Life-Size Katamari Lives

A long time ago, in a galaxy identical to this one, I wanted to make a life-sized Katamari, and use it to play Katamary Damacy on PS2. My friend Eric Skiff shot a video, and while it’s not quite a polished project, I decided it’s time to share it with the world.

My very technical schematic

My very technical schematic

It uses an optical mouse to track the ball. I gathered up some cheap PS2 controllers, ripped out the potentiometers on the analog sticks, and replaced it with a digital potentiometer and an arduino. The arduino takes signals from two PS/2 mice (one for each analog stick) and adjusts the potentiometer accordingly.

Ribbon cables soldered to where the joysticks used to be

Ribbon cables soldered to where the joysticks used to be

It’s the first circuit I’ve ever designed, so obviously it has a lot of room for improvement. The biggest one being that there are two separate power sources, one for the Arduino and one for the PS2. We’ve discussed lots of different ways to run the whole thing off the PS2’s power, but all of them require a little more studying on my part to fully understand. I started this project with almost no knowledge of physical computing. I got the “electricity is like a river” talk from my fellow Resistors, and a lot of pointers along the way.


Here’s the wiring schematic. I realize it doesn’t make a lot of sense. Basically the each mouse (one for each joystick) is wired up to the Arduino, and there’s a handy PS/2 library for Arduino which makes it easy to work with. It was also the first Arduino program I wrote after “make an LED blink.”

I used an AD5206 digital potentiometer chip, although the 5204 would work as you only need four channels (left x, left y, right x, right y). It’s a pretty simple circuit, and maybe when I have some time I’ll redo it to use an AVR and a single power source. It was a fun first electronics project.

Originally I wanted to use one of those giant yoga balls, to really get the scale. But it turns out those don’t roll very well on ball bearings. Luckily Adam had one of those mirror balls folks put in their gardens. Or at least I assume they do, no one I know has a big enough yard to put lawn ornaments in. While somewhat smaller and less impressive, it rolls much more easily.

This project wouldn’t have been vaguely possible without help from the fine folks at NYC Resistor, who very patiently explained things like “why do I need a pull up resistor?” Extra thanks to Eric who documented my work (something I forget to do) and Adam who helped me with EAGLE. Sadly I never did get around to properly etching a board for it (but I did have a lot of incorrectly etched boards).

You can find the music from the video at

Filed under: Katamari

88 thoughts on “Life-Size Katamari Lives

  1. spec says:

    Totally awesome and very clever. One question: Where did you find the big metal ball?

    1. Kellbot says:

      The ball started life as a “gazing ball.” The sort of thing hippies people put in their back yards. A friend of mine had one leftover from a previous project. They’re fairly inexpensive, but having them shipped can be expensive so your best bet is to find one locally at a tacky garden store.

  2. Awesome Kelly! Now get Chris to spring for a giant stainless steel sphere ( ). And mount that mouse so you can use both your hands.

  3. daphny says:

    this is WONDERFUL i have a friend who made a trackball to play sonic the hedgehog with and someone who made mike tysons jungle beat (punch out with donkey kongas) BUT THIS TAKES THE CAKE!

  4. Adam says:

    Great idea, can it handle turning left and right on the spot? Presumably you’d need 2 mouse sensors for that, set slightly apart. Inspired project, I may have to attempt one of these for myself.

    1. Kellbot says:

      It can indeed. The video doesn’t show it so well but there are two mice, set about 2″ apart from each other. The only Katamari move it can’t do is the quick flip. I have yet to come up with a robust way to integrate the push-in to the controller.

  5. Tony says:

    Nice work! I wanted to do something like this a few years ago but never got around to it. My thought at the time was using a bowling ball without holes drilled for a nice large, weighty feel. Very cool to see someone execute this idea though!

  6. Murph says:

    You can get a piezo speaker element (radioshack or anywhere) and use it as a sensor very easily w./ your arduino. It detects any bending (changes in pressure for example) Then you could detect if you ‘tapped’ the setup. That’d be a cool quick flip.

