reg:exp

Goodbye, Bay Meadows.

Bay Meadows, the storied horse racing track a few blocks from our place shut its doors for good last week. A brainchild of Bill Kyne, it first opened in 1934, when the rest of the Peninsula was still filled with farms and orchards. Smack between El Camino and Highway, it's now a prime piece of real estate and the track will quickly be replaced with condos and other standard high-density fare.

This weekend, Bay Meadows auctioned off all of their assets - chairs, track markers, signs, paintings, even ceiling tiles. Tania and I bought two great photographs as a memory to the place:

A photo of Bill Kyne with Abe Kemp, from some time in the 1930s or 1940s; and an awesome, large-format action shot of a 1974 steeple chase race:

First Mechanical Turk Experiment just Shipped!

Amazing but Tr...

By Folks on the Internet

Book Preview

I just finished editing my first MTurk book "Amazing but True Cat Stories" by Folks on the Internet. Submitters were paid to send stories and images about their cats. I selected, edited and laid out the stories in a Blurb book.

Update: The book now has its own page at projects/catbook

Making lemonade...

Keep your software with your hardware!

After building a number of physical computing projects on a number of different computers over the years, I frequently run into the following problems:
I pull an old project off the shelf that is still running and I want to modify it. However, I have absolutely no idea which computer and which folder my project files are on. I likely don't even use the computer anymore. Even worse, sometimes I pull an Arduino board out of a completed prototype because I don't have another board on hand. After pulling out the board and reprogramming, I now have a broken prototype with no easy way to get it back up and running again.

The basic idea to address this problem is to physically keep the entire project source files with the project at all times. My simple, ham-handed solution is to add both a USB flash drive and a USB hub to the Arduino hardware. You connect both the flash drive and the Arduino to the hub, and then connect the hub to the computer. Result: you can still shuttle data back and forth between the Arduino and the computer, but you also have a file system to store your project files.

Artists and students don't have a lot of money - so what's the cheapest way to implement this idea?

At my local Fry's, the answer is $7.98. That gets you a 128MB flash drive on closeout and a four-port USB 1.1 hub. Plug everything together et voila:

This first solution is clearly a bit unwieldy.

Above, I just took the PCBs for flash drive and hub out of their cases and zip-tied everything together. This is NOT functional, but closer to what we want to end up with. So off to the lab to make this smaller version work. To keep cabling under control, solder the flash drive directly to a port of the hub, and then solder another short cable with a USB B plug to a second port, to connect to the Arduino. This way, you don't have to solder to the Arduino itself and can connect and disconnect the entire storage+hub part.

Above is the final (functional) prototype - the added bulk is minimal, altough the board is no longer on stable footing. Here's another shot from a different angle:

That leaves one step: to have the Arduino environment save it's project files to the USB stick automatically. This is accomplished by opening the Arduino software and changing the sketchbook location under Preferences.

As an extension, you can imagine storing your entire Arduino development environment on the Flash drive as well. In this case, you'll have to choose at least a 256MB stick (1GB sells for $10 right now) and a USB2.0 Hub ($10 as well).
If the ugliness of the prototype is a concern, one could design a shield that houses both a mini breadboard, a USB hub chip+circuitry, and a USB plug where you supply your own flash drive.

Thanks to Sean Follmer for helping with construction and photography.

Introducing the alter ego..

I met Craig Schwartz at Foo camp who runs a fabulous site called toonlet that lets you create comic strips in a snap. Here's my alter ego:

Talk at MX

I'm back from 3 months at MSR in Seattle and am catching up on some long overdue posts. In April, I spoke at the MX ("managing experience design") conference in San
Francisco. One of the details that stuck with me was their use of realtime
graphic recording in the back of the room and I thought I'd share the
two drawings that were created during my talk:

All of these images are also in the Graphic Guide to MX 2008 (large pdf).

There's also an interview with me online at Boxes and Arrows.

Input Devices: What You Do != What Is Sensed

Together with Sean Follmer and Pat Hanrahan at Stanford I've been thinking about ways to describe and model the design space of input devices.

One important point from our discussions is that the action the user of an input device performs is often very different from what is actually sensed by the device. This difference is rarely discussed in HCI literature, yet the people who design input devices are acutely aware of it. Toy designers for example are experts in exploiting it. Since toy development is driven by cost, almost all toys will only contain the most elementary I/O components: buttons and LEDs.

Take the game "Bop It" for example: It's a variation on "Simon Says" in which you have to perform different actions ("bop it, spin it, twist it, flick it, pull it") on cue.

Yet inside Bop It, there are no potentiometers, sliders, encoders or flex sensors - everything is done with simple momentary switches and some ingenious mechanisms.

For example, in the "spin it" action the user spins a plastic gear. Inside, the gear has a recessed groove that acts as a cam. A plastic arm follows the groove while pivoting around a point at the center of the arm. When the groove moves away from the center of the gear, the arm pushes a momentary switch on a circuit board:

Low-cost IKEA light tent

This weekend I built a light tent to take better glamour shots of Tania's selfmade plush toys and some of my past projects. Lots of plans for light boxes float around: Instructables has light box projects using cardboard boxes and plastic buckets; the Make Blog links to Bill Huber's PVC light box, made out of PVC pipe and a bed sheet. As I was getting ready to drive to the local hardware store to get supplies for the PVC frame, I realized that you can probably get a sturdy metal frame from IKEA for the same price as some sections of PVC pipe. Hurray for economies of scale.

