Turning That Old Hoverboard Into A Learning Platform

June 3, 2018 by No comments

[Isabelle Simova] is building Hoverbot, a flexible robotics platform using Ikea plastic trays, JavaScript running on a Raspberry Pi and parts scavenged from commonly available hoverboards.

Self-balancing scooters a.k.a. Hoverboards are a great source of parts for such a project. Their high torque, direct drive brushless motors can drive loads of 100 kg or more. In addition, you also get a matching motor controller board, a rechargeable battery and its charging circuit. Most hoverboard controllers use the STM32F103, so flashing them with your own firmware becomes easy using a ST-link V2 programmer.

The next set of parts you need to build your robot is sensors. Some are cheap and easily available, such as microphones, contact switches or LDRs, while others such as ultrasonic distance sensors or LiDAR’s may cost a lot more. One source of cheap sensors are car parking assist transducers. An aftermarket parking sensor kit usually consists of four transducers, a control box, cables and display. Using a logic analyzer, [Isabelle] shows how you can poke around the output port of the control box to reverse engineer the data stream and decipher the sensor data. Once the data structure is decoded, you can then use some SPI bit-banging and voltage translation to interface it with the Raspberry Pi. Using the Pi makes it easy to add a cheap web camera, microphone and speakers to the Hoverbot.

Ikea is a hackers favourite, and offers a wide variety of hacker friendly devices and supplies. Their catalog offers a wide selection of fine, Swedish engineered products which can be used as enclosures for building robots. [Isabelle] zeroed in on a deep, circular plastic tray from a storage table set, stiffened with some plywood reinforcement. The tray offers ample space to mount the two motors, two castor wheels, battery and the rest of the electronics. Most of the original hardware from the hoverboard comes handy while putting it all together.

The software glue that holds all this together is JavaScript. The event-driven architecture of Node.js makes it a very suitable framework to use for Hoverbot. [Isabelle] has built a basic application allowing remote control of the robot. It includes a dashboard which shows live video and audio streams from the robot, buttons for movement control, an input box for converting text to speech, ultrasonic sensor visualization, LED lighting control, message log and status display for the motors. This makes the dashboard a useful debugging tool and a starting point for building more interesting applications. Check the build log for all the juicy details. Which other products from the Ikea catalog can be used to build the Hoverbot? How about a robotic Chair?

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3D Printed Clockwork Star Tracker

June 3, 2018 by 8 Comments

Astrophotography is one of those things you naturally assume must be pretty difficult; surely something so awesome requires years of practice and specialized equipment which costs as much as your car. You shake your fist at the sky (since you have given up on taking pictures of it), and move on with your life. Another experience you’ll miss out on.

But in reality, dramatic results don’t necessarily require sticker shock. We’ve covered cheap DIY star trackers before on Hackaday, but this design posted on Thingiverse by [Tinfoil_Haberdashery] is perhaps the easiest we’ve ever seen. It keeps things simple by using a cheap 24 hour clock movement to rotate a GoPro as the Earth spins. The result is a time-lapse where the stars appear to be stationary while the horizon rotates.

Using a 24 hour clock movement is an absolutely brilliant way to synchronize the camera with the Earth’s rotation without the hoops one usually has to jump through. Sure you could do with a microcontroller, a stepper motor, and some math. But a clock is a device that’s essentially been designed from the ground up for keeping track of the planet’s rotation, so why not use it?

If there’s a downside to the clock movement, it’s the fact that it doesn’t have much torque. It was intended to move an hour hand, not your camera, so it doesn’t take much to stall out. The GoPro (and other “action” cameras) should be light enough that it’s not a big deal; but don’t expect to mount your DSLR up to one. Even in the video after the break, it looks like the clock may skip a few steps on the way down as the weight of the camera starts pushing on the gears.

If you want something with a bit more muscle, we’ve recently covered a very slick Arduino powered “barn door” star tracker. But there’re simpler options if you’re looking to get some shots tonight.

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$6 Weather Station Goes Where You Do

June 3, 2018 by 24 Comments

We admit, we see a lot of weather stations. What makes [Mike Diamond’s] take on this old favorite interesting is that it is tiny enough to carry with you, and uses your cell phone as a hotspot to deliver its data. Of course, that assumes you have a phone that can act as a hotspot.

The parts are straightforward, a power supply, an ESP8266, and a weather sensor board. It looks as though you could easily slip the whole affair into a tube or maybe a 3D printed enclosure. We were a little concerned about the bare wire used, but as [Mike] points out you can use insulated wire if you like, and we’d encourage you to do so.

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Silicon Nanowires Create Flexible Photodetectors

June 3, 2018 by 5 Comments

Modern display and solar cell technologies are built with a material called Indium Tin Oxide (ITO). ITO has excellent optical transparency and electrical conductivity, and the material properties needed for integration in large-scale manufacturing. However, we’re not content with just merely “good enough” nowadays, and need better materials to build ever better devices. Graphene and carbon nanotubes have been considered as suitable replacements, but new research has identified a different possibility: nanowires.

