Friday, November 7, 2008

Robot Lego NTX Mindstrom

The Lego Mindstorms NXT system is a computing brick featuring a 32-bit autonomous Lego processor that can be programmed via PC or Mac (which is a first). The programs designed on the computer can then be transferred to the NXT Intelligent Brick through a high speed USB 2.0 cable or by using the brand new Bluetooth wireless feature. This Bluetooth technology makes it possible to control the NXT Brick wirelessly by means of a PDA, cell phone, laptop and more.

Not only has the Intelligent Brick been redesigned but the sensors and motors have been revamped as well. Here is a quick list of what has been changed and added:
  • 3 interactive servo motors feature inbuilt rotation sensors to align speed for precise control
  • New ultrasonic sensor makes robots "“see" by responding to movement
  • New sound sensor enables robots to react to sound commands, including sound pattern and tone recognition
  • Improved light sensor detects different colors and light intensity
  • Improved touch sensor reacts to touch or release and allows robots to feel
  • 519 hand-selected, stylized elements from the LEGO TECHNIC® building system ensure robot creations will be sturdy and durable while also looking authentic
  • Opportunities for physical programming of robots and interaction with robots during programming
  • 18 building challenges with clear, step-by-step instructions help acclimate users to the new system to create robots ranging from humanoids and machinery to animals and vehicles
  • Digital wire interface allows for third-party developments

What is inside the NTX Brick ? The full hardware specs as released by LEGO are as follows:
  • Main processor: Atmel® 32-bit ARM® processor, AT91SAM7S256
    • - 256 KB FLASH
    • - 64 KB RAM
    • - 48 MHz
  • Co-processor: Atmel® 8-bit AVR processor, ATmega48
    • - 4 KB FLASH
    • - 512 Byte RAM
    • - 8 MHz
  • Bluetooth wireless communication CSR BlueCoreTM 4 v2.0 +EDR System
    • - Supporting the Serial Port Profile (SPP)
    • - Internal 47 KByte RAM
    • - External 8 MBit FLASH
    • - 26 MHz
  • USB 2.0 communication Full speed port (12 Mbit/s)
  • 4 input ports 6-wire interface supporting both digital and analog interface
    • - 1 high speed port, IEC 61158 Type 4/EN 50170 compliant
  • 3 output ports 6-wire interface supporting input from encoders
  • Display 100 x 64 pixel LCD black & white graphical display
    • - View area: 26 X 40.6 mm
  • Loudspeaker Sound output channel with 8-bit resolution
    • - Supporting a sample rate of 2-16 KHz
  • 4 button user-interface Rubber buttons
  • Power source 6 AA batteries
    • - Alkaline batteries are recommended
    • - Rechargeable Lithium-Ion battery 1400 mAH is available
  • Connector 6-wire industry-standard connector, RJ12 Right side adjustment
Lego Mindstorms NXT is definitely quite an interesting and thought inspiring “toy”… if it can even be called that. And to top it off, there are several additions to this base set coming down the pipe in the next few months that’ll surely add to the complexity that can be derived from it. So, It will be make you fun, therefore you learn about robotics system instanly.

Website Source :
  1. Official site LEGO
  2. Project Engineering with Mindstrom
  3. Matlab Colaboration with NTX
  4. Relation Labview and Lego

Monday, October 6, 2008

State of Art Shape from Polarization

A thorough description of polarization of electromagnetic waves is given by Wolf and Born (1959). It is start from assume the light is a transverse electromagnetic wave. Wolf described a polarisation state of the electric field.

The use of polarisation in the computer vision literature begin at work by Koshikawa (1979). In his research, koshikawa has used only the linear polarisation state. Since it is sufficient for most applications where unpolarised light is reflected by a surface (Wolff and Boult 1991).

