power conditioning system over different working conditions. The system will exchange data through a communication network (i.e. Ethernet/TCP-IP) to download data, visualize quantities and operative states. The proposed system is designed to be integrated into any PV field, independently from the plant layout, the inverter type, the presence of preexisting data loggers, sensors, etc. Such a result is achieved using an open architecture, which assures an extremely high flexibility of utilization.

6.Real time distributed control systems using RTAI

ABSTRACT
The paper outlines the design and implementation of the Real Time Application Interface (RTAI) for Linux, as used for high performance local/distributed control systems implemented on low cost off the shelf general purpose computers. Its native lean real time middleware layer is described along with its use in an advanced tool to easily manage and monitor complex networked control systems.

7. RTAI-based execution environments for function block based control applications

ABSTRACT
The IEC 61499 standard has been recently adopted to promote a more flexible development process in the control and automation domain. The standard mainly deals with modeling issues leaving a lot of model execution details open. Different research groups are already working for the development of execution environments for the defined component model, proposing implementations with different execution semantics. This paper discuss the semantics of the execution environment and presents two execution environments, which although independently developed share a similar view of IEC61499 execution semantics and are both implemented over RTAI (real time application interface), a real-time Linux-based platform.

8. Performance Comparison of VxWorks, Linux, RTAI and Xenomai in a Hard Real-time Application

ABSTRACT
We report on a set of performance measurements executed on VMEbus MVME5500 boards equipped with MPC7455 PowerPC processor, running four different operating systems: Wind River VxWorks, Linux, RTAI, and Xenomai. Some components of RTAI and Xenomai have been ported to the target architecture. Interrupt latency, rescheduling and inter-process communication times are compared in the framework of a sample real-time application. Performance measurements on Gigabit Ethernet network communication have also been carried out on the target boards. To this purpose, we have considered the Linux IP stack and RTnet, an open-source hard real-time network protocol stack for Xenomai and RTAI, which was ported to the considered architecture. Performance measurements show that the tested open-source software is suitable for hard real-time applications

9. RTAI-based execution environments for function block based control applications

ABSTRACT
The IEC 61499 standard has been recently adopted to promote a more flexible development process in the control and automation domain. The standard mainly deals with modeling issues leaving a lot of model execution details open. Different research groups are already working for the development of execution environments for the defined component model, proposing implementations with different execution semantics. This paper discuss the semantics of the execution environment and presents two execution environments, which although independently developed share a similar view of IEC61499 execution semantics and are both implemented over RTAI (real time application interface), a real-time Linux-based platform.

10. Rapid control prototyping with Scilab/Scicos/RTAI for PC-based ARM-based platforms

ABSTRACT
This document describes three didactic system with a Rapid Control Prototyping (RCP) suite based on Scilab/Scicos and a PC computer. Servomechanisms with wire signal transmission and PID as well as a fuzzy controller are presented. The servomechanism with wireless signal transmission is also described. As the RCP suite based on Scilab/Scicos/RTAI was successfully used in the servo controller development on a PC platform, the concept of a tool-chain for RCP on an embedded platform with ARM processor is discussed. The TS-7300 embedded system with RTAI real-time operating system is described. The changes in Scilab/Scicos needed to interface the generated controller code to TS-7300 are presented. The didactic use and a possible commercial use of the tool-chain is indicated. The didactic use is focused on controllers tuning, friction and long delays influence on servomechanism control and embedded control system development.

Note: They are all papers I have downloaded and read, so I just share it with the one who wants it.

What is CHM ?

Let’s have a look at Wikipedia:

Microsoft Compiled HTML Help is a proprietary format for online help files, developed by Microsoft and first released in 1997 as a successor to the Microsoft WinHelp format. It was first introduced with the release of Windows 98, and is still supported and distributed through Windows XP and Vista platforms.

“.chm” is one kind of headache for Linux users so let’s find the best useful CHM viewer for Ubuntu/Linux. I have some great eBooks but in CHM format, so I have been always finding a good and useful CHM Viewer for my system.

My requirements of a CHM Viewer program include:

• Be able to read .chm file (of course)
• Good looking
• Support non-English language
• Still under development since by time new Ubuntu version releases, so it may have some bugs when we upgrades our systems.

Let’s go to Applications, Ubuntu Software Center and type chm you could see there are 5 available CHM viewer  apps in Ubuntu server:

• xCHM
• E-Book reader
• CHM Viewer
• Chmsee
• KchmViewer

They are all active projects, but I did have a look at all features and tried all but only KchmViewer can satisfy  me. Let’s have a look at its features

Kchmviewer is a free, open-source chm (MS HTML help file format) viewer written in C++ for Unix, Mac and Windows systems. Unlike most existing CHM viewers for Unix, it uses Trolltech Qt widget library, and could optionally be compiled for better KDE integration. It does not require KDE, but may be compiled with full KDE support, including KDE widgets and KIO/KHTML.

