E-Dermis: Feeling At Your (Prosthetic) Fingertips

June 24, 2018 by No comments

When we lose a limb, the brain is really none the wiser. It continues to send signals out, but since they no longer have a destination, the person is stuck with one-way communication and a phantom-limb feeling. The fact that the brain carries on has always been promising as far as prostheses are concerned, because it means the electrical signals could potentially be used to control new limbs and digits the natural way.

A diagram of the e-dermis via Science Robotics.

It’s also good news for adding a sense of touch to upper-limb prostheses. Researchers at Johns Hopkins university have spent the last year testing out their concept of an e-dermis—a multi-layer approach to expanding the utility of artificial limbs that can detect the curvature and sharpness of objects.

Like real skin, the e-dermis has an outer, epidermal layer and an inner, dermal layer. Both layers use conductive and piezoresistive textiles to transmit information about tangible objects back to the peripheral nerves in the limb. E-dermis does this non-invasively through the skin using transcutaneous electrical nerve stimulation, better known as TENS. Here’s a link to the full article published in Science Robotics.

First, the researchers made a neuromorphic model of all the nerves and receptors that relay signals to the nervous system. To test the e-dermis, they used 3-D printed objects designed to be grasped between thumb and forefinger, and monitored the subject’s brain activity via EEG.

For now, the e-dermis is confined to the fingertips. Ideally, it would cover the entire prosthesis and be able to detect temperature as well as curvature. Stay tuned, because it’s next on their list.

Speaking of tunes, here’s a prosthetic arm that uses a neural network to achieve individual finger control and allows its owner to play the piano again.

Thanks for the tip, [Qes].

Laser Draws Weather Report

June 23, 2018 by 13 Comments

Have you ever wished that a laser could tell you the weather? If you have, then [tuckershannon] has you covered. He’s created a machine that uses a laser and some UV sensitive paper to draw the temperature and a weather icon! And that’s not all! It’s connected to the internet, so it can also show the time and print out messages.

Building on [tuckershannon]’s previous work with glow-in-the-dark drawing, the brains inside this machine is a Raspberry Pi Zero. The laser itself is a 5mw, 405nm laser pointer with the button zip-tied down. Two 28BYJ-48 stepper motors are used to orient the laser, one for the rotation and another for the height angle. Each stepper motor is connected to a motor driver board and then wired directly to the Pi.

The base and arm that holds the laser were designed in SolidWorks and then 3d printed. The stepper motors are mounted perpendicular to one another and then the laser pointer mounted at the end. The batteries have been removed from the laser and the terminals are also wired directly to the raspberry pi. The Pi is then connected to Alexa via IFTTT so that it can be controlled by voice from anywhere.

The real beauty of [tucker]’s laser drawing machine is that is will draw out the temperature and weather icon, as well as drawing the time in either digital or analog forms! We’ve seen [tuckershannon]’s work before. The precursors to this project were his clock which uses a robotic arm with a UV LED on it to draw the time and another clock which uses similar robotic arm only with a laser attached. Let’s hope we get to see the rest of [tucker]’s progress!

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Is This The World’s Smallest Computer?

June 23, 2018 by 34 Comments

How small could you make a computer? In a way, that’s a question that requires that a computer be defined, because you could measure the smallest computer simply in terms of the smallest area of silicon required to create a microprocessor. So perhaps it’s better to talk about a smallest working computer. Recent entries in the race for the smallest machine have defined a computer as a complete computer system which holds onto its program and data upon power-down, but this remains one that is hotly debated. You might for instance debate as to whether that definition would exclude machines such as the crop of 1980s home computers that didn’t store their programs and data, was your Sinclair Spectrum not a computer?

At the University of Michigan they have opted for the simpler definition with their latest entry in the race to be the tiniest. Their latest machine packs an ARM Cortex M0 into a 0.3mm cube, along with photoreceptors and LEDs for programming, data throughput, and power. It is designed to be a temperature sensor and logger for medical implantation, but it stands more as a demonstration of technological prowess than as a usable product.

Pictures of a tiny computer “dwarfed by a grain of rice” make for good mass media consumption but where’s the relevance for us? The interesting part comes from the tantalizing glimpse of its construction: this is a hybrid device upon which we can see the optoelectronic components have been wire-bonded. Unfortunately the paper, catchily titled “A 0.04mm3 16nW Wireless and Batteryless Sensor System with Integrated Cortex-M0+ Processor and Optical Communication for Cellular Temperature Measurement” does not appear to be free-to-view online, so we don’t have any more information. We wish that such feats were possible within our community, but suspect those days are still pretty far away.