  7. obo says:

    Screams for force feedback. 😀 Great work!

  8. R says:

    I lorve you Kellbot

  9. This is really cool, i’m a huge fan of alternative forms of input for console and computer

  10. Conti says:

    I’d recommend patenting it or something >_> It’s really a neat idea and I would definitely buy it. I’m rubbish with electronics, so I can’t make one for myself.

    1. Kellbot says:

      I’m actually not that into the idea of patenting it, I’d much rather people made them for themselves than turn it into some sort of commercial venture.

  11. Thom says:

    Things like this make me so happy. So very, very happy.

  12. evan says:

    Very cool project.

  13. Psoridian says:

    You could mimic what some people do with DIY Dance Dance Revolution Pads. An inexpensive push switch is mounted placed in the base of a frame while a spring is mounted to the bottom of the foot pad with a shaft in the center to make up the distance.

  14. Nobyl says:

    very very cool. i wish id the knowhow to do this kind of thing. i just bought beautiful katamari for my xbox 360. /best

  15. Jay says:

    Hi ,

    Saw ur Katamari controller hack on .. its pretty interesting..

    And you are cute too .. !!! 🙂 .. Good to see cute chicks in Engineering.. robotic engineering .. 😀


  16. Martin_Keamy says:

    Very creative. I’m impressed. Bonus points for an awesome game like Katamari Damacy. 😀

  17. awesome concept, thanks for the wonderful use of the arduino

  18. JasonDJ says:

    Saw this posted up on reddit. Piezo element probably would be best, if you’ve ever seen the Japanese game Drummania (Rockband drums may be made the same way, haven’t opened one yet….) the drums are really just the piezo elements that Murph mentioned. Just buy one and crack open the case, the resulting sheet of metal would wire up and behave just like an SPST switch, except it detects pressure/vibration. I don’t know how sensitive they are though.

    Alternatively, I don’t know how sensitive those bearings that it’s mounted on are, or how much space and play there is, but you may be able to get a microswitch on each and wire them all up in parallel. That way a significant bonk on the top of the ball would push the bearing into the switch, tripping it.

    I’ve built a few ASC’s and custom controllers before including Pop’n Music and Taiko no Tatsujin and was really impressed with each of them.

    Best of luck.

  19. Lino says:

    OMG it’s perfect,you’re perfect, I think I’ve fallen in love with you 😀

  20. Techni says:

    I’d love to buy one of these off you.

    1. Kellbot says:

      I don’t have any plans to make them for sale, but encourage folks to try to make one of their own! It’s fun, and really not too difficult.

  21. Jeff says:

    I think I’m in love with Kellbot. Let’s get lunch sometime.

  22. Jon says:

    Great frickin idea.

  23. kaleb says:

    oh my god. i love this idea. now all we need to do is extrapolate it so you are inside the katamari running around to roll. that would be awsome. seriously good work and get it patented.

  24. Mondongo says:

    Great project! Katamari rulez 🙂

  25. A Fan says:

    Arduino + Katamari + Girl

    Marry me 😀

  26. Kyzumi says:

    Amazing! You are wonderful! I would love to use it

    I’m wondering if the mouse will eventually “attached” somewhere so that you can use both hands to roll

  27. Joe Bowers says:

    I love it! I don’t think Katamari should be played any other way.

  28. jefftheworld says:

    What’s the song in the video?

  29. Very nifty!

    Instead of gutting a PS2 controller, do you think it’d be possible to have the Arduino communicate directly with the PS2?

  30. JohnR says:

    Why dont you skip the D-Pot and talk the controllers serial commands directly from your micro?

  31. demizer says:

    I wish I was that cool.

  32. Shiam says:

    Love the idea, might even try to make one my self. I’m thinking though that something along the lines of an old ball mouse would make simpler movement detection in this case.

