Swarm Of Servos Plays This Robotic Glockenspiel

November 23, 2017 by 7 Comments

It’s the happiest sounding instrument in the marching band, and it’s got the best name to boot. It’s the glockenspiel, and if this robotic glockenspiel has anything to say about it, the days of human glockenspielists are numbered.

In its present prototype form, [Averton Engineering]’s “Spielatron” looks a little like something from a carousel calliope or an animatronic pizza restaurant band. Using a cast-off glockenspiel from a school music room as a base, the Spielatron uses four mallets to play all the notes. Each key is struck by a mallet secured to a base made of two servos. For lack of more descriptive mallet terminology, these servos provide pan and tilt so the mallet can strike the proper keys. The video below shows the Spielatron’s first recital.

An Arduino runs the servos and a MIDI interface; unfortunately, this version can’t play chords and is a little limited on note length, but upgrades are on the way. We’ve seen a robotic glockenspiel before with a similar design that might have some ideas for increasing performance. But if you’re looking for a more sublime sound, check out this dry ice-powered wind chime.

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FatPiBoy: Respin Game Boy With A Pop-Out Controller

November 20, 2017 by 5 Comments

Have you ever found yourself wishing you had a clone of the Game Boy, except it was actually twice as wide, and instead of holding it in your hands you pop a tiny separate controller out of the middle and play it that way? No? Well, neither have we. But that didn’t stop [Christian Reinbacher] from designing and building exactly that, and by the looks of the finished product, we have to say he might be onto something.

To be fair, the charmingly-named FatPiBoy is not really meant to be played like the GameBoy of yesteryear. It’s more like a game console with built in display; you prop the console up on something, and then remove the controller from the system and play that way.

The controller itself is a commercial product, the 8bitdo Zero, but [Christian] based the rest of the system on parts intended for the Adafruit PiGRRL. For the battery, [Christian] used a 4,500 mAh pack that was originally from his Nexus 7 tablet; a tip to keep in mind next time you’re looking for a big and cheap lithium-ion battery.

[Christian] notes that the case design isn’t perfect. There’s currently no external access to the Pi’s USB ports, and the recess for the 8bitdo Zero could be a few millimeters deeper. Still, we think he did an excellent job finishing the case and giving it a professional look; the case and controller look like nearly a perfect match.

This isn’t the first time we’ve seen a Raspberry Pi put on a GameBoy costume, but the FatPiBoy does bring something new to the table with its removable controller. Of course, if you think the controller [Christian] selected for this build is a bit too small, you can always substitute your own…

How Pure Is This Cup Of Joe? Coffee, Conspiracy, And Citizen Science

November 6, 2017 by 38 Comments

Have you ever thought about coffee purity? It’s more something you’d encounter with prescription or elicit drugs, but coffee is actually a rather valuable commodity. If a seller can make the actual grounds go a bit further by stretching the brew with alternative ingredients there becomes an incentive to cheat.

If this sounds like the stuff rumors are made of, that’s because it is! Here in Ho Chi Minh City there are age-old rumors a coffee syndicate that masterfully passes off adulterated product as pure, high-grade coffee. Rumors are one thing, but the local media started picking up on these suspicions and that caught my attention. I decided to look to simple chemistry to see if I could prove or disprove the story.

What we want to investigate is whether price and coffee purity are related. If they are, then after accounting for the effect of price, we will want to know whether proximity to the market where artificial coffee flavoring is sold has an effect on coffee purity.

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Coffee, Conspiracy, And Citizen Science: An Introduction To Iodometry

October 30, 2017 by 40 Comments

I take coffee very seriously. It’s probably the most important meal of the day, and apparently the largest overall dietary source of antioxidants in the United States of America. Regardless of whether you believe antioxidants have a health effect (I’m skeptical), that’s interesting!

Unfortunately, industrially roasted and ground coffee is sometimes adulterated with a variety of unwanted ‘other stuff’: corn, soybeans, wheat husks, etc. Across Southeast Asia, there’s a lot of concern over food adulteration and safety in general, as the cost-driven nature of the market pushes a minority of vendors to dishonest business practices. Here in Vietnam, one of the specific rumors is that coffee from street vendors is not actually coffee, but unsafe chemical flavoring agents mixed with corn silk, roasted coconut husks, and soy. Local news reported that 30% of street coffee doesn’t even contain caffeine.

