Older blog entries for cananian (starting at number 98)

SDR 0.7

Happy Thanksgiving! Here's SDR 0.7 to celebrate the holiday. Version 0.7 incorporates a number of dance engine refactorings completed shortly after the previous release promised them, as well as (more recently) a number of new call and concept definitions (and test cases) inspired by the C4 calls I am currently studying. I also updated Google App Engine and Google Web Toolkit to the latest versions for the web app, although jMonkeyEngine is still stuck at 2.0 — we might get an Android version of SDR if I manage to rebase to jMonkeyEngine 3.0 for the next release.

Breathing the square properly is still a challenge. Other square dance programs only treat starting and ending formations, but SDR has to consider all of the intermediate positions along the dancers' paths. This leads to some very unusual formations being breathed. As mentioned in the notes for the last release, SDR formulates breathing as a solution to a mixed integer linear programming problem—but there are still a few bugs lurking which cause the constraint solver to blow up from time to time (especially from columns, for some reason). Hopefully I'll be able to dig into this for the next release.

Syndicated 2012-11-22 19:29:56 from Dr. C. Scott Ananian

21 Oct 2012 (updated 11 Jan 2015 at 15:08 UTC) »

Reading Project Talk (and slides)

An unruly tag team of OLPC folks gave a long talk on the Literacy Project today for attendees at this year's OLPC-SF Community Summit. It was streamed live on Ustream: Part 1 (Matt Keller, Richard Smith), Part 2 (Richard Smith, Ed McNierney, C. Scott Ananian, Chris Ball, questions from the audience). We've posted the slides: Matt Keller, Richard Smith, C. Scott Ananian.

You can try out some of the apps mentioned in the talk. Nell's Balloons and Nell's Colors will run in any reasonably-recent Google Chrome or Mozilla Firefox browser. They will also run as a Firefox webapp on Android devices, using the latest Firefox nightly for Android. For deployment we use a slightly-tweaked build of Firefox (adding expanded webapp storage quotas and the ability to use plugins from inside webapps), and a custom plugin to hook up the Funf logging framework. Source code is available on github: nell-balloons; nell-colors. In addition, Chris Ball's "Matching" app for Android is available: apk; source.

Syndicated 2012-10-21 22:51:05 (Updated 2015-01-11 14:53:31) from Dr. C. Scott Ananian

The Importance of Sensing Distance

At IDC 2012 in June, Arnan Sipitakiat and Nusarin Nusen discussed how they are using Robo-Blocks—a turtle robot and “tangible Turtle Blocks”—to teach problem solving and debugging skills to 5- through 12-year-olds.

One of the things I learned from their presentation was that children had difficulty reasoning about relative angles. The Robo-Blocks robot does not have any distance feedback on its motors, so “the result of a program will change depending on the roughness of the surface and the battery level of the robot.” They worked around this issue by developing a protractor tool to guide the children's reasoning about the relationship between the (arbitrary) numbers entered and the amount the robot turned, but some kids still had difficulty. The researchers “often had to insist on trying the protractor” and “some children preferred to keep increasing the turn amount even if a small decrease would have fixed the problem” resulting in programs that had the robot making multiple complete rotations before setting off in the correct direction. The kids were also dissatisfied with polygon-drawing tasks (“turtle geometry”) because the inaccuracies of open-loop control of the robot means that the polygons often didn't close completely, and “[t]his small error turned out to be unacceptable to children.”

So I designed the XOrduino turtle robot from the start to have distance sensors so that it can do accurate turns with closed-loop control. Here's a little video showing how they work in the current (A1.5 / B1) revision of the board:

Some bonus pictures of the speed sensor on the workbench:

  • The robot on the workbench with probes.
    Speed sensor test setup
  • Signal from the motor speed sensor. 5ms/div .5v/div. Motor is running at full speed, unloaded. Two dips are seen: the larger is from a piece of white paper glued to the rim of the gear; the smaller is from a spot made with a white paint marker (the paint didn't stick very well). White-out worked much better (as shown in the video above).
    Oscilloscope trace
  • Oscilloscope settings
    Oscilloscope settings

Syndicated 2012-08-22 16:29:11 (Updated 2012-08-22 16:48:46) from Dr. C. Scott Ananian

XO Turtle Bot drives around

Here's a first look at an XOrduino Turtle bot driving around:

I've checked out all of the functionality on the A1.5 board except the step-up voltage regulator now. I'm optimistic the B1 boards (being made now in Taipei) will be clean.