The main advantage of kchmviewer is the best support for non-English languages. Unlike other viewers, kchmviewer in most cases is able to correctly detect the chm file encoding and show it. It correctly shows the index and table of context in Russian, Spanish, Romanian, Korean, Chinese and Arabic help files, and with new search engine is able to search in any chm file no matter what language it is written.

kchmviewer is written by George Yunaev (see the contacts page for details), and is licensed under GNU GPL license. It uses chmlib, and some ideas and code from xchm.

You can have a look at here in more detail. I can give you some reasons why I love this app more than others:

• Written by using QT Library which is the best cross-platform library. You will feel that each button and edges are very smooth and clean.
• Support non-English languages
• Can view .chm files in tabs. I am always tired of managing a lot of opened files in desktop, so this feature helps me a lot then

How to install KChmViewer

Just open Terminal:

sudo aptitude install kchmviewer

and type your super user password, and enjoy the program by going to Applications >> Office

Skype is a software to make free video and voice calls, send instant messages and share files with other Skype users. You can use Skype in almost famous platforms: Windows, Linux, Mac OS and for your mobiles as well. For Linux users, you can easily download and install Skype binary package from here.

With the 32-bit Ubuntu box, you simply just plug Webcam or use build-in webcam, turn Skype and enjoy chatting with your girlfriend, however with the 64-bit counterpart, you have to do some tricks to make it works. Otherwise, you can’t see anything even you still can see camera file in /dev/video0

1. You have to locate v4l1compat.so library in your system. User Terminal and type this:

$ find / -name v4l1compat.so 2>/dev/null
/usr/lib/libv4l/v4l1compat.so
/usr/lib32/libv4l/v4l1compat.so

Use /dev/null to ignore errors can appear during searching for that lib.

2. You then have to load that library before other Skype libs by using LD_PRELOAD. You can read this article to see how LD_PRELOAD works: Modifying a Dynamic Library Without Changing the Source Code

So now create a file in anywhere you like with this folowing content:

#!/bin/bash
LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so /usr/bin/skype

And don’t forget to set execute permission to that file (chmod u+x ./yourfile).

Nowadays, people is looking for RealTime solutions for their products, since their tasks have to be done very accurately. One more reason is Linux OS usually to be integrated into embedded IC ( Arm, PowerPC, … ). In term of Realtime OS, there are several wellknown Real-Time OS: QNX, VxWorks, RTAI.

VxWorks comes from WindRiver company, is the most expensive and well supported Real-Time commercial product. It has been used for many years in many famous labratory to do some real-time needed experiments like human interactions, … It costs around 4000$ per license. In additions, WindRiver has a university program which can donate to your university for several licenses for 3 years, read more.


I am not familiar with QNX so just have a look at Wikipedia:

As a microkernel-based OS, QNX is based on the idea of running most of the OS in the form of a number of small tasks, known asservers. This differs from the more traditional monolithic kernel, in which the operating system is a single very large program composed of a huge number of “parts” with special abilities. In the case of QNX, the use of a microkernel allows users (developers) to turn off any functionality they do not require without having to change the OS itself; instead, those servers are simply not run.

The system is quite small, with earlier versions fitting on a single floppy disk.

QNX Neutrino (2001) has been ported to a number of platforms and now runs on practically any modern CPU that is used in the embedded market. This includes the PowerPC, x86 family, MIPS, SH-4 and the closely related family of ARM, StrongARM and XScale CPUs.

Those two QNX and VxWorks for commercial purposes and short-time development products, but, by contrast RTAI is the best choice for one who doesn’t want to spend big money, since it supports a lot of platforms. RTAI stands for RealTime Application Interface for Linux, which lets you write applications and runs it in real time (strict timing constraints) for your Linux distributions. In fact, RTAI is not a RealTime OS, it is just a patch for your Linux distributions since Linux OS itself doesn’t have realtime feature. Like Linux OS, RTAI is totally free and having a big community which can support you during developing your system.The famous and wellknown distributor is Roberto.

RTAI Homepage: https://www.rtai.org/

At this moment, RTAI supports following architectures:

• x86 (with and without FPU and TSC)
• x86_64
• PowerPC
• ARM (StrongARM; ARM7: clps711x-family, Cirrus Logic EP7xxx, CS89712, PXA25x)
• m68k (supporting both MMU and NOMMU cpus)

The latest version is RTAI 3.8 which was released in 02/16/2010.

How to get started ?

I am sure that you will get a lot of issues during playing with RTAI, so you can get supports from serveral sources:

• RTAI website: https://www.rtai.org/
• Install RTAI & Comedi & ScicosLab & QRtaiLab on Kubuntu Jaunty
• RTAI mailing list: https://mail.rtai.org/cgi-bin/mailman/listinfo/rtai

Note: You need to add RTAI certification in your web browser to view RTAI contents, otherwise you can’t access it.

Some useful articles out there:

• RTAI: Real-Time Application Interface | Linux Journal
• Real-Time Enhancements for Embedded Linux