Passive WiFi On Microwatts

February 26, 2016 by 30 Comments

A lot of you use WiFi for your Internet of Things devices, but that pretty much rules out a battery-powered deployment because WiFi devices use a lot of juice. Until now. Researchers at the University of Washington have developed a passive WiFi implementation that uses only microwatts per device.

Working essentially like backscatter RFID tags do, each node has a WiFi antenna that can be switched to either reflect or absorb 2.4 GHz radiation. Your cell phone, or any other WiFi device, responds to this backscattered signal. All that’s missing is a nice steady signal to reflect.

passive_wifi-shot0008A single, plugged-in unit provides this carrier wave for multiple WiFi sensor nodes. And here’s the very clever part of the research: to keep the carrier from overwhelming the tiny modulated signal that’s coming from the devices, the plugged-in unit transmits off the desired frequency and the battery-powered units modulate that at just the right difference frequency so that the resulting (mixed) frequency is in the desired WiFi band.

If you’re a radio freak, you’ll recognize the WiFi node’s action being just like a frequency mixer. That’s what the researchers (slightly mysteriously) refer to as the splitting of the analog transmission stage from the digital. The plugged-in unit transmits the carrier, and the low-power nodes do the mixing. It’s like a traditional radio transmitter, but distributed. Very cool.

There’s a bunch more details to making this system work with consumer WiFi, as you’d imagine. The powered stations are responsible for insuring that there’s no collision, for instance. All of these details are very nicely explained in this paper (PDF). If you’re interested in doing something similar, you absolutely need to give it a read. This idea will surely work at lower frequencies, and we’re trying to think of a reason to use this distributed transmitter idea for our own purposes.

And in case you think that all of this RFID stuff is “not a hack”, we’ll remind you that (near-field) RFID tags have been made with just an ATtiny or with discrete logic chips. The remotely-powered backscatter idea expands the universe of applications.

Thanks [Ivan] for the tip!

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Samsung ARTIK Dev Boards Start To Ship

February 26, 2016 by 23 Comments

Another week’s news, another single board computer aimed at Internet of Things applications is launched. This time it’s Samsung’s Artik 5, a platform they’ve been talking about for a while now but which you can now buy as a dev board from Digi-Key for $99.99. For that you get Wi-Fi, Bluetooth and Zigbee connectivity, a dual-core ARM Cortex A7 running at 1GHz, 512MB of memory, and 4GB of eMMC storage. There are the usual plethora of interfaces: GPIO, I2C, SPI, UART, SDIO, USB 2.0, JTAG, and analogue.

The single board computer marketplace is starting to look rather crowded, and with so many competitors to choose from at more reasonable prices you might ask yourself why the ARTIK could be of interest to a maker. And given that Samsung are positioning it in their literature on its increased security for use in commercial  applications such as IoT hubs, IP cameras and industrial and commercial lighting systems, you’d probably be on to something. If you were to make a very rough analogy with the Raspberry Pi range this has more in common with the Compute Module when it comes to intended marketplace than it does with the Pi Zero.

One answer to that question though could be that it is one of the first devices to support the Thread networking protocol for IoT devices. Thread is a collaboration between Google and a range of other interested parties that has been designed to deliver reliable and secure mesh networking for IoT devices in connected homes. As with all new connectivity protocols only time will tell whether Thread is the Next Big Thing, but it is interesting to note in this board nevertheless.

The ARTIK hasn’t made many waves as yet, though we covered the story when it was announced last year. It is worth mentioning that the ARTIK 5 is only the first of three platforms, the ARTIK 1 will be a tiny board with Bluetooth LE aimed at portable and wearable applications while the ARTIK 10 will be an octo-core powerhouse aimed at mulitmedia processing and network storage applications.

Variable Stiffness Joints For Robots And More

February 25, 2016 by 10 Comments

The human body has many miraculous capabilities that we often take for granted. One of the more subtle ones is the variable stiffness of your joints. In technical terms, stiffness refers to the ability to resist a load. Delicately manipulating an artist’s paint brush, for example, doesn’t require much load resistance, but does require fine control. However, that same artist might pick up a bowling ball with a stiffer joint (and, usually, less fine control).

[Christopher Churchill] and some colleagues have a novel mechanical device that can rapidly change stiffness. The device could have applications in robotics and other devices. It can also transmit or attenuate vibration since non-stiff joints don’t pass vibrations as easily as stiff ones.

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Oak Lamp Glows Bright

February 25, 2016 by 29 Comments

Looking for a way to spruce up your place with a touch of rustic-future-deco? Why not embed LEDs somewhere they were never designed for? [Callosciurini] had a nice chunk of oak and decided to turn it into a lamp.