Wolff (1991) assumes that surfaces are lit with unpolarised light, and uses a Fresnel reflectance model which predicts the polarisation state of light reflected from dielectric and metallic surfaces. This model is based on the Fresnel reflection coefficients F⊥, which specifies the attenuation of the light polarised perpendicular to the plane of reflection, and F||, which defines the attenuation of light polarised parallel to the plane of reflection. If these coefficients differ from each other, reflection of unpolarised light results in polarised reflected light. The values of the coefficients depend on the type of material (dielectric or conductive), its index of refraction, the type of reflection (diffuse or specular) and the angle of incidence or emittance (Wolff 1991). For specular reflection of smooth, dielectric surfaces, F⊥ >= F||, resulting in linear polarisation perpendicular to the plane of reflection. The degree of polarisation depends on the incidence angle θi, and reaches 1 at the Brewster angle, arctan(n), where n is the index of refraction, and approaches 0 at θi = 0 and θi = 90◦. Diffuse, or body reflection results is largely unpolarised light (Wolff and Boult 1991), except for large large viewing angles θe. For this case, the polarisation direction is parallel to the emittance plane defined by the surface normal vector ~n and the viewing vector ~v.

The dependencies of the Fresnel coefficients on the material type can be used for material classification by computing the ratio of the Fresnel coefficients of specular reflections. Wolff (1991) proposed further applications of the Fresnel reflectance model including classifications of edges according to their origin (occluding boundary, specularities, albedo and shadow edges), separation of diffuse and specular reflectance components, and the estimation of surface normals using specular reflections on dielectric surfaces.

Since the polarisation state of reflected light is a function of the orientation of the surface, polarisation measurements can be used for estimation of surface orientation. For specular reflection from smooth dielectric surfaces, the polarisation angle ϑ defines a plane in which the surface normal is located. Together with the specular angle of incidence, the surface normal can be determined. Estimation of the specular angle however requires knowledge index of refraction and is subject to a two way ambiguity, except at the Brewster angle, where the degree of polarisation reaches 1 (Wolff 1991).

In other work by Miyazaki et al (2003) a spherical surface normal distribution is assumed and the 3D surface shape and intensity reflectance properties are estimated from a single image lit with multiple light sources.

Miyazaki et al. (2004) propose a related method for reconstruction of transparent objects, where the object is illuminated with light from all directions, producing specular reflection over the whole surface. The two way ambiguity is resolved by using a second image with slightly rotated object.

A Fresnel reflectance model with complex index of refraction has been used by Morel et al. (2005) for the reconstruction of very smooth, mirror like metallic surfaces. In a later publication (Morel et al. 2006), the specular angle ambiguity is resolved by varying the illumination.

Note that all surface estimation algorithms above are limited to reconstruction of smooth, dielectric and metallic surfaces without interreflections. Since the polarisation of the diffuse reflectance component of dielectrics is very low, most approaches assume specular reflections, and thus require a uniform, spherical illumination.

Tuesday, March 4, 2008

Polarization Vision

Polarization analysis has already been applied to diverse problems in computer vision. Koshikawa (1979), Wolff (1987) and Koshikawa and Shirai (1987) recognised the potential of ellipsometric techniques to determine the orientation of dielectric surfaces, effectively a “shape from X” method. For example, Koshikawa and Shirai used several, circularly polarized light sources, causing specular reflections on the object surface so that the normals could be extracted at these points if the material properties were known. Using a facetted approximation, this was used to match scene against
known model facets to recognise and constrain the pose of the object (Koshikawa and Shirai, 1987). Jones and Fairney (1989) performed a similar task but using unpolarized, rather than circularly polarized light as the illumination source.

For precise instrumentation we have method yielded good pose estimates. These methods require very precise knowledge of the polarization state of both the incident and the reflected light, the latter in particular requiring accurate measurement of reflected intensity at different settings of the polarizing optics within the receiver. Knowledge of the material refractive index is also required. As Wolff remarked subsequently (Wolff, 1990), there are more effective methods for acquiring depth data.
Muller (1996) and others (Fryer and Miller, 1991; Mersch, 1984) have used polarization to distinguish
specular from diffuse reflections in a computer vision system. The crucial assumption in their work is that the specular reflections are unwanted and have higher intensity than the diffuse reflections. Muller used three orientations of a polarization filter to acquire three images, from which the specular and diffuse components were calculated using the Fresnel equations. Further simplifying assumptions about the scene and optical geometry and the material constants can eliminate the necessity to acquire three images; a single image acquired with a linear polarizer is sufficient. Nayar and coworkers (Nayar et al., 1997) observed that by considering colour and polarization simultaneously, more robust results could be achieved to discriminate between specular and diffuse reflections from a dielectric. This follows earlier work on the labelling of edges by examining the polarization of the light reflected from
adjacent dielectric surfaces (Boult and Wolff, 1991) and an even earlier description on the use of polarization to distinguish specular from diffuse reflection (Wolff, 1989). More recently, Chen and Wolff (1998) have considered that metal-dielectric discrimination is possible because metals and dielectrics differ in the phase change of polarized light on reflection.

