SandBot Happily And Tirelessly Rolls Patterns In Sand

The patience and precision involved with drawing geometric patterns in sand is right up a robot’s alley, and demonstrating this is [rob dobson]’s SandBot, a robot that draws patterns thanks to an arm with a magnetically coupled ball.

SandBot, SCARA version. The device sits underneath a sand bed, and a magnet (seen at the very top at the end of the folded “arm”) moves a ball bearing through sand.

SandBot is not a cartesian XY design. An XY frame would need to be at least as big as the sand table itself, but a SCARA arm can be much more compact. Sandbot also makes heavy use of 3D printing and laser-cut acrylic pieces, with no need of an external frame.

[rob]’s writeup is chock full of excellent detail and illustrations, and makes an excellent read. His previous SandBot design is also worth checking out, as it contains all kinds of practical details like what size of ball bearing is best for drawing in fine sand (between 15 and 20 mm diameter, it turns out. Too small and motion is jerky as the ball catches on sand grains, and too large and there is noticeable lag in movement.) Design files for the SCARA SandBot are on GitHub but [rob] has handy links to everything in his writeup for easy reference.

Sand and robots (or any moving parts) aren’t exactly a natural combination, but that hasn’t stopped anyone. We’ve seen Clearwalker stride along the beach, and the Sand Drawing Robot lowers an appendage to carve out messages in the sand while rolling along.

Just in Time for Halloween: Another Talking Skull

It isn’t a unique idea, but we liked [Eric Wiemers’s] take on the classic animated skull for Halloween. In addition to showing you the code and the wiring, the video spends some time discussing what the audio looks like and what has to happen to get it into a format suitable for the Arduino. You can see the spooky video, below.

Of course, this is also a 3D printing project, although the skull is off-the-shelf. We wondered if he felt like a brain surgeon taking the Dremel to the poor skull. To fix the two parts of the device, he used brass threaded inserts that are heat set, something we’ve seen before, but are always surprised we don’t see more often.

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Hybrid Robot Walks, Transforms, And Takes Flight

[Project Malaikat] is a 3D printed hybrid bipedal walker and quadcopter robot, but there’s much more to it than just sticking some props and a flight controller to a biped and calling it a day. Not only is it a custom design capable of a careful but deliberate two-legged gait, but the props are tucked away and deployed on command via some impressive-looking linkages that allow it to transform from walking mode to flying mode.

Creator [tang woonthai] has the 3D models available for download (.rar file) and the video descriptions on YouTube contain a bill of materials, but beyond that there doesn’t seem to be much other information available about [Malaikat]. The creator does urge care to be taken should anyone use the design, because while the robot may be small, it does essentially have spinning blades for hands.

Embedded below are videos that show off the robot’s moves, as well as a short flight test demonstrating that while control was somewhat lacking during the test, the robot is definitely more than capable of actual flight.

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Listen To A Song Made From Custom Nintendo LABO Waveform Cards

[Hunter Irving] has been busy with the Nintendo LABO’s piano for the Nintendo Switch. In particular he’s been very busy creating his own custom waveform cards, which greatly expands the capabilities of the hackable cardboard contraption. If this sounds familiar, it’s because we covered his original method of creating 3D printed waveform cards that are compatible with the piano, but he’s taken his work further since then. Not only has he created new and more complex cards by sampling instruments from Super Nintendo games, he’s even experimented with cards based on vowel sounds in an effort to see just how far things can go. By layering the right vowel sounds just so, he was able to make the (barely identifiable) phrases I-LIKE-YOU, YOU-LIKE-ME, and LET’S-A-GO.

Those three phrases make up the (vaguely recognizable) lyrics of a song he composed using his custom waveform cards for the Nintendo LABO’s piano, appropriately titled I Like You. The song is at the 6:26 mark in the video embedded below, but the whole video is worth a watch to catch up on [Hunter]’s work. The song is also hosted on soundcloud.

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The Little Cat That Could

Most humans take a year to learn their first steps, and they are notoriously clumsy. [Hartvik Line] taught a robotic cat to walk [YouTube link] in less time, but this cat had a couple advantages over a pre-toddler. The first advantage was that it had four legs, while the second came from a machine learning technique called genetic algorithms that surpassed human fine-tuning in two hours. That’s a pretty good benchmark.

The robot itself is an impressive piece inspired by robots at EPFL, a research institute in Switzerland. All that Swiss engineering is not easy for one person to program, much less a student, but that is exactly what happened. “Nixie,” as she is called, is a part of a master thesis for [Hartvik] at the University of Stavanger in Norway. Machine learning efficiency outstripped human meddling very quickly, and it can even relearn to walk if the chassis is damaged.

We have been watching genetic algorithm programming for more than half of a decade, and Skynet hasn’t popped forth, however we have a robot kitty taking its first steps.

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The 3D Printed Guitar

We just wrapped up the Musical Instrument Challenge in the Hackaday Prize, and that means we’re sorting through a ton of inventive electronic musical instruments. For whatever reason we can’t seem to find many non-electronic instruments. Yes, MPCs are cool, but so are strings and vibrating columns of air. That’s what makes this entry special: it’s a 3D printed physical guitar. But it’s also got a hexaphonic pickup, there are lights in the fretboard, and it talks to a computer for PureData processing.

First, the construction of this guitar. It’s mostly 3D printed, with the ‘frame’ of the body made in a Creality 3D printer. It’s a bolt-on neck with a telecaster body, but the core of this guitar — where the pickups and bridge attach — are made out of aluminum extrusion. Another piece of aluminum extrusion runs down the neck, which is clad in a 3D-printed ‘back’ that looks ‘comfortable enough’. The headstock is bolted onto the end of this neck, and it seems reasonably tolerant of having a hundred pounds or so of strings pulling on it. The bridge is also 3D printed, with the saddles integrated into the print. Conventional wisdom says this would sound terrible, but nylon saddles were a thing back in the day, so we’re just going to roll with it.

The electronics are where this project really shines. The pickup is a salvaged Roland GK3 hexaphonic deal, with six outputs for each string. This is sent into a Teensy with an audio path for each individual string. Audio processing happens in the guitar, and latency is under five milliseconds, which is quick enough to not be a terrible distraction.

Except for synths and drum machines and computers, the last fifty or so years of technological progress hasn’t really made it to the world of musical instruments. Guitarists, especially, are technophobes who hate everything invented after 1963. While the neck of [Frank]’s ElektroCaster probably doesn’t feel great, this is a really interesting instrument and a great entry to the Hackaday Prize.

Smartphone Mod Goes Out On A Limb

The modern smartphone has a variety of ways to interact with its user – the screen, the speakers, and of course, the vibration motor. But what if your phone could interact physically? It might be unnerving, but it could also be useful – and MobiLimb explores exactly this possibility.

Yes, that’s right – it’s a finger for your mobile phone. MobiLimb has five degrees of freedom, and is built using servomotors which allow both accurate movement as well as positional feedback into the device. Additionally, a touch-sensitive potentiometer is fitted, allowing the robofinger to respond to touch inputs.

The brains behind the show are provided by an Arduino Leonardo Pro Micro, and as is usual on such projects, the mechanical assembly is 3D printed – an excellent choice for producing small, complex parts. Just imagine the difficulty of trying to produce robotic fingers with classic machine tools!

The project video shows many different possibilities for using the MobiLimb – from use as a basic notification device, to allowing the smartphone to crawl along a table. We frankly can’t wait until there’s a fully-functional scorpion chassis to drop an iPhone into – the sky really is the limit here.

Interested in other unique ways to interact with your smartphone? Check out these nifty 3D printed physical buttons.