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.

AntOS v 0.2.4-alpha release

I have too many work in the last few months and don't have time to deal with some known bugs of AntOS until now. This v0.2.4-a release focuses on improvement and bugs fix

Project page: https://github.com/lxsang/antos
Demo: https://os.lxsang.me/
AntOSDK tutorial: https://blog.lxsang.me/r:id:20

Applications developed using AntOSDK can be found on this repository: https://github.com/lxsang/antosdk-apps. They can be used as example projects for AntOSDK

Change logs

  • Improve API code
  • Fix the menu UI not updating/refreshing bug. This bug affects some applications: MarketPlace, AntOSDK
  • Fix the fileview UI updating automatically when its window title changes. This bug affects following applications: NotePad, AntOSDK
  • Fix the setting bug in File and release new version
  • Fix bug on MarketPlace and release new version
  • Fix bug on NotePad and release new version
  • Fix bug on AntOSDK and release new version

WARNING: Due to some recent attacks on my server, the web terminal access is disabled for the user: demo. Someone tried to run a TOR relay on my server using that user, so i decided to disable the terminal access on the demo user. You can still login, but you can't use the shell

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!

Adding noise to odometry data published by the Gazebo simulator

I've had funny time playing around with the Gazebo simulator for autonomous robot exploration. One thing I've encountered is that the odometry data provided by Gazebo is so perfect that, sometime, makes the simulation less realistic. I used a Turtlebot model as robot model in my simulations. Googling around, i didn't find any solution of adding noise to the odometry data of this robot (using the URDF file). I then decided to develop a dedicated ROS node allowing me to add some random noise to the Gazebo's odometry data.

The robot motion model

First thing fist, we need to understand the robot motion model. There are many motion models, but in the scope of this article, we focus only on the odometry motion model. Often, odometry is obtained by integrating sensor reading from wheel encoders, it measures the relative motion of the robot between time \(t\) and \(t-1\) or \((t-1,t]\). In 2D environment, a robot pose is represented by a point \((x,y)\) and an orientation (rotation angle) \(\theta\), so the robot pose at the time \(t-1\) and \(t\) are denoted by:
$$p_{t-1}=(x_{t-1},y_{t-1},\theta_{t-1})$$
$$p_{t}=(x_t,y_t,\theta_t)$$

Setting up a software stack for autonomous mono robot exploration and mapping using ROS

Prerequisites

This setup is performed and documented on an Ubuntu system with the following software stack:

  • Ubuntu 16.04 LTS (may work on other distribution though)
  • ROS kinetic: if you don't have ROS pre-installed, please refer to this tutorial http://wiki.ros.org/kinetic/Installation/Ubuntu. I suggest to use the full desktop installation configuration, this will take a while (> 2 GB)
  • Gazebo for simulation (it is installed by default if you choose the full desktop installation when installing ROS)
  • GIT (sudo apt-get install git)
  • Catkin for package building (installed by default when installing ROS)

To follow this post, some basic knowledge on ROS is needed:

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.


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