It will be great when we've got lesson plans written up so kids can learn how to control the bot with Turtle Blocks, and play with the different possible behaviors. Instead of just bumping around ("like a Roomba, except it doesn't vaccuum" a friendly 6-year-old beta-tester told me), you can trace patterns you design, or use the Scratch Sensor Board sensors to make the robot "afraid of sound", "attracted to light", or add your own sensors and behaviors.

Syndicated 2012-08-18 05:13:16 from Dr. C. Scott Ananian

"Hello, World" from XOrduino/XO Stick

Here's a quick look at the next versions of the XOrduino and XO Stick boards. These were assembled from a small quantity of "pre-B1" boards I had made at BatchPCB.

I've uploaded some more pictures to the XOrduino album as well.

Here's a little table relating the board versions pictured with those I've previously discussed.

Build XOrduino XO Stick
A1 v4 v5
This video v6 v7
B1 v8 v14

B1 is "the next run" of boards, already released to the fab house but not yet in hand.

The big feature added to XOrduino after A1 was a motor driver, to allow using the XOrduino as a Turtle robot. The big feature added to XO Stick after A1 was the shield form factor, allowing it to ride piggy back on the XOrduino. This makes it easier to share a single turtle robot with a classroom: there may be only one XOrduino robot base, but each student can have their own low-cost XO Stick "brains". They can take turns snapping their brains on top of the base to drive it.

I haven't finished testing all the functionality of these new boards yet, but it looks like I haven't made any major mistakes! Help still wanted with software, documentation, etc; send email to xorduino@gmail.com if you're interested.

Syndicated 2012-08-15 20:34:02 from Dr. C. Scott Ananian

XO Bot joins the XOrduino and XO Stick

Free things first: I've got parts for 20 copies of the "Mk I" XOrduino and XO Stick. I'm mailing them out for free (!) in exchange for your development help. Send me an email at xorduino@gmail.com describing what you'd like to do with the XOrduino/XO Stick, and your full mailing address. Best 20 or so get kits.

XOrduino A1

Here are some of the projects which you might be able to help with:

  • Assemble an XOrduino / XO stick with an 8-12 year old and document the process. What parts were tricky to solder? Where did polarity matter? How much of the function of the different devices did you find worth explaining? Photos or video of children assembling the device would be great for future publicity, with their permission. (We're not crazy: kids can repair XOs and solder.)
  • Test different configurations of the boards. What are the fewest components necessary for a functional XO Stick? What capacitors are really needed? What's the smallest number of components needed to get the arduino IDE to talk to the XOrduino? Then add the components for the Scratch Sensor Board functionality, and test that with this Arduino sketch (some minor porting required). Try out whatever Arduino shields/old Arduino code you have lying around, and see if there are any gotchas there. Document it all, take photos and video, let me know about bugs and pitfalls.
  • Write some killer education apps! These boards are meant specifically for teaching kids—take the Turtle Art with Sensors ideas as examples, and write up some lessons to teach science. Or take inspiration from the old school "fun with electronics" kits from Radio Shack and recreate some of the popular standbys: a burglar alarm for kids' tree fort, a light-sensitive alarm they can hide in their sibling's drawer, etc. Or a document how to program a robot (more on the robot below) with simple emergent behaviors—avoiding walls, turning toward light, fleeing loud sounds, etc. The Cubelets examples may give you ideas. Take photos and video.
  • Arduino support for the XO Stick. There are a number of projects which add support for the ATtiny85 and friends to the Arduino IDE (for example, this one). Ideally we'd like to make the XO Stick as Arduino-compatible as possible, so we can reuse the excellent Arduino IDE, etc. This involves (a) porting an arduino-compatible bootloader (like usbAspLoader-tiny), as well as (b) porting the Arduino libraries to match the pinout/peripherals of the ATtiny85 and ATtiny861 (this page is a good start).
  • Program an XO Stick from an XOrduino and vice versa. Ideally we'd like to bootstrap the initial chip programming, so that one programmed XOrduino (or XO Stick) can be used to put the initial bootloaders on the others. For technical reasons the XO Stick is probably best as a "clone tool": without interacting with the USB bus it would just copy its internal memory to another XO Stick. The XOrduino is a little easier, just a matter of adapting the existing Arduino sketches and documentation.
  • Debrick an XO from the XO Stick. The XO Stick can talk to the EC programming bus to recover a bricked XO; it can probably also reprogram OpenFirmware. We need to write a bit of code to make it pain-free and document the process. This would make the XO Stick a useful repair accessory for XO deployments.
  • Scratch/Turtle Blocks support for the XOrduino and/or XO turtle bot (see below).