He was inspired by a similar lamp that retails for over $1,000, so he figured he would make his own instead (business idea people?). The oak is a solid chunk measuring 40x40x45cm and what he did was route out an angled channel across all faces of the cube. This allowed him to installed a simple LED strip inside the groove — then he filled it with an epoxy/paint mix to give it that milky glow.

To finish it off he sanded the entire thing multiple times, oiled the wood, and sanded it again with a very fine grit. The result is pretty awesome.

Now imagine what you could do design-wise if you could fold wood to make a lamp? Well with this custom wood-folding saw-blade, the sky is the limit!

[via r/DIY]

Hacked Turntable Rotates Humans For 3D Scanning

February 25, 2016 by 12 Comments

If you are from the 70’s, you’ll probably remember the Disco Body Shaper or the Aerobic Body Shaper exerciser devices that were the rage of the day. Basically, Lazy Susan turntables on which humans could stand and twist away to burn fat. The results were suspect, but [Daniel Kucera] thought one of them would be ideal in 2016 to build a heavy-duty turntable to allow full body scanning.

He had already tried a few other ideas and failed, so it was worth giving this a shot, since it cost just 10 bucks to buy one. The plan was to use a motor to provide friction drive along the circumference of the turntable platform. For this, he used a high torque motor with a gear on the output shaft. From the looks of it, he attached a Meccano plate to the base, and mounted the motor to this plate. A large spring keeps the motor pressed against the rim of the turntable. A strip of rubber scavenged from a bicycle tube was glued along the side of the turntable to provide some friction to the gear drive. The turntable is placed on two thick pieces of foam, to provide clearance for the motor. We aren’t sure if a toothed gear is the best choice to drive this thing, but a hacker’s gotta use what he’s got. He’s clocking 190 seconds for a full rotation, but he still hasn’t posted any scan results from the Android scanner software that he is working on. This one, for sure, doesn’t qualify for a “it’s not a hack” comment.

CNC Scrapbooking With A Raspberry Pi

February 25, 2016 by 14 Comments

It is perhaps a surprise that the widespread adoption of CNC machinery in the home has not come from 3D printing or desktop mills, but as a quiet revolution in the crafting industry. CNC cutters for plastic or card have been around for quite a while now, and while the prospect of cutwork greetings cards might not set all maker pulses racing these cutters do have significant untapped potential in other directions. Perhaps you have to own a carburetor whose gaskets have been unavailable since the 1960s to truly appreciate that.

[James Muraca] has a KNK Force, something of an object of desire in the world of desktop CNC cutters. The computer inside the Force is a Raspberry Pi, so of course [James] set about investigating its potential for running his own software. His progress so far is on GitHub, a web interface through which you can upload and cut an SVG file, but his plans are more ambitious. He hopes to turn his machine into a complete PCB manufacturing station, able to both cut the PCB, and with the addition of a vacuum attachment to pick and place components.

The KNK Force is an interesting machine not just because it is powered by a Raspberry Pi. Its cutter head is a rotary tool with a Z axis, so it can perform more heavy-duty and complex cutting tasks than its competition. In addition it has a camera built-in, and it is this feature that [James] hopes to use in his PCB project.

We’ve covered plenty of cutter projects before, from projects turning CNC machines and pen plotters into vinyl cutters to using a cutter as a laser engraver and even cutting solder paste stencils with one. We look forward to further progress on [James’s] project.

Dr Noirimetla, Private Failure Investigator And The Mystery Of Galileo’s Pillars

February 25, 2016 by 115 Comments

One dark and stormy morning, Dr. Richard Noirimetla, private failure investigator, was sitting at his desk nursing his morning cup of joe. It was an addiction, but life, and engineering was hard. Intense eyes sat in a round dark-skinned face. An engineering degree from the prestigious Indian Institute of Technology hung from the wall in his sparse office. Lightning flashed outside of his window, as the rain began to beat even harder against his corner office windows.

His phone rang.

“Hello, Dr. Noirimetla, Private Failure Investigator here.” He said in deep, polite voice. “How may I help you?”

“Ah, I’m Chief of Manufacturing for Galileo Concrete Pillars Inc. We have a bit of a problem here. We used to see a failure rate above 33% for our concrete pillar operation. As part of our lean manufacturing efforts we tried to reduce that number through various improvements. However, we see a failure rate of almost 50% now. We expect foul play… from one of our suppliers. Can you come right away?” a worried man’s voice sounded over the phone.

“I see, that’s very troubling,” Noirimetla rumbled. “I’ll send over the contract detail. There will be an increased fee, but I’m on my way.”

“Sounds good, we’ll pay anything! Just get our operation up to standards!” The man bid a polite goodbye and hung up.
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