Tag Archives: sdu

ARToolkit problems with Ubuntu 9.10

In our project we have the ARToolkit installed on several machines, and not all machines have problems with the V4L version of the toolkit, so you could try out the V4L version before resorting to the GStreamer version.

If you encounter the following error: “error: acquireing channel(0) info” it probably means you should configure the ARToolkit for GStreamer. Apparently this is due to some problems using V4L2 libraries, which is not supported by ARToolkit.
To do this you should re-run configure and make in the root of the ARToolkit to rebuild the toolkit. It is important to remember to clean the previous installation before reconfiguring. This can be done by running “make clean” in the root folder of the toolkit.
When configuring select option 5 “GStreamer” and choose the rest of the options that are appropriate for your system. After compilation you should be able to run the “simpleTest” demo.

If the default options does not work with the simpleTest example, it might be necessary to specify some options before running the example. Try running the following command to set options for ARVideo.

export ARTOOLKIT_CONFIG="v4l2src device=/dev/video0 use-fixed-fps=false ! ffmpegcolorspace ! capsfilter caps=video/x-raw-rgb,bpp=24 ! identity name=artoolkit ! fakesink"

Remember to change the device string to point to right camera source.

VPN forbindelse til SDU i Ubuntu

Det er muligt at forbinde til SDU’s netværk i Ubuntu via VPN. Denne guide er skrevet med henblik pÃ¥ brug af Ubuntu 8.04 og Gnome.

Der er nogle generelle oplysninger pÃ¥ SDU’s hjemmeside inkl. en installationsguide og en link til en Cisco klient der kan downloades. Det ser dog ikke rigtig ud til at der er nogen klient at downloade, men klienten skal heller ikke bruges her. I installationsguiden stÃ¥r der at man skal bruge et gruppenavn og gruppepassword, og at det kan fÃ¥es ved henvendelse i Helpdesken. Jeg har modtaget mit direkte fra mit institut, sÃ¥ jeg har ikke prøvet helpdesken, men man skal bruge begge dele for at guiden virker.

I Ubuntu skal man have installeret pakkerne “network-manager-vpnc” og “vpnc”.
sudo apt-get install vpnc network-manager-vpnc
Derefter er det nødvendig at genstarte network-manager og den nemmeste løsning er simpelthen at genstarte computeren.

Nu kan man konfigurere VPN forbindelsen ved at venstre-klikke pÃ¥ NetworkManager ikonet i statusbaren og vælge “VPN-forbindelse” og “konfigurer VPN”.

  1. Vælg “Tilføj” og følg skærmene igennem.
  2. Vælg Cisco VPN-klient.
  3. Udfyld “Required” pÃ¥ det første faneblad. Mit gruppenavn er tekvpn, men det er afhængigt af hvilket fakultet man er tilknyttet.
  4. Under “Optional” udfyld dit brugernavn (inkl. domæne pÃ¥ formen: “domæne\brugernavn”) og vælg “Brug domæne til brugerverification”. Mit domæne er “tek” men det er naturligvis afhændigt af fakultetstilknytning.
  5. Sidst men ikke mindst skal man vælge “Enable weak single DES encryption”.

SÃ¥ er det muligt at logge ind ved igen at venste-klikke pÃ¥ NetworkManager ikonet i statusbaren og vælge “VPN-forbindelse” og klikke pÃ¥ den nyoprettede VPN forbindelse og udfylde gruppepasswordet og det almindelige password man bruger til at logge pÃ¥ domænet.

Det er OK at bemærke det ironiske i at man skal sætte flueben i “Enable weak single DES encryption” nÃ¥r der pÃ¥ SDU’s oplysningsside stÃ¥r “Benytter 3DES kryptering (168bit) og betragtes som den mest sikre protokol”…

Lego Mindstorms Crocodile Robot

The objective of the AM36 2007 course was to build an animal-like robot, using Lego Mindstorms NXT, for the RobotsAtPlay Festival 2007. Specific requirements included: Not using wheels for propulsion, some form of interactivity available, and ready in two weeks.

Designing the Robot

The following drawings were made for the initial design of the robot.The head and body were implemented in the basic style sketched here,while several changes were made to the design of the legs. Additionally, some of the planned sensors were not used, and the activities linked to those sensors not implemented.


Head design and a first draft of possible design for legs.


Body seen from top. Approximate proportions, and sensor placement.

The following sections are the design document containing the original plans for interaction, software, use of sensors etc.


The Lego Crocodile is an interactive Lego model, resembling in outlook and behaviour a real crocodile. The model is capable of moving around, either because of activity in its proximity, as well as by its own will. The model will in general remain passive, seeking to obtain a position in the sun, as other animals in the reptile family. Occasionally it will become active, either seeking a better position in the sun, or scavenging for food in its vicinity. The model can also be activated by other animals or humans entering its proximity. Depending on a number of things, including the interval since last eating, the crocodile will attempt to either engage the disturbance, or move to another position to resume sun bathing.


To make the robot interactive, the robot processes sensory input simulating sound, sight and touch. The robot will also have additional behaviour patterns, which are driven by a schedule. Finally, a remote controller, using Bluetooth, can activate several functions of the robot.

Activity patterns

The robot will actively try to place it self in a lighted area, seeking sunlight as other animals in the reptile family. It will stay in the light for a period of time, unless disturbed, and occasionally seek out a better spot. The robot can be “stirred” by entering into its field of vision, and will then react according to several variables. Either moving towards the object in its vision, or trying to back away and finding a new place to rest. The robot will send out sounds, warning intruders of its mood. As well as vision, the robot will use hearing to react to objects coming close to it. If stirred by its hearing, the robot will try to move around, seeking to get the disturbance into its field of vision. The robot will seek out food thrown to it, if it’s hungry, and try to consume the food. Continue reading