Android Controlled Labyrinth

[Pcdevltd] pulled an all-nighter to get his first Android Developer Kit project up and running. Basing the project off of the example that Google used when unveiling the new accessory development hardware, he set to work controlling a marble labyrinth game using his smart phone. What began at 7pm was wrapped up by 5am to produce the results seen in the video after the break.

These ball mazes use two knobs to pivot the playing surface, changing gravity’s pull on the ball to get it to go where you want. [Pcdevltd] pulled off the bottom on his labyrinth and installed two small servo motors. These connect to the Android Open Accessory Development Kit via a small cable. Connect that to the phone and you can then use the internal accelerometer to play the game. If you have an Android phone and an Arduino this should be pretty easy to replicate since we know you can already use the ADK with Arduino. Get to work on your own projects and don’t forget to send us a link to your project log.

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Motion Controlled Reddit Vote Sign.


A little while back I attended the largest east coast gathering of folks from the ever popular social news site, Reddit.com. Those of you familiar with Reddit already know that it is all about link aggregation. Users post links to interesting websites and material, and can then vote up or vote down content based on interest or relevance. Through the magical site algorithms original and interesting content is, as implied, aggregated up to the front page.  The whimsical nature of this big DC event lead many people to furnish signs of all types based on the culture of the site, internet memes, etc… The signs that really caught my attention were based primarily on the stylistic site layout, blowing up mail icons and other Reddit specific graphics.

The concept of using site graphics gave me the idea of being able to personally vote up or down other peoples’ signs. It was far too easy to just make a cardboard arrow, and I don’t have a color printer. I happened to have a shelved coffee table project involving orange and blue LEDs. Same colors as the arrows! Sweet. To make this project work I would have to work entirely from my project pile, there simply was no time to order anything from the internet. I managed to crank out a functional up/down voting sign in 3 days leading up to the gathering (and the morning of), here is what I did:

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Small POV Device Shows Off Some Big Features

We’ve already added the components needed to build [Rucalgary’s] tiny POV device to our next parts order. The little device sets a new standard for tiny persistence of vision boards. Instead of relying on the user to find the best speed and timing for swinging the board around, [Rucalgary] used an accelerometer. This is the point at which we’d usually groan because of the cost of accelerometers. We’re still groaning but this time it’s for a different reason.

The accelerometer used here is a Freescale MMA7660. It’s an i2c device at a super low cost of less than $1.50. The reason we’re still groaning is that it comes in a DFN-10 package that is a bit harder to solder than SOIC, but if you’ve got patience and a good iron it can be done. An ATmega48 drives the device, with 8 LEDs and one button for input. On the back of the board there’s a holder for a CR2032 coin cell battery and a female SIL pin header for programming the device.

Check out the video demonstration embedded after the break. We love it that the message spells and aligns correct no matter which way the little board is waved.

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Walking Motion Analysis Using Wii Remotes

WiiGait is not a political scandal, it’s a project that records motion data while walking. [Bilal Chishti] and [Zassa Kavuma] are strapping a Wii remote onto each leg and recording the sensor data while making video of the walker at the same time. The two are using an Ubuntu box to pull the sensor data from the Bluetooth-enabled devices and utilizing its built-in webcam for the video. They graph the data for each axis and we’re sure that syncing up data anomalies with the video is just a matter of matching timestamps.

So what good is this? The creators are keeping us in the dark about an end-goal for collected data; this may just be for the experience of using the hardware. But we could see it having uses in making distance runners more efficient, or teaching that bipedal robot how to balance.

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Paper Accelerometers For Pennies In The Works

Cheap paper accelerometers? Put us down for a dozen to start. They’re not quite ready for mass production yet but it looks like they’re on the way.

[George Whitesides] led a team to develop the new technology that uses simple manufacturing methods to produce the sensor seen above. Graphite and silver inks were screen printed onto heavy paper. The single limb sticking out from the body of the sensor is a separate piece of paper that bends the carbon area when force is applied. This changes the carbon’s resistance which is measured using a Wheatstone bridge constructed by gluing resistors to the device.

It sounds unsophisticated compared to most of the accelerometer modules we’re used to, but if you need a sensor that detects sudden motion this sounds like the perfect part. Now who wants to be the first person to replicate this in their basement?

[Thanks Fabien]

Amarino Makes Android Controlled Robots A Snap

[Lucas Fragomeni] is controlling this robot using the accelerometer on his Android phone (translated). He could have gone through our Android tutorials and developed a custom application but he took the shorter route and used Amarino, an ‘Android meets Arduino’ toolkit, to do it for him. [Lucas] combined an Arduino, a BlueSMiRF Bluetooth modem, and two servo motors to build his robot. Amarino lets him connect to that Bluetooth modem and send sensor data over the connection. In this case it’s only the accelerometer that he chose to use, but he could have gone with the touchscreen, or any other sensor the handheld has to offer. Using this code package got him up and running quickly, only requiring that he writes his own code to turn the received signals into servo motor control routines. See it in action after the break.

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Data Logging Football

[Ben Kokes] threw together a hardware package to capture data from a football. In the center of a Nerf football he made room for an accelerometer, gyroscope, and an electronic compass.  All three can capture 3-axis data and, along with the LEDs ringing the circumference, they’ve controlled by an XMEGA192 microcontroller.

This makes us think back to a time when baseballs with a built-in speed sensor first hit the market… does this hack have mass marketing potential? Perhaps, but only if the $225 sensor price tag were greatly reduced. When we first started reading the description we hoped that [Ben] had coded an interpreter that would render 3D playback video from the data. He hasn’t done that, but from the data graphs he did assemble we don’t think that functionality is out of the question. We’ll keep our fingers crossed.