Here then is the low cost IKEA light tent:

Items from Ikea:
1 - ANTONIUS laundry bag frame. $7
1 - SOVA twin bedsheet. $3
2 - FAS clip-on lamps w/ E26 socket. $10 ea.
2 - SPARSAM Bulbs (75W equiv., 15W energy saver, 950 lumens). $4 ea.

Items from any office store:
Box of large binder clips. $3
22x28" posterboard, various colors. $4

Ikea parts:

(sheets didn't fit, and there's and extra extension cord in the picture)

Assembly is trivial: put the laundry bag frame together; drape the sheet over it; secure the sides of the sheet to the frame with large binder clips; slide a poster board into frame; attach it on the upper back cross bar with another binder clip from the outside. Clip the Fas lights onto the frame (they only like to stay put on the wider side of the frame profile). Done.

One downside to this tent setup is that you will have copious amounts of extra fabric spilling over the desk and floor below. To improve on the design, Tania sewed a custom-fit cover from a second SOVA flat sheet that slides over the frame - this is a good deal of extra work, but the result is much cleaner looking:

The most expensive items, and the ones I'm least satisfied with so far, are the lights. A wider reflector, the option of using brighter bulbs, and more flexible clipping mechanisms would be nice. I toyed with the idea of using adjustable arm desk lamps (think Pixar's Luxo), but those would have taken up too much space on the table.

Here are some test shots:

Track archive finally online

I finally got around to upload MP3 files of most of my electronic music tracks from 1995 through 2004 to bjoern.org/music. All vinyl/cd/netlabel releases from the Tuning Spork years are cataloged and you can also find older, unreleased material dating back to my first four-channel experiments with ScreamTracker on a GUS soundcard with 512kB of sample RAM.

The Year in Books

Because of my qualifying exams, I didn't get to read much during the first half of the year. Here are the books that left an impression on me from the second half:

English: for some reason or other, these are mostly older books that I discovered in bookstores around the country or through recommendations from friends.
* D. Price - "How to make a journal of your life" (10 Speed Press)
* Gay and Laney Salisbury - "The Cruelest Miles" (Norton)
* Geoff Dyer - "Yoga for People Who Can't Be Bothered To Do It" (Vintage)
* David Brooks - "Bobos in Paradise" (Simon and Schuster) (recommended by Jaime - funny)
* Bill Buxton - "Sketching User Experiences" (Morgan Kaufmann)
* Bill Moggridge - "Designing Interactions" (MIT Press)

German:
* Heinrich Steinfest - "Die Feine Nase der Lilli Steinbeck" (Piper)
* Martin Suter - "Der Teufel von Mailand"
* Jakob Hein - "Herr Jensen steigt aus" (Piper)
* Christoph Hein - "In seiner fr�hen Kindheit ein Garten" (Suhrkamp)

You can also take a look at the full list.

The Year in Music

Here is my list of most-listened to albums 2007. Most of these are new releases, although there are a few items that I just had not found before (e.g., the great Luaka Bop back catalog). As in previous years, almost all of these come from eMusic where I've also created a matching playlist.

* Oh No - Dr. No's Oxperiment
* Heliocentrics - Heliocentrics
* New Pornographers - Challengers
* Deerhoof - Friend Opportunity
* Matthew Herbert - Score
* Lemon Jelly - '64-'95
* V.A. - Cuisine Non-Stop (Luaka Bop)
* V.A. - Beleza Tropical Brazil Classics 1 (Luaka Bop)
* Darko Rundek And Cargo Orchestra - Ruke
* Peder - And He Just Pointed to the Sky
* The Innocence Mission - We Walked in Song
* Elliott Smith - New Moon
* Explosions in the Sky - All of a Sudden I Miss Everyone
* Spoon - Ga Ga Ga Ga Ga
* Okkervil River - The Stage Names
* Ellen Alien & Apparat - Orchestra of Bubbles
* Apparat - Walls
* Parts & Labor - Mapmaker
* Max Richter - Songs from before
* Andrew Bird - Armchair Apocrypha
* V.A. - Stones Throw: 10 years - Stones Throw Mix
* Edit - Certified Air Raid Material (from Vladlen)
* Cansei De Ser Sexy - Cansei De Ser Sexy (from Scott)
* M.I.A. - Kala (from Scott)

CHI2007 - Talks I saw

Monday

Momento: Support for Situated Ubicomp Experimentation
(Carter, Mankoff, Heer)

Toolkit Support for Developing and Deploying Sensor-Based Statistical Models of Human Stiuations
(Fogarty, Hudson)

Authoring Sensor-Based Interactions by Demonstration with Direct Manipulation and Pattern Recognition
(Hartmann, Abdulla, Mittal, Klemmer)

Tuesday
Aligning development Tools with the Way Programmers Think About Code Changes
(Boshernitsan, Graham, Hearst)

