Controlling This Smartwatch is All in the Wrist

Smartwatches are pretty great. In theory, you’ll never miss a notification or a phone call. Plus, they can do all kinds of bio-metric tracking since they’re strapped to one of your body’s pulse points. But there are downsides. One of the major ones is that you end up needing two hands to do things that are easily one-handed on a phone. Now, you could use the tip of your nose like I do in the winter when I have mittens on, but that’s not good for your eyes. It seems that the future of smartwatch input is not in available appendages, but in gesture detection.

Enter WristWhirl, the brain-child of Dartmouth and University of Manitoba students [Jun Gong], [Xing-Dong Yang], and [Pourang Irani]. They have built a prototype smartwatch that uses continuous wrist movements detected by IR proximity sensors to control popular off-the-shelf applications. Twelve pairs of dirt-cheap IR sensors connected to an Arduino Due detect any of eight simple gestures made by the wearer to do tasks like opening the calendar, controlling a music player, panning and zooming a map, and playing games like Tetris and Fruit Ninja. In order to save battery, a piezo senses pinch between the user’s thumb and forefinger and uses this input to decide when to start and stop gesture detection.

According to their paper (PDF warning), the gesture detection is 93.8% accurate. To get this data, the team had their test subjects perform each of the eight gestures under different conditions such as walking vs. standing and doing either with the wrist in watch-viewing position or hanging down at their side. Why not gesture your way past the break to watch a demo?

If you’re stuck on the idea of playing Tetris with gestures, there are other ways.

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Pulling Music Out Of The Airwaves

RADIO WONDERLAND is a one-man band with many famous unintentional collaborators. [Joshua Fried]’s shows start off with him walking in carrying a boombox playing FM radio. He plugs it into his sound rig, tunes around a while, and collects some samples. Magic happens, he turns an ancient Buick steering wheel, and music emerges from the resampled radio cacophony.

It’s experimental music, which is secret art-scene-insider code for “you might not like it”, but we love the hacking. In addition to the above-mentioned steering wheel, he also plays a rack of shoes with drumsticks. If we had to guess, we’d say rotary encoders and piezos. All of this is just input for his computer programs which take care of the sampling, chopping, and slicing of live radio into dance music. It’s good enough that he’s opened for [They Might Be Giants].

Check out the videos (embedded below) for a taste of what a live show was like. There are definitely parts where the show is a little slow, but they make it seem cooler when a beat comes together out of found Huey Lewis. We especially like the “re-esser” routine that hones in on the hissier parts of speech to turn them into cymbals. And if you scan the crowd in the beginning, you can find a ten-years-younger [Limor Fried] and [Phil Torrone].

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Navigation Thing: Four Days, Three Problems, and Fake Piezos

The Navigation Thing was designed and built by [Jan Mrázek] as part of a night game activity for high school students during week-long seminar. A night-time path through a forest had stations with simple tasks, and the Navigation Thing used GPS, digital compass, a beeper, and a ring of RGB LEDs to provide a bit of “Wow factor” while guiding a group of students from one station to the next. The devices had a clear design direction:

“I wanted to build a device which a participant would find, insert batteries, and follow the beeping to find the next stop. Imagine the strong feeling of straying in the middle of the night in an unknown terrain far away from civilization trusting only a beeping thing you found. That was the feeling I wanted to achieve.”

The Navigation Things (there are six in total) guide users to fixed waypoints with GPS, a digital compass, and a ring of WS2812 LEDs — but the primary means of feedback to the user is a beeping that gets faster as you approach the destination. [Jan] had only four days to make all six units, which was doable. But as most of us know, delivering on a tight deadline is often less about doing the work you know about, and more about effectively handling the unexpected obstacles that inevitably pop up in the process.

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Homemade E-Drums Hit All The Right Notes

In our eyes, there isn’t a much higher calling for Arduinos than using them to make musical instruments. [victorh88] has elevated them to rock star status with his homemade electronic drum kit.