Here's the exciting part two: I'm already working on the XOrduino and XO Stick "Mk II". The latest schematics/boards are in github (xostick, xorduino). The kits I'll be sending out this week correspond to the "A1" tag in those repositories; the "Mk II" revision is on the master branch.

The XO Stick gets a minor change with big implications: instead of using a 20-pin header matching the ATtiny861 pinout, I've widened the board to give the XO Stick a standard Arduino shield connector (and some prototyping area). This opens the way for a port of the Arduino IDE (mentioned above), but it also means that the XO Stick can be mounted on top of an XOrduino. In a cost-conscious classroom environment, this allows a teacher to buy/make one copy of the XOrduino with all of its fancy peripherals (scratch sensors, robot support) and then give each student a copy of the cheaper XO Stick. The students share the XOrduino and swap out their XO Stick "brains" on top to control it or use its peripherals. Mating the two boards also makes it straightforward to program an XO Stick from an XOrduino, or to use the XO Stick's prototyping area to hack together a shield for the XOrduino.

The XOrduino gets a more exciting feature (hinted at above) -- enough peripherals to become the XO Turtle Bot! This is a very low-cost turtle robot based on a Tamiya motor assembly. All of the extra robot components are optional—you can populate just the parts you want—but a classroom can now make their XOrduinos (or XO Stick + XOrduino base) into standalone turtle robots, controlled by Scratch, Turtle Art, or Arduino code. The XO Turtle Bot revision adds a motor driver, two bump switches, a simple 3-cell power supply, and rotation sensors for the motors to the XOrduino. (Arnan Sipitakiat and Nussarin Nusen in their Robo-Blocks presentation for IDC 2012 explained that children find "turn for two seconds" hard to understand; we include motor sensors so that we can "turn 90 degrees" instead.) And of course because the robot is based on XOrduino, you can add whatever other sensors you like and write arduino/Scratch/Turtle Blocks code for it.

XOrduino A1 board on top of Tamiya Twin Motor Gearbox.   XOrduino A1 plugged into USB port; prototype XO Turtle Bot in the background.

I'm excited about the potential of low-cost robotics and the Arduino platform for education. If you are, too, let me send you a kit so you can help out!

Syndicated 2012-08-02 06:39:39 (Updated 2012-08-02 07:14:11) from Dr. C. Scott Ananian

Nell's Tinkrbook in Omo

This week I will be at the 2012 Interaction Design and Children conference in Bremen, Germany. I will be presenting the Growing Up With Nell paper as well as discussing the OLPC Foundation's literacy pilots in Ethiopia.

The Literacy Project is a collaboration between four different groups (as alluded to by the title of this post): the One Laptop per Child Foundation (“Nell”), the MIT Media Lab (“Tinkrbook”), the School of Education, Communication and Language Sciences at Newcastle University, and the Center for Reading and Language Research at Tufts University (“Omo”). The goal is to reach children even further from educational infrastructure than OLPC has ventured to date. In particular, the Ethiopia pilots are complete child-led bootstraps, attempting to teach kids to read English (an official language of Ethiopia) who neither speak English nor read in any language yet. There are no teachers in the village, and no literate adults either.

Adapting Nell to this environment has some challenges: how do we guide students through pedagogic material with stories if they don't yet understand the language of the stories we want to tell? But the essential challenge is the same: we have hundreds of apps and videos on the tablets and need to provide scaffolding and guidance to the bits most appropriate for each child at any given time, just as Nell seeks to guide children through the many activities included in Sugar. In the literacy project there is also a need for automated assessment tools: how can we tell that the project is working? How can we determine what parts of our content are effective in their role?

I'll write more about the Literacy Project in the coming weeks. As we've started to get data back, some of the lessons learned are familiar: kids do the strangest things! They learn how to do things we never knew they could do (or meant for them to) and often are motivated by pleasures which surprise us. For example, one app we deployed had a sphere which deflated with a sort of farting noise when the child picked the wrong answer. It turns out that the kids liked making the farting noise much more than they liked the response to the correct answer! Obvious in retrospect, but the lesson reminds us why we are pursuing an incremental development and data collection approach. Happily, the hardware itself has been a success: low hardware failure rates, solar powered charging is successful (although they prefer to charge the devices during the middle of the day; we'd expected them to do so overnight from storage batteries charged during the day), and they've mastered the touch interface very quickly on their own. The pilots have been running since February, and the kids are still very engaged with the content. So far, so good!