Roll Your Own Trackball Mouse

June 23, 2018 by 7 Comments

What do you do when you’re into trackball mice, but nothing out there is affordable or meets all your murine needs? You build one, of course. And if you’re like [Dangerously Explosive], who has a bunch of old optical mice squeaking around the shop, you can mix and match them to build the perfect one.

The mouse, which looks frozen mid-transformation into a rodential assassin, is a customized work of utilitarian art. Despite the excellent results, this project was not without its traps. [Dangerously] got really far into the build before discovering the USB interface chip was dead. Then he tried to sculpt a base out of Plasticine and discovered he’d bought the one kind of clay that can’t be baked. After trying his hand at making homemade salt dough, he painstakingly whittled a base from scrap pine using a drill and a hacksaw.

Every bit of this mouse is made from recycled bits, which, if you pair that with the paint job and the chosen shade of blinkenlights, makes this a green mouse on three levels. One of the two parts of this mouse that isn’t literally green, the cord, is still ecologically sound. [Dangerously] wanted a really long tail, so he scavenged a charger cable built for fruity hardware and threaded it through a hollowed-out piece of purple paracord.

We love the thumb-adjacent scroll wheel and the trackball itself, which is a ping pong ball painted black. The cool part is the guide it rolls around in. [Dangerously] spent a long time hand-whittling the perfect size hole in a particularly wide mouse palm rest. All that plastic shaving paid off, because the action is smooth as Velveeta.

[Dangerously] certainly designed this mouse to fit his preferences, and ergonomics seem a bit secondary. For a truly custom fit, try using whatever passes for Floam these days.

ROPS Will Be The Board X86 Robot Builders Are Waiting For

June 23, 2018 by 29 Comments

If your robot has outgrown a Raspberry Pi and only the raw computing power of an x86 motherboard will suffice, you are likely to encounter a problem with its interfaces. The days of ISA cards are long gone, and a modern PC is not designed to easily talk to noisy robot hardware. Accessible ports such as USB can have interfaces connected to them, but suffer from significant latency in the process.

A solution comes from ROPS, or Robot on a PCI-e Stick, a card that puts an FPGA on a blazing-fast PCI-e card that provides useful real-world interfaces such as CAN and RS485 and a pile of I/O lines as well as an IMU, barometer, and GPS. If you think you may have seen it before then you’d be right, it was one of the first-round winners of the Open Hardware Design Challenge. They’re very much still at the stage of having an FPGA dev board and working out the software so there aren’t any ROPS boards to look at yet, but this is a project that’s going somewhere, and definitely one to watch.

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Arduino And Pidgin C++

June 23, 2018 by 87 Comments

What do you program the Arduino in? C? Actually, the Arduino’s byzantine build processes uses C++. All the features you get from the normal libraries are actually C++ classes. The problem is many people write C and ignore the C++ features other than using object already made for them. Just like traders often used pidgin English as a simplified language to talk to non-English speakers, many Arduino coders use pidgin C++ to effectively code C in a C++ environment. [Bert Hubert] has a two-part post that isn’t about the Arduino in particular, but is about moving from C to a more modern C++.

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Digitizing Domesday Disks

June 23, 2018 by 47 Comments

After the Norman invasion of England, William the Conqueror ordered a great reckoning of all the lands and assets owned. Tax assessors went out into the country, counted sheep and chickens, and compiled everything into one great tome. This was the Domesday Book, an accounting of everything owned in England nearly 1000 years ago. It is a vital source for historians and economists, and one of the most important texts of the Middle Ages.

In the early 1980s, the BBC set upon a new Domesday Project. Over one million people took part in compiling writings on history, geography, and social issues. Maps were cataloged, and census data recorded. All of this was printed on a LaserDisk, meant to be played on an Acorn BBC Master. Now, 30 years on, hardly anyone can read the BBC Domesday Project. Let that be a lesson, kids: follow [Jason Scott] on Twitter.

Even though Acorn computers and SCSI LaserDisks and coprocessors are dying, that doesn’t mean the modern Domesday Disk is lost to the sands of time. This project aims to duplicate the Domesday Disk, and in the process provide a means to archive all LaserDisks. It’s a capture card for LaserDisks, and it also means we can finally make a good rip of the un-specalized Star Wars.

The Domesday Duplicator is a shield that plugs into an Altera DE-0 Nano FPGA board and a Cypress FX3 USB board. The Duplicator itself serves as an analog capture card complete with an RF amplifier and a 40 MSPS ADC — fast enough for any analog video signal. With the 50 Ohm input, it will work with most LaserDisk players, ultimately preserving this incredible historical archive from the early 80s.