source : Improving Depth Image Acquisition Using Polarized Light, A.M. WALLACE, B. LIANG, E. TRUCCO AND J. CLARK, 1997

Thursday, March 8, 2007

In-Car Computing

In-Car computing takes in-vehicle entertainment to the next level. Now you are no longer stuck with a proprietary black box that is not upgradeable and only capable of what it is designed for. You can use PC Vehicle Packet for DVD playback, Digital Movie Jukebox (upload your favorite DVD movies into the system's hard drive), MP3 Music Jukebox (say goodbye to the CD-Changer that you haven't touched in months), Multi-User Gaming* (allow your passenger to play multi-user games with his/her friends in another car though Wifi), GPS Navigation System* (select from 2-D, 3-D, or Bird's Eyes' View), Satellite radio* (listen to your favorite commercial free stations), Wireless Internet* (Need instant movie time, stock quotes, or sports scores?), and much more!

This is Example to make your car up to sky :

Audio / Video
  1. Satellite Radio Controls - Enjoy over more channels of digital audio, mostly commercial-free. Requires an active subscription to vendor Satellite Radio services.
  2. Digital Media Player - Play digital audio and video from your home pc or organizer in your vehicle. Create playlists that will last you from Cancun to Quebec!
  3. Integrated DVD Player - That movie for your kids, the instructional video for your employees, or simply that action flick you missed now available to you on the go.

  • Vehicle Control - The optional EIM module allows on-screen control of up to 6 user-assignable vehicle features. ( Professional installation recommended )

  • Web Browser - An full-featured web browser with integrated favorites organizer, dial up manager, and pop-up blocker!


  • Application Launcher - Without any programming knowledge and just a few clicks you can instantly create buttons to your own applications.

Other Standard features

  • Day / Night Mode - Automatically changes color schemes and graphics for high-contrast daytime and low-glare night modes with headlight controls.*
  • Automatic Safety Locking - Automatically locks doors when driving and after dropping off a passenger.*
  • Large Format Calculator - From Tolls and Miles Per Gallon to mortgage rates calculate on the go!
  • On-Screen Keyboard - For easy data entry. System Volume Controls

Your office in your dashboard

Ever wanted complete access to your office contacts, and schedules when you're out of the office? This is the package for you....your mobile office on the go, keeping pace with your business lifestyle. A single environment providing you with integrated organizer and scheduler with mobile device sync ability, a mobile media center incorporating features normally expected from a home system, and web connectivity. Imagine your office in your dashboard!

  • Turn-by-turn directions with voice prompts. A clear voice will give you forewarning of the next series of moves required to get you to your destination.
  • Points-of-interest (POI). Need gas? Need an ATM? Your local iMobile dealer? No Problem! iMobile will instantly highlight nearby Point-of-Interest and guide you there seamlessly.
  • Dead reckoning capabilities for unparalleled accuracy. This technology allows the system to continue to deliver guidance even if you lose GPS reception in tunnels or urban areas (FUTURE RELEASE).
  • The Traffic Message Channel (TMC) for early warnings to reroute around traffic jams, accidents and construction sites(FUTURE RELEASE).
  • Fully-Integrated Scheduler and Address Book. Yes, that's right with a click of a button all your personal and business contacts become instant Points-of-Interest on the map so you can navigate to them with just one-click!
  • Scheduled reminders and event alarms. Forget to walk the dog? Pick up the kids? Not with our system. iMobile Executive will keep you inline by reminding you beforehand. Just be careful....this may change your reputation!
  • Synchronizes with Palms and Pocket PC. Dock it - Sync it. It's that easy to import all your contacts, memos, calendar events right from your PDA / organizer to your system.
source : xenarc technologies