The kit uses an Arduino Mega because of the number of inputs [victorh88] included. It’s not quite Neil Peart-level, but it does have a kick drum, a pair of rack toms, a floor tom, a snare, a crash, a ride, and a hi-hat. With the exception of the hi-hat, all the pieces in the kit use a piezo element to detect the hit and play the appropriate sample based on [Evan Kale]’s code, which was built to turn a Rock Band controller into a MIDI drum kit. The hi-hat uses an LDR embedded in a flip-flop to properly mimic the range of an actual acoustic hi-hat. This is a good idea that we have seen before.

[victorh88] made all the drums and pads out of MDF with four layers of pet screen sandwiched in between. In theory, this kit should be able to take anything he can throw at it, including YYZ. The crash and ride cymbals are MDF with a layer of EVA foam on top. This serves two purposes: it absorbs the shock from the sticks and mutes the sound of wood against wood. After that, it was just a matter of attaching everything to a standard e-drum frame using the existing interfaces. Watch [victorh88] beat a tattoo after the break.

If you hate Arduinos but are still reading for some reason, here’s a kit made with a Pi.

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Rainy Day Fun by Calculating Pi

If you need a truly random event generator, just wait till your next rainstorm. Whether any given spot on the ground is hit by a drop at a particular time is anyone’s guess, and such randomness is key to this simple rig that estimates the value of pi using raindrop sensors.

You may recall [AlphaPhoenix]’s recent electroshock Settlers of Catan expeditor. The idea with this less shocking build is to estimate the value of pi using the ratio of the area of a square sensor to a circular one. Simple piezo transducers serve as impact sensors that feed an Arduino and count the relative number of raindrops hitting the sensors. In the first video below, we see that as more data accumulates, the Arduino’s estimate of pi eventually converges on the well-known 3.14159 value. The second video has details of the math behind the method, plus a discussion of the real-world problems that cropped up during testing — turns out that waterproofing and grounding were both key to noise-free data from the sensor pads.

In the end, [AlphaPhoenix] isn’t proving anything new, but we like the method here and can see applications for it. What about using such sensors to detect individual popcorn kernels popping to demonstrate the Gaussian distribution? We also can’t help but think of other ways to measure raindrops; how about strain gauges that weigh the rainwater as it accumulates differentially in square and circular containers? Share your ideas in the comments below.

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Two Pins for the Price of One

One of the most common problems in the world of microcontrollers is running out of resources. Sometimes it’s memory, where the code must be pared down to fit into the flash on the microcontroller. Other times, as [Fabien] found out when he ran out of pins, the limitations are entirely physical. Not one to give up, he managed to solve the problem by using one pin for two tasks. (Google Translate from French)
During a recent project, [Fabien] realized he had forgotten to add a piezo buzzer to his project. All of the other pins were in use, though, so his goal was to use one of the input pins to handle button presses but to occasionally switch to output mode when the piezo buzzer was needed. After all, the button is only used at certain times, and the microcontroller pin sits unused otherwise. After a few trials, he has a working solution that manages to neither burn out itself nor the components in the circuit, and none of the components interfere with the other’s normal operation.
While it isn’t the most technically advanced thing we’ve ever seen here, it is a great example of using the tools at your disposal to elegantly solve a problem. More than that, though, it’s a thorough look into the details of pull-up and pull-down resistors, how microcontrollers see voltage as logic levels, and how other pieces of hardware interact with microcontrollers of all different types. This is definitely worth a read, especially if you are a beginner in this world.

Sonic 3D Printer Auto Bed Leveling Makes a Swoosh

3D Printering: the final frontier. These are the voyages of another 3D printer hack. Its mission: to explore strange new ways of leveling a print bed.

So far, we’ve had servo probes, Allen key probes, Z-sled probes, inductive and capacitive contactless switches, just to name a few. All of them allow a 3D printer to probe its print bed, calculate a correction plane or mesh, and compensate for its own inherent, time variant, inaccuracies.

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