Flexures Make This Six-DOF Positioner Accurate To The Micron Level

It’s no secret that we think flexures are pretty cool, and we’ve featured a number of projects that leverage these compliant mechanisms to great effect. But when we saw flexures used in a six-DOF positioner with micron accuracy, we just had to dig a little deeper.

The device is known as the Hexblade, and it comes to us from the lab of [Jonathan Hopkins] at UCLA. We have to admit that at times, the video below feels a little like the “Turbo Encabulator” schtick — “three identical decoupled actuation limbs arranged in an axisymmetric configuration” may be perfectly descriptive, but it does not flow trippingly from the tongue. Hats off to [Professor Hopkins] for nailing the narration, though, and really, once you get a handle on the jargon, it all makes perfect sense. The platform is supported by a total of six flexures, which look like bent pieces of sheet metal but are actually cut from a solid block of material using wire EDM. Three of the flexures are oriented in the plane of the platform, while the other three are perpendicular to it. The far end of each flexure is connected to a voice-coil actuator that is surrounded by another flexure, this one in a parallelogram arrangement. The six actuators can move the platform smoothly through three linear translations (X, Y, and Z) and three rotations (roll, pitch, and yaw).
The platform’s range of motion is limited, but the advantages of using flexures as bearings are clear — there’s no backlash or hysteresis, and the voice coils can control the position of the stage to micron accuracy. Something like the Hexblade would be an ideal positioner for microscopy, and we can imagine an even smaller version, perhaps even a MEMS-fabricated one for nanomanufacturing applications. The original concept of the Hexblade serving as the print head for a fabrication robot for space applications is pretty cool, too, and we’d venture to say that a homebrew version of this probably isn’t out of reach either.

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Tree Forks As Natural Composite Joints In Architecture

A problem facing architects when designing complex three-dimensional structures lies in their joints, which must be strong enough to take the loads and vector forces applied by the structure, yet light enough not to dominate it. Many efforts have been made to use generative design techniques or clever composites to fabricate them, but as Dezeen reports, a team at MIT are exploring an unexpected alternative in the form of naturally occurring tree forks.

The point at which a tree branch forks from its trunk is a natural composite material formed of an interlocking mesh of wood grain fibres. Timber processors discard these parts of the tree as they interfere with the production of smooth timber, but the same properties that make them support the weight of a branch are it seems perfect for the architects’ needs.

The clever part of the MIT team’s work lies in scanning and cataloguing a library of forks, allowing them to be matched from the database to vertices in an architectural design. The forks are subject to minimal machining before being incorporated into the structure, and to prove it the MIT folks have made a test structure. It’s not uncommon to see medieval barns or half-timbered houses using curved pieces of wood in their natural shapes, so it’s not surprising to see that this 21st century innovation isn’t an entirely new technique.

Pico Chording Keyboard Is Simultaneously Vintage And New

On paper, chording — that’s pressing multiple keys to create either a single character or a whole word — looks like one of the best possible input methods. Maybe not the best for speed, at least for a while, but definitely good for conserving the total number of keys. Of course, fewer keys also makes for an easier time when it comes to building keyboards (as long as you don’t have to code the chording software). In fact, we would venture to guess that the hardest part of building your own version of [CrazyRobMiles]’s Pico Chord Keyboard would be teaching your fingers how to work together to chord instead of typing one at a time.

[CrazyRobMiles] took inspiration from the Cykey chording design used for the Microwriter and later, the Microwriter Agenda that also featured a qwerty blister keyboard. Both featured small screens above the six keys — one for each finger, and two for the thumb. While the original Microwriter ran on an 8-bit microprocessor, Pico Chord Keyboard uses — you guessed it — the Raspberry Pi Pico.

We love that [CrazyRobMiles] went with four 14-segment displays, which gives it a nice old school feel, but used transparent keycaps over Kailh switches. This is actually important, because not only do the LEDs show what mode you’re in (alpha vs. numeric vs. symbols), they also teach you how to chord each letter in the special training game mode. Be sure to check it out in the video after the break.

Isn’t it cool that we live in a world of relatively big keyboards with few keys and tiny keyboards with all the keys?

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ElectriPop Turns Cut Mylar Into Custom 3D Structures

Mylar has a lot of useful properties, and as such as see it pop up pretty often, not just in DIY projects but in our day-to-day lives. But until today, we’ve never seen a piece of Mylar jump up and try to get our attention. But that’s precisely the promise offered by ElectriPop, a fascinating project from Carnegie Mellon University’s Future Interfaces Group.

The core principle at work here is fairly simple. When electrostatically charged, a strip of Mylar can be made to lift up vertically into the air. Cut that strip down the center, and the two sides will repel each other and produce a “Y” shape. By expanding on that concept with enough carefully placed cuts, it’s possible to create surprisingly complex three dimensional shapes that pop up once a charge is applied. A certain degree of motion can even be introduced by adjusting the input power. The video after the break offers several examples of this principle in action: such as a 3D flower that either stands up tall or wilts in relation to an external source of data, or an avatar that flails its arms wildly to get the user’s attention.

