Building Your Own Tensegrity Structure

November 29, 2019 by 37 Comments

It seems that tensegrity structures are trending online, possibly due to the seemingly impossible nature of their construction. The strings appear to levitate without any sound reason, but if you bend them just the right way they’ll succumb to gravity. 

The clue is in the name. Tensegrity is a pormanteau of “tension” and “integrity”. It’s easiest to understand if you have a model in your hand — cut the strings and the structure falls apart. We’re used to thinking of integrity in terms of compression. Most man-made structures rely on this concept of engineering, from the Empire State Building to the foundation of apartment building.

Tensegrity allows strain to be distributed across a structure. While buildings built from continuous compression may not show this property, more elastic structures like our bodies do. These structures can be built on top of smaller units that continuously distribute strain. Additionally, these structures can be contracted and retracted in ways that “compressionegrities” simply can’t exhibit.

How about collapsing the structure? This occurs at the weakest point. Wherever the load has the greatest strain on a structure is where it will likely snap, a property demonstrable in bridges, domes, and even our bodies.

Fascinated? Fortunately, it’s not too difficult to create your own structures.

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Making Your Own Chain Sprockets, The Tidy Way

November 29, 2019 by 17 Comments

Chain sprockets are a key drivetrain component in a lot of builds. Unfortunately they can be difficult to source, particularly for those outside the reach of retailers like McMaster-Carr. In such situations, you might consider making your own.

The toothed profile on a chain sprocket can be produced in a simple manner by drawing a base circle, along with a series of circles spaced appropriately for the chain in question. This involves measuring the pitch and roller diameter of the chain. With these measurements in hand, a template can be created to produce the sprocket.

From there a series of holes are drilled to rough out the basic shape of the teeth, before the sprocket is then cut down to its appropriate outer diameter. The finishing work consists of chamfering the sprocket’s thickness, as well as the filing the sharp edges of the teeth for smooth engagement.

It’s a quick and easy method for producing sprockets with well-defined, accurate profiles. We’ve featured other rough and ready methods before, too. Video after the break.

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Dub Siren Synth Does It The Old School Way

November 29, 2019 by 18 Comments

There’s little that can compare to the sheer obnoxious thrill of mashing the DJ siren when its your turn behind the decks. We’ve certainly been guilty of abusing the privilege at local house parties, and unsurprisingly have not been invited back. If we ever get another shot, though, we’d be glad to have [lonesoulsurfer]’s dub siren at the ready.

This is a build for the old-school purists. There’s no microcontrollers or digital hardware here. The synth relies on two 555 timer ICs as the oscillators and an LM741 op-amp. These parts harken right back to the dawn of the integrated circuit era, and still do a great job in this application. There’s also a cheap reverb/echo module added in to fatten up the sound. It’s all laced up in an old CB radio enclosure, with the classic woodgrain applique doing much to add to the aesthetic.

It’s a build that’s simple enough for the electronics beginner, and would make a great tactile, analog addition to any DJ’s rig. If you need some wubwubs to go with your woowoos, then consider building a Ball of Dub, too.

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Landbeest, A Single Servo Walking Robot

November 29, 2019 by 14 Comments

Walking robots have a rich history both on and off the storied pages of Hackaday, but if you will pardon the expression, theirs is not a field that’s standing still. It’s always pleasing to see new approaches to old problems, and the Landbeest built by [Dejan Ristic] is a great example.

It’s a four-legged walker with a gait dictated by a cam-and-follower mechanism that allows it to perform the full range of leg movement with only one motor. Each cam can control more than one leg in synchronisation, and in his most recent prototype, there are two such mechanisms that work on opposite corners of a four-legged machine. The legs are arranged in such a way that the two corner-to-corner pairs pivot at their centres in a similar manner to a pair of scissors; allowing a servo to steer the robot as it walks.

The result certainly isn’t as graceful as [Theo Janssen]’s Strandbeest, from which it evidently takes inspiration for its name, but it’s no less capable for it. After the break you can see a video he’s posted which clearly illustrates its operation and demonstrates its ability to traverse obstacles.

The only thing that’s missing are the files and software should you wish to create your own. He’s unapologetic about this, pointing out that he’d prefer to wait until he is satisfied with it before letting it go. Since he’s put a lot of work in so far and shows no sign of stopping, we’re sure he’ll reach that point soon enough.

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DSP Spreadsheet: Talking To Yourself Using IQ

November 29, 2019 by 12 Comments

We’ve done quite a bit with Google Sheets and signal processing: we’ve generated signals, created filters, and computed quadrature signals. We can pull all that together into an educational model for two SDRs talking to each other, but it’s going to require two parts: modulation and demodulation. Guess what? We can do that with a spreadsheet.

The first step is to generate a reference clock for the carrier. You’ll need a cosine wave (I) and sine wave (Q). Of course, you also need the time base. That’s columns A-C in the spreadsheet and works like other signal generation we’ve seen.

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A Fantastic Frontier Of FPGA Flexibility Found In The 2019 Supercon Badge

November 29, 2019 by 7 Comments

We have just concluded a successful Hackaday Superconference where a highlight for many was digging into this year’s hardware badge. Shaped in the general form of a Game Boy handheld gaming console, the heart of the badge is a large FPGA opening up new and exciting potential for badge hacking.

Beyond our normal tools of compiling custom code or modifying hardware with a soldering iron, we now have the option to change core hardware behavior with Verilog. And people explored this new frontier to great effect, as seen at the badge hacking ceremony. (Video embedded below.)

FPGAs are not new, technically speaking, why are they exciting now? We can thank their recent growth in capability, their rapidly falling cost, and the relatively new availability of open source toolchains. These developments elevated FPGA into one of the most exciting trends in hardware today, so this year’s badge master [Sprite_TM] built an open FPGA playground for several hundred of his closest Supercon friends. Let’s take a look at what people were able to accomplish in just a few days using this unique and powerful hardware.

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Simplified AI On Microcontrollers

November 29, 2019 by 6 Comments

Artificial intelligence is taking the world by storm. Rather than a Terminator-style apocalypse, though, it seems to be more of a useful tool for getting computers to solve problems on their own. This isn’t just for supercomputers, either. You can load AI onto some of the smallest microcontrollers as well. Tensorflow Lite is a popular tool for this, but getting it to work on your particular microcontroller can be a pain, unless you’re using an Espruino.

This project adds support for Tensorflow to this class of microcontrollers without having to fuss around with obtuse build tools. Basically adding a single line of code creates an instance, all without having to compile anything or even reboot. Tensorflow is a powerful software tool for microcontrollers, and having it this accessible now is a great leap forward.

So, what can you do with this tool? The team behind this build is using Tensorflow on an open smart watch that can be used to detect hand gestures and many other things. They also opened up these tools for use in a browser, which allows use of the AI software and emulates an Espruino without needing a physical device. There’s a lot going on with this one, and it’s a bonus that it’s open source and ready to be turned into anything you might need, like turning yourself into a Street Fighter.