  33. biphenyl says:

    Ah, someone else with a game input hacking penchant. It turned out quite fabulous! And agreed, do one up yourselves folks — it’s good fun, and rewarding!

  34. John Park says:

    Fantastic work, I love this interface!! Maybe you can hack this one in Gothenburg:

  35. That is a great controller! Truly I have longed to roll katamari for myself for a long, long time.

    (Also, yes, you are rather cute.)

    Keep on trucking!

  36. Techni says:

    Well I have a medical condition which makes it impossible for me to solder. I was hoping to just buy the controller part. I could find a ball somewhere

  37. Mr Smooth says:

    MAd projekt !!! Really nice ! Now you must work on da speed katamari ball… when you play up and down on your paddle to accelerate the ball and throw it on levels. I suppose you can’t do this fonction at this time with the metal ball ?

    Definitively cool project !!

  38. woog says:

    Don’t take this as creepy or anything but could I just have a small sample of your DNA?

  39. Pantyhouse says:

    Girl, just amazing…

    Its the kind of stuff you saw in the morning and makes your day.

    Thanks for the idea… and hope to hear and watch more of your stuff.



  40. danny says:

    Someone please tell us what the song in the video is.

    1. Kellbot says:

      The music from the video can be found here:

  41. zushiba says:

    Sweet, I hope to marry a girl like that one day.

  42. Noah says:

    OMG OMG OMG. You rock entirely too hard. I wanna’ try it!

  43. Norway says:

    Just awesome, I’ve always found the controllers for Katamari kinda annoying.
    This is geniously created Kellbot

  44. Triften says:

    Which AD5204 did you use? 10k, 50k, or 100k? (Not that I’m trying to duplicate your work or anything… :D)

    @JasonDJ: I don’t think that’s how a piezo works. It generates voltage based on flexing. The Rockband drum works the same way so that they can detect how hard you strike (during fills and the freestyle drum mode). I modded one so I could use it with a real kickpedal and I had to make a circuit using a diode and a MOSFET to rectify the piezo output and make it equivalent to a SPST.

  45. Matthew says:

    Very, very creative. Saw this in an article on and had to come here just to say – great brains, great determination to make it happen, and lovely smile to top it off. I hope it spells a cool little revenue for you.

    But.. can you make us a holographic display to make this look even cooler? Imagine playing this like it was floating above your glass coffee table eh?

  46. kevin mcguigan says:

    i admire you. you are very talented and intelligent. i have been trying to learn how to write language for my arduino but i cant grasp it. any tips on how to make learning to write the programming language easier?

  47. JohnF says:

    Ok –
    just awsome

    I think I could get my wife to play if I had one fo these.
    Is there any way you could write up a document
    with step by step ‘idiot proof’ instructions on how to make one.
    Including the Arduino programming.

    I personally think you could contact Namco or Sony or someone
    about the possibility of selling your design and making a ‘Katamari Controller’

    Other games have their own game specific controllers – why not katamari.

    One question – in the game you can press both stick downward
    (L3 and R3) together to jump over the katamari and switch directions.
    Also some other featues that use the shoulder buttons. How is this handled in your design?
    I suppose a ‘Jump’ button that activates both L3+R3 could be wired in.

    Great work!

  48. Gabriel says:

    Greetings from Brazil, Kelly. I saw you sphere-controller here:

    And I found it very awesome! I’m sure it’s better than using that analogic controls. Also… sudddenly I’m willing to play Katamari again 😛

    Great work! [2]

  49. DeL337-- says:

    Hey sweet project, you should have gutted the mouse too and mounted the phototransistor and LED onto something under the big metal ball, cause it’d be a pain in the ass holding a mouse up to it all the time 🙂

  50. aGeek says:

    Thank you for this great idea!
    Really inspiring project. Optical mice can be used for tracking movement in a robotics project… I hope to try this asap.
    I’d have never thought of that.

    It’s as impressing as simple!

    Also, nice blog!

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