Researchers from the Indian Association for the Cultivation of Science (IACS) and the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) in Ireland have demonstrated a seamless silicon nanowire junction that can be used for photodetector and display technology.

Before you get lost in the jargon, let’s take a step back. A nanowire is just a very narrow length of wire, on the order of 1 nanometer across. When silicon is used at this scale, electrical charges can become stuck (called “charge trapping”), which means that the holes and electrons are separated, allowing for transistors and photovoltaics. By controlling where these holes form in the nanowire, you can create a “seamless” junction without using any dopant materials to create impurities, as is done in modern CMOS transistors

These material properties allow the functionality of a junction, but it still needs to be easily and repeatably manufactured. To solve this problem, the team put the nanowire transistors on a flexible polymer, which should enable flexible nanowire applications, such as a roll-up screen.

The first step towards a display is a simple photodetector, just consisting of a basic P-N junction, but they hope this technology will eventually be useful in “smart windows” due to the junctions’ applicability to photodetectors and cameras. Moving to emitting light for displays or creating a solar cell using this technology will probably take some time.

Do you have any experience with different materials for creating junctions? What would you do with a small, transparent photodetector? We’ve featured homebrew solar cells before, as well as creating DIY semiconductors. We’ve also seen silver nanowires for wearable circuits.

[Via IEEE Spectrum]

Someone Set Us Up The Compiler Bomb

June 3, 2018 by 43 Comments

Despite the general public’s hijacking of the word “hacker,” we don’t advocate doing disruptive things. However, studying code exploits can often be useful both as an academic exercise and to understand what kind of things your systems might experience in the wild. [Code Explainer] takes apart a compiler bomb in a recent blog post.

If you haven’t heard of a compiler bomb, perhaps you’ve heard of a zip bomb. This is a small zip file that “explodes” into a very large file. A compiler bomb is a small piece of C code that will blow up a compiler — in this case, specifically, gcc. [Code Explainer] didn’t create the bomb though, that credit goes to [Digital Trauma].

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Bringing Back A Spectrum’s Rails

June 2, 2018 by 10 Comments

The Sinclair ZX Spectrum was to most Brits the computer to own in the early 1980s, it might not have had all the hardware features of its more expensive competitors but it had the software library that they lacked. Games came out for the Spectrum first, and then other platforms got them later. If you didn’t have a rubber keyboard and a Sinclair logo, you were nothing in the playground circa 1984. That low price though meant that in true Sinclair tradition a number of corners had been cut in the little micro’s design. Most notably in its power supply, all the various rails required by the memory chips came from a rather insubstantial single-transistor oscillator that is probably the most common point of failure for these classic machines.

[Tynemouth Software] had an Issue 2 Spectrum with a missing -5V rail, and has detailed both the power supply circuit used on these machines and the process of faultfinding and repairing this one. A single transistor oscillator drives a little ferrite-spool transformer from which the various supplies are rectified and filtered. Similar circuits appear in multiple generations of Sinclair hardware, where we might nowadays use a little switching regulator chip.

We’re taken through the various stages of faultfinding this particular circuit, and the culprit is found to be a faulty Zener diode. It’s certainly not the last dead Spectrum that will cross an enthusiast’s bench, but at least in this case, the fault was less obtuse than they sometimes can be in this much-loved but sometimes frustrating machine.

Sinclair enthusiasts might also appreciate the great man’s earliest work.

Universal music translation network

Facebook’s Universal Music Translator

June 2, 2018 by 20 Comments

Star Trek has its universal language translator and now researchers from Facebook Artificial Intelligence Research (FAIR) has developed a universal music translator. Much of it is based on Google’s WaveNet, a version of which was also used in the recently announced Google Duplex AI.

Universal music translator architectureThe inspiration for it came from the human ability to hear music played by any instrument and to then be able to whistle or hum it, thereby translating it from one instrument to another. This is something computers have had trouble doing well, until now. The researchers fed their translator a string quartet playing Haydn and had it translate the music to a chorus and orchestra singing and playing in the style of Bach. They’ve even fed it someone whistling the theme from Indiana Jones and had it translate the tune to a symphony in the style of Mozart.

Shown here is the architecture of their network. Note that all the different music is fed into the same encoder network but each instrument which that music can be translated into has its own decoder network. It was implemented in PyTorch and trained using eight Tesla V100 GPUs over a total of six days. Efforts were made during training to ensure that the encoder extracted high-level semantic features from the music fed into it rather than just memorizing the music. More details can be found in their paper.

So if you want to hear how an electric guitar played in the style of Metallica might have been translated to the piano by Beethoven then listen to the samples in the video below.

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