While I’ve heard some pretty fanciful tales told at street side coffee shops, some of them turned out to be based on some grain (bean?) of truth, and local news has certainly featured it often enough. Then again, I’ve been buying coffee at the same friendly street vendors for years, and take some offense at unfounded accusations directed at them.

This sounds like a job for science, but what can we use to quantify the purity of many coffee samples without spending a fortune? As usual, the solution to the problem (pun intended) was already in the room:

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SpiderMAV drone perching from the ceiling

SpiderMAV Drone Shoots Webs To Perch And Stabilize

October 7, 2017 by 8 Comments

Introducing your friendly neighborhood SpiderMAV, a micro aerial vehicle that shoots webbing to enable it to hang from ceilings and stabilize itself horizontally using low power. It’s inspired by the Darwin’s bark spider that spins a circular web with anchor lines up to 25 meters (82 feet) long.

SpiderMAV perching and stabilizing modules

For the DJI Matrice 100 drone to hang from a ceiling, a compressed gas cylinder fires a magnet with a trailing polystyrene line up to a steel beam. The line can then be reeled in to the desired length. For horizontal stabilization, line-trailing magnets are fired horizontally instead and then reeled in to tension the lines.

To test the effectiveness of the system, a cross wind was produced using a fan. With the DJI’s attitude-hold mode, maximum X, Y and Z deviations were 136, 386 and 106 mm respectively. With the stabilization, however, the deviations were reduced to 47, 80 and 74 mm. The power requirements were also reduced to essentially nil. Watch it in action in the videos below.

SpiderMAV is the brainchild of Imperial College London’s Aerial Robotics Laboratory, led by [Mirko Kovac], and is still experimental. For example, a magnet release mechanism has yet to be built in. Perhaps a sharp tug by the reeling mechanism, or a sudden thrust by the drone would release the magnets. Or the permanent magnets could be replaced with electromagnets, provided the required current doesn’t offset the efficiency gains. What solutions can you come up with? Let us know in the comments.

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RaspiReader, An Open Source Fingerprint Reader

September 4, 2017 by 14 Comments

In 2008, the then German interior minister, [Wolfgang Schäuble] had his fingerprint reproduced by members of the German Chaos Computer Club, or CCC, and published on a piece of plastic film distributed with their magazine. [Schäuble] was a keen proponent of mass gathering of biometric information by the state, and his widely circulated fingerprint lifted from a water glass served as an effective demonstration against the supposed infallibility of biometric information.

Diagram showing the fingerprint reader's operation.
Diagram showing the fingerprint reader’s operation.

It was reported at the time that the plastic [Schäuble] fingerprint could fool the commercial scanners of the day, including those used by the German passport agency, and the episode caused significant embarrassment to the politician. The idea of “spoofing” a fingerprint would completely undermine the plans for biometric data collection that were a significant policy feature for several European governments of the day.

It is interesting then to read a paper from Michigan State University, “RaspiReader: An Open Source Fingerprint Reader Facilitating Spoof Detection” (PDF downloadable from the linked page) by [Joshua J. Engelsma], [Kai Cao], and [Anil K. Jain] investigates the mechanism of an optical fingerprint reader and presents a design using the ever-popular Raspberry Pi that attempts to detect and defeat attempts at spoofing. For the uninitiated is serves as a fascinating primer on FTIR (Frustrated Total Internal Reflection) photography of fingerprints, and describes their technique combining it with a conventional image to detect spoofing. Best of all, the whole thing is open-source, meaning that you too can try building one yourself.

If [Cao] and [Jain] sound familiar, maybe it’s from their Samsung Galaxy fingerprint hack last year, so it’s neat to see them at work on the defense side. If you think that fingerprints make good passwords, you’ve got some background reading to do. If you just can’t get enough fingerprints, read [Al Williams]’ fundamentals of fingerprint scanning piece from earlier this year.

Via Hacker News.