Task and Social Visualization in Soaftware Development: Evaluation of a Prototype (Ellis, Wahid, Danis, Kellogg)

Building Upon Everyday Play
(Zhang, Hartmann)

Sustainable Interaction Design
(Blevis)

The Three Paradigms of HCI (Harrison, Tatar, Sengers)

SIG: End User Software Engineering

Wednesday
Koala: Capture, Share, Automate, Personalize Business Processes on the Web
(Little, Lau, Cypher, Lin, Haber, Kandogan)

iStuff Mobile
(Ballagas, Memon, Reiners, Borchers)

Social Dynamics of Early Stage Co-Design in Developing Regions
(Ramachandran, Kam, Chiu, Canny, Frankel)

Thursday
FASTDash: A Visual Dashboard for Fostering Awareness in Software Teams
(Biehl, Czerwinski, Smith, Robertson)

Making Mashups with Marmite: Towards End-User Programming for the Web
(Wong, Hong)

The I in CHI - Interactive Session
(Holmquist, Igoe)

New Shield Connects Phidgets Sensors to Arduino Board

I just received my first Arduino Shield PCB design in the mail from Advanced Circuits. We have lots of Phidgets sensors lying around in the lab; they may be a bit pricey, but their plug-and-play model is sure handy when you're in a hurry. This PCB makes it easy to connect these sensors to the Arduino platform. The board has six Phidgets (aka 3 pin Molex C-GRID) connectors which are routed directly to the Arduino's A2D ports. It also breaks out 8 bits of digital IO to .1" headers and provides the all-important reset switch and status LED.

PCB design - Eagle files (based on Tom Igoe's Protoshield):

Parts:

You will need 6 Molex connectors. They are about $1 each when bought in small quantities from Digikey, and are available either with Gold or Tin leads (Tin is cheaper):
- Molex 70553-0002 3 Position Right-Angle PCB Connector (Gold)
  Digikey# WM4901-ND
- Molex 70553-0037 3 Position Right-Angle PCB Connector (Tin)
  Digikey# WM 4925-ND
Resistors: 2x10k (for reset circuit) + 1x330 (for LED)
Reset switch: standard 0.25" tactile pushbutton.
Jameco #153252.
Single row headers: buy a strip of 40 and cut shorter strips of 4 (power from Arduino), 6 (analog in to Arduino), 2x8 (digital IO to/from Arduino), 1x8 (digital IO header on shield).
Jameco #160882.
Double row headers: one strip of 8 doubles (16 contacts) to complete the digital IO header on the shield.
Jameco# 109568 (16 contacts); or 117197 (80 contacts - cut to size).
1 LED - I recommend a T1 size, but really, any standard LED should do.
Female header (this goes on the bottom of connector ICSP to get to reset function
Filtering capacitor, if needed

Note: this shield was designed for the original Arduino and does not use the 6-pin power+reset header the Diecimila has. I'll have to investigate whether there is enough space for the 6 pin header for the next iteration.

Testing, Testing: Wireless 3D Accelerometer

Received some Arduni Prototyping Shields from SparkFun a week ago and finally put one to use: This is a ugly, bulky prototype of a 3D wireless accelerometer, using Pascal Stang's ADXL V1.1 3D accelerometer board and SparkFun's BlueSMiRF bluetooth module.

Lessons learned:
* The BlueSMiRF header on the shield is NOT connected to the UART (D0, D1), but to pins D2, D3. I had to solder my own connector to use the Bluetooth module as a "wireless serial cable". Boo.
* When sending a lot of data (OSC messages at ~100Hz), the BlueSMiRF chokes and is not discoverable from the PC anymore. Putting in lots of delays helped, but made the sensor reporting rather sluggish. Should probably not send anything out until a secure serial connection is established in the first place - maybe use the free microswitch on the shield to start/stop sending?

Galvanic Skin Response Sensor

I just finished building a galvanic skin response (GSR) sensor for two students who want to use it for a gaming study. The sensor measures the varying resistance of human skin, which is suppsedly a proxy for engagement in a game. I guess we'll have to wait for the results of their study to see how well this works.

The sensor has two probes that you strap around two fingers; a black plastic Fry's box where all the electronics live; and a USB connection to send sensor data to a PC.

Since you don't want to send a lot of current through your body, the sensor circuit is built around an op amp (LMC6442 single supply rail-to-rail), based on the schematics published by Michael Sung and Vadim Gerasimov here. I didn't have a 100k pot handy so I approximated with 3x20k pots and a 10k fixed resistor in series. Built on one of the super handy One Pas prototype boards. Output here is an analog voltage in the 0-5V range. This output is hooked to to and ADC port of a small d.tools board, which in turn sends data to a PC, but you can substitute your favorite PC interface here easily (Arduino, Phidgets, ...). On the PC, I graph results in Exemplar.

The finger probes were inspired by the Lego GSR Sensor page. I tried three types of probes: 3/4" copper foil tape on velcro (too thick, green fingers); 1/4" aluminum foil tape on velcro (glue not conductive); thumbtacks on velcro (preferred solution)