Smiling boy in Ethiopia Literacy Pilot Two girls in Ethiopia Literacy Pilot

Syndicated 2012-06-12 06:39:52 from Dr. C. Scott Ananian

9 Jun 2012 (updated 2 Aug 2012 at 19:07 UTC) »

Introducting the XOrduino! (and XO Stick)

I banged out two open hardware designs this week, designed for use with the OLPC XO laptops.

The first is the XOrduino, a stripped down low-cost Arduino-compatible board that plugs right into the XO's USB ports. But wait, there's more: it's also compatible with the Scratch Sensor Board, so you can use this device to control Scratch (and Turtle Art, once Firmata is ported). It should be compatible with the Arduino IDE and all Arduino Leonardo-compatible shields.

The board uses mostly through-hole parts, with one exception, and there are only 20 required components for the basic Arduino functionality, costing about $5 (from digikey, quantity 100). It is reasonable for local labor or even older kids to assemble by hand.

It's open hardware: Eagle design files are on github (schematic PDF, pcb PDF). I expect to have a small number of boards in a few weeks; let me know if you'd like one in exchange for help with hardware and software bring-up. Schematic and layout review also appreciated (I did the PCB routing late at night under time pressure leaning heavily on autoroute, it's certainly not the prettiest). And feedback from Arduino and Arduino shield hackers would also be welcome.

If $5 per student is too much money, there's also the XO Stick, my second board. It's based on the AVR Stick using the ATtiny85 processor and costs only $1/student. It's not quite as user-friendly as the Arduino-compatible board, but it can also be used to teach simple lessons in embedded electronics. For $0.12 more you can populate an ATtiny261A (though a '461 or '861 would be better) and get 13 I/O ports; this variant should be powerful enough to program other XO Sticks and perform XO maintenance tasks (accessing the serial console, debricking a laptop via SPI flash). The XO Stick is even easier for a kid to assemble themself: only 8 required components, all through-hole. (Sadly, my desire to shave every penny off the cost of this design meant that I couldn't use some of the symmetry tricks I invented for a 2012 Mystery Hunt puzzle to make the circuit impossible to assemble incorrectly.)

Same deal as the XOrduino: design files on github (schematic PDF, pcb PDF); I expect to have a few boards available to people who want to help make some software for them. Schematic and layout review is also appreciated!

Syndicated 2012-06-09 16:06:32 (Updated 2012-08-02 18:33:58) from Dr. C. Scott Ananian

12 Mar 2012 (updated 14 Mar 2012 at 01:09 UTC) »

Growing Up With Nell

Chris, Michael, and I just submitted a short paper describing our work on the XO-3 Nell project to this year's Interaction Design and Children conference. Give the preprint a read: Growing Up With Nell: A Narrative Interface for Literacy [pdf].

We're hard at work implementing Nell. We could use help in a number of areas: art, animation, story, user interface, javascript hacking, and probably others. For example, at the moment Chris and I are: drawing the characters, drawing user interface concepts, writing silly alphabet stories, animating the silly alphabet stories, doing the CSS/HTML layout to mock up designs, making some of the mock ups into functional demos, implementing HMM-based handwriting recognition in JavaScript, porting pyaiml to JavaScript, implementing an Apple Guide-style contextual help system on top of HTML widgets, and writing a integrated story editor (and stories about the story editor). I'd welcome volunteers for any of these tasks!

Syndicated 2012-03-12 20:55:35 (Updated 2012-03-14 00:28:51) from Dr. C. Scott Ananian

2012 Mystery Hunt

This year I was a member of Codex, the writing team for the 2012 Mystery Hunt. I'm going to describe some of the puzzles I wrote for "The Producers" hunt, in release order. BEWARE SPOILERS!

  1. One of the early theme proposals for our hunt was "Alice in Wonderland." Casting about for novel meta ideas, I hit upon the idea of a round with purely numeric answers, 1 through 29,394, which would resolve to words via "looking glass numbers"—that is, numbering all the words in "Through the Looking Glass". It occurred to me that you could make your numbering system self-descriptive if you used certain words; for example, if you wanted to make clear that hyphenated words should be counted as one (instead of two), you could include "great" and "half" on either side of "arm-chair". The numbering of "great" (164) and "half" (166) would make it clear that "arm-chair" should be treated as a single number (165).

    This didn't survive as a meta, but it eventually became a puzzle, called 1207 1370 (which translates to "Looking-Glass Words" using its enumeration system). It also served to ensure that teams had a good wordlist by the time they got to the Charles Dodgson meta...