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Screwed Up: Can Technology Be A Substitute For Regular Maintenance

The bane of life for anyone who possesses a well-used pile of spanners is the humble nut and bolt. Durable and easy to fasten, over our lifetimes we must screw and unscrew them by the million. When they do their job they’re great, but too often they seize up solid, or more alarmingly, gradually undo themselves over time due to vibration or thermal stress. There are a host of products such as locking nuts or thread sealant to deal with this problem, but the Fraunhofer Institute have an idea which might just remove the worry surrounding important fastenings. Their work has resulted in a solar-powered bolt with an embedded sensor that phones home when the connection loosens, allowing an engineer to be dispatched with a spanner to tighten it up.

The sensor itself is a washer which reports the force placed upon it, when this reduces an alert is sent. Communication is via Fraunhofer’s own MIoTy low-power wide-area network (LPWAN) protocol, but we’d imagine that one of the many competitor technologies could also serve.

This is an interesting idea that could no doubt result in targeted maintenance catching faulty fastenings early and averting disaster in the infrastructure projects such as bridges and wind turbines that they mention. We worry slightly though, because these types of structures have lives not in the few years of most tech products but in centuries. Will an IoT bolt head sensor still be phoning home in a few decades time, or will the system rely on old bolts being replaced at regular intervals of a decade? It’s not unknown for disasters to be the result of failures in fastenings a century old, so we sincerely hope that authorities in charge of whatever bridge relies on these won’t be tempted to skimp on their replacements. Perhaps a guy with a spanner every few years might be a more dependable option.

Retrotechtacular: How Television Worked In The 1950s

Watching television today is a very different experience from that which our parents would have had at our age, where we have high-definition digital on-demand streaming services they had a small number of analogue channels serving linear scheduled broadcasting. A particular film coming on TV could be a major event that it was not uncommon for most of the population to have shared, and such simple things as a coffee advert could become part of our common cultural experience. Behind it all was a minor miracle of synchronised analogue technology taking the signal from studio to living room, and this is the subject of a 1952 Coronet film, Television: How It Works!  Sit back and enjoy a trip into a much simpler world in the video below the break.

Filming a TV advert: 1950s housewife sells cooker
Production values for adverts had yet to reach their zenith in the 1950s.

After an introduction showing the cultural impact of TV in early-50s America there’s a basic intro to a cathode-ray tube, followed by something that may be less familiar to many readers, the Image Orthicon camera tube that formed the basis of most TV signals of that era.

It’s written for the general public, so the scanning raster of a TV image is introduced through the back-and-forth of reading a book, and then translated into how the raster is painted on the screen with the deflection coils and the electron gun. It’s not overly simplified though, for it talks about how the picture is interlaced and shows how a synchronisation pulse is introduced to keep all parts of the system working together.

A particularly fascinating glimpse comes in a brief mention of the solid copper co-axial cable and overland microwave links used to transmit TV signals across country, these concrete towers can still be seen today but they no longer have the colossal horn antennas we can see in the film.

A rather obvious omission in this film is the lack of any mention of colour TV, as while it would be late 1953 before the NTSC standard was formally adopted and early 1954 before the first few colour sets would go on sale. Colour TV would have been very much the Next Big Thing in 1952, but with no transmissions to watch and a bitter standards war still raging between the field-sequential CBS system and RCA’s compatible dot-sequential system that would eventually evolve into the NTSC standard¬† it’s not surprising that colour TV was beyond the consumer audience of the time.

Thus we’re being introduced to the 525-line standard which many think of as NTSC video, but without the NTSC compatible colour system that most of us will be familiar with. The 525-line analogue standard might have disappeared from our living rooms some time ago, but as the last few stations only came off-air last year we’d say it had a pretty good run.

We like analogue TV a lot here at Hackaday, and this certainly isn’t the first time we’ve gone all 525-line. Meanwhile for a really deep dive into the inner workings of TV signal timing, get ready to know your video waveform.

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Hackaday Podcast 167: Deadly Art Projects, Robot Lock Pickers, LED Horticulture, And Good Samaritan Repairs

Join Hackaday Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi for a review of all the tech that’s fit to print. Things kick off with an update about the Hackaday Prize and a brief account of the 2022 Vintage Computer Festival East. Then we’ll talk about an exceptionally dangerous art project that’s been making the rounds on social media, a smart tea kettle that gave its life so that others can hack their device’s firmware, some suspiciously effective plant grow lights, and the slippery slope of remote manufacturer kill switches. We’ll wrap things up with some thought provoking discussion about personal liability as it pertains to community repair groups, and a close look at what makes synthetic oil worth spending extra on.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments below!

Direct Download link.

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