Rasmus Friis Kjeldsens blog

Landmark observation model

2010-06-30T07:37:00.000-07:00

Using the fact that the height h of an observed landmark is constant for any angle of the landmark plane (for a constant distance d), and the width w variates with the angle, the observed angle of the landmark plane can be calculated as:
α = acos(w/h)

Landmark recognition

2010-06-11T06:44:00.000-07:00

I'm now working on implementing some of my master thesis I didn't have time to finish. Landmark recognition and distance to landmark, angle to landmark is now working, and only needs some tuning - the pixel classification is a bit too greedy.

RoboCup 2010

2010-05-24T12:40:00.000-07:00

So I came in as number 8 in the DTU RoboCup 2010, which I was quite happy about, given the amount of time I had to put in the project. Here is a video of Ridgy in the final round:

My robot Ridgy can pick up a golfball

2010-04-13T07:29:00.001-07:00

Ridgy can now pick up a golfball.

Acer Aspire One RAM mod

2010-03-24T14:09:00.000-07:00

I'm using an Acer Aspire One to control my robot. I'm coding using Eclipse, but the 512 MB RAM in the Aspire is too small, and it swaps. Swapping on the flash drive is very slow, so I finally took the courage to upgrade it to 1.5 GB, following this nice guide: http://tnkgrl.wordpress.com/2008/08/14/modding-the-acer-aspire-one-bluetooth/ .

It worked!

Inside the circuit box

2010-03-14T09:47:00.001-07:00

The circuit box is getting quite crowded with all these wires.

6 servos and a gate sensor

2010-03-14T09:39:00.000-07:00

While I had my circuit board disconnected to fix the tachometers I also added support for an extra servo motor, so the board can now control 6 servos. I've also added a gate sensor since I first blogged about the robot. The gate sensor is nothing more than a switch on a stick.

I need to shorten that USB wire from the camera...

Tachometer blues

2010-03-14T09:13:00.000-07:00

So my tachometers suddenly started acting weird. When on the edge between black and white, the tachometers counted up like crazy. I figured the Schmitt triggers on the input pens on the Atmega must be a little too sensitive. They have a hysteresis of only 0.25 volts @ a supply voltage of 5V, thats a bit in the low end. So I added a 4093 quad nand schmitt trigger IC (hysteresis 0.9V), and after a little confusion (forgot one single connection on the circuit board - that gave really odd results), the tachometers now run flawlessly.

The first video of my new robot

2010-02-07T05:41:00.000-08:00

My new robot can now follow a line pretty robust. Here is the first video of it:

This is what the robot "sees" when following the line:

The red and blue pixels marks the left and right edges of the line. I don't use that information yet and it is not tuned very well. The green pixels marks the center of the line. The yellow line is the result of the processing of the green pixels. This is the only information the robot uses to steer at the moment. It doesn't recognize intersections or forks on the line and doesn't even recognize that the line ends. More to come later...

A picture of the robot:

Acer Aspire One hosts file

2008-11-21T05:54:00.000-08:00

On the Acer Aspire One Linux (Linpus) version, the /etc/hosts file is restored to its original state on each restart. After much fustrating googling, I finally gave up and tried to locate where in the startup the file is restored. The causing script is /etc/rc.d/rc.5 - Modify this if you want to customize the hosts file.

Problems installing anjuta on Ubuntu 7.10 Gutsy Gibbon

2008-02-28T11:14:00.000-08:00

I had problems getting Anjuta installed on my Ubuntu 7.10 Gutsy Gibbon. Synaptic tried to install a version with 3 broken dependencies, but forcing the version to 2:2.2.0-1ubuntu2 did the trick:

sudo apt-get install anjuta=2:2.2.0-1ubuntu2 anjuta-common=2:2.2.0-1ubuntu2

Mandelbrot in LINQ to Objects

2007-11-29T23:53:00.000-08:00

Inspired by LukeH's blog, I wanted to write a Mandelbrot generator in LINQ to Objects, just to get to know LINQ. Here it is:

var pixelsQuery = from y in Enumerable.Range(0, h)
    let fy = (y - h / 2.0) / (h / 2.0)
    select from x in Enumerable.Range(0, w)
        let fx = (x - w / 2.0) / (w / 2.0)
        let start = new MD { X = fx, Y = fy }
        let mandel = (Func<md,>)((md, i) => (new MD {
            X = md.X * md.X - md.Y * md.Y + start.X,
            Y = 2 * md.X * md.Y + start.Y
        }))
        let z = Enumerable.Range(0, imax).Aggregate(start, mandel)
        select new { X = x, Y = y, C = z.X < 4 ? Color.Black : Color.Wheat };

New Gumstix Verdex blog

2007-08-16T03:24:00.000-07:00

I've started a new blog about my Gumstix Verdex experiences.

Anmeldelse af Sony DVD Recorder RDR-HX717

2006-06-25T08:01:00.000-07:00

Anmeldelse af Sony DVD Recorder RDR-HX717

Jeg skal lige indlede med at sige, at jeg ikke har prøvet andre harddiskoptagere,
så jeg har ikke noget sammenligningsgrundlag.

På plussiden er:

Den støjer minimalt, helt klart acceptabelt.
Time-shift eller pause af live tv virker perfekt.
Live-cache funktionen er rigtigt smart: Optageren "kigger med" når man ser tv over den,
så man på ethvert tidspunkt kan spole op til 6 timer tilbage, og tilmed gemme det sete
permanent.
De 2979 kr, som Føtex har solgt den til (20. juni 2006) er en god pris for en 160 GB
harddiskoptager.

På minussiden er:

Når optageren har været slukket helt (på stikkontakten), tager det hele 35 sekunder
før den er startet op, og den husker ikke tid og dato, som så skal indstilles.
I praksis kan man således ikke slukke for optageren om natten for at spare strøm.

Når optageren tændes fra standby, tager det 10 sekunder, før den viser et billede,
også for lang tid efter min mening.

Optageren bruger GuidePlus-systemet til at finde kanal- og programnavne. Det virker ikke
i Danmark, og den kan ikke finde programnavnene fra teksttv. Stort minus!

Optageren kan også vise JPG-billeder som slideshow, men det tager 10 sekunder at
indlæse hvert billede - grotesk langsomt!

I løbet af den første aften jeg havde optageren, gik den ned to gange - Genstart tager
35 sekunder.

Der medfølger hverken dansk eller engelsk manual, men dansk manual kan dog hentes på nettet her: dk-manual.

Showview-systemet virker ikke ordentligt, det giver forkerte optagetider.

Generelt er optageren for indviklet at bruge, fx. er det ca. dobbelt så hurtigt at lave en
manuel timeroptagelse på min 10 år gamle video, som på Sony-optageren.

Min anbefaling: Køb en anden harddiskoptager! Jeg vil prøve at få pengene
tilbage for den jeg købte.

Aarstiderne og opbevaring af bananer

2006-06-19T06:10:00.000-07:00

På Aarstidernes hjemmeside står der, at man ALDRIG må komme bananer i køleskabet. For det første må det da være ens egen sag, om man vil komme dem i køleskab. For det andet og meget vigtigere, er det ideelt at opbevare bananer i køleskabet. Man skal bare huske at komme dem i en lufttæt pose. Så bliver de ikke sorte, og de modnes kun meget langsomt. Ganske praktisk, hvis man lige har fået 10 modne bananer fx fra Aarstiderne og ikke har tænkt sig at spise dem alle lige dagen efter.

Hello world

2005-09-15T06:33:00.000-07:00

Hello World!