  2. Blinkenlights. A recursive-structured puzzle inspired by (but not reaching the greatness of) Derek Kisman's Maze from Setec's '05 Hunt. If anyone is mourning the lack of Jonathan Coulton-related puzzles from this year's hunt, blame me: I stole the answer PROTECTORS which Andrew Lin had earmarked for a JoCo puzzle. ("Did I say overlords?")

  3. Caterpillars. I like giving physical objects to teams. This was another failed meta—you would have assembled the pieces out of words, then would have to assemble the jigsaw from the word-pieces. The location of the caterpillars' heads in the final assembly would spell out the final meta answer using an overlay. But the puzzle is more fun with tangible pieces, I think.

  4. B.J. Blazkowicz in ‘Wintertime for Hitler’. I was writing the meta for this round and trying to find non-dictionary words. I needed "CAR..." as a prefix to make the chess game work, which suggested CARMACK as an answer, and the puzzle just wrote itself from there. Scott Handelman contributed the title. This puzzle was going to be distributed on 3.5" disks (remember how I said I like giving teams physical objects?), but the last 3.5" floppy disk puzzle was Blue Steel in '06. (Redundant Obsolescence doesn't count, since the 5 1/4" disk was redundant.) The past six years have not been kind to the 3.5" floppy; ultimately we decided we didn't want to deny teams the pleasure of playing the game because they couldn't locate a floppy drive. It's more important that puzzles be fun than hard!

  5. Charles Lutwidge Dodgson meta. I began writing this puzzle immediately after the 2011 hunt, dissatisfied with the mechanism and final clue phrase of that year's Racking Your Brains. I thought I could write a better puzzle using Scrabble Solitaire as a mechanism.

    Slightly later it became part of the "Alice in Wonderland" theme proposal, with Jabberwocky words. Then I spent a couple of months away from the hunt, getting married.

    Upon returning we badly needed critic metas so I dusted off the puzzle, adding an Alice chess frontend yielding the tile string in order to make it a shell meta. The puzzle can still be solved as pure Scrabble Solitaire (ie, without the given "scores after each play") but it's easier for humans to solve with the frequent checkpoints given. For what it's worth, I constructed the chess game with a reasonably-deep alpha-beta search, so all the moves "make sense" as much as is possible given the constraints of the puzzle. And it ends in a clean checkmate, obviously... I have no idea how BENOISY snuck in there.

  6. Ben Bitdiddle meta. The idea of making an electronic circuit which was impossible to assemble incorrectly had been in my "Mystery Hunt ideas" folder for years. A coworker at OLPC mentioned the odd power-pin configuration of the PIC chips one day, which gave me the "flip" mechanism. Brainstorming with Andrew Lin brought it the rest of the way.

    I promise never to abuse an optoisolator in this way again.

    (Of course it turned out when constructing this puzzle that Ben Bitdiddle really needed to use the show answers CARPAL and THESOUTH because of their length in morse code, so I ended up having to rewrite parts of Dodgson to make Bitdiddle work. In the rewrite CARPAL became CARMACK... and B.J. Blazkowitcz was born.)

  7. JFK SHAGS A SAD SLIM LASS. One of my earliest puzzle submissions was, "A puzzle contained only in its title." Again, the fabulous Codex editor team turned this into a real puzzle.

Some puzzles I enjoyed editing:

  1. Revisiting History — I commissioned a Doctor Who-themed puzzle for the answer TORCHWOOD (see the final clue phrase for the reason why) and contributed the "location of the word 'who'" mechanism.

  2. Gibberish and More Gibberish. I liked the idea for this puzzle enough that I shoehorned a suitable answer into the Charles Dodgson meta... and then had to do some heavy lifting to get the puzzle finished and into the hunt.

  3. Sounds Good to Me. It was immediately obvious this was a brilliant idea from Seth Schoen. But the twin barriers of toki pona and hiragana threatened to make it unsolvable. I'd like to think I played a role in making this an accessible and solvable puzzle.

  4. Itinerant People of America. Same deal. Squiggles had bequeathed the world the facial expression described as, "That's my brain leaving out the back door while my face distracts you." My contribution here was solely instilling the fear of God into the authors. Scott Handleman describes how he and Emily Morgan took that advice and constructed a kick-ass puzzle.

And that's it for my puzzles! I also did a heck of a lot of other stuff for the hunt; I hope y'all enjoyed it. (My own favorite part was the wrap-up, since all my responsibilities had been discharged by then. I could just watch Patrick rock my hat and accordion, play along on ukulele, and sing tenor with Francis at the end.)

Syndicated 2012-01-18 23:09:41 (Updated 2012-01-18 23:11:16) from Dr. C. Scott Ananian

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