Robotic Acrobot Aces The Moves

January 12, 2023 by Anool Mahidharia 8 Comments

[Daniel Simu] is a performance artist, among many other things, and does acrobatic shows, quite often with a partner “flyer”. Training for his acts gets interrupted if his flyer partner is not available due to travel, injury or other reasons. This prompted him to build Acrobotics — a robotic assistant to make sure he can continue training uninterrupted.

He has some electronics and coding chops, but had to teach himself CAD so that he could do all of the design, assembly and programming himself. Acrobotics was developed as part of a Summer Sessions residency at V2_ (Lab for the Unstable Media) at Rotterdam in 2022.

The design is built around a mannequin body and things are quite simple at the moment. There are only two rotational joints for the arms at the shoulder, and no other articulations. Two car wiper motors rotate the two arms 360 deg in either direction. Continuous rotation potentiometers attached to the motors provide position feedback.

An ESP32 controls the whole thing, and the motors get juice via a pair of BTS7960 motor drivers. All of this is housed in a cage built from 15 mm aluminium extrusion and embedded in the torso of the mannequin. [Daniel] doesn’t enlighten us how the motor movements are synchronized with the music, but we do see a trailing cable attached to the mannequin. It’s likely the cable could be for power delivery, as well as some form of data or timing signals.

He’s working on the next version of the prototype, so we hope to see improved performances soon. There’s definitely scope for adding a suite of sensors – an IMU would help a lot to determine spatial orientation, maybe some ultrasonic sensors, or a LiDAR for object detection or mapping, or additional articulated joints at the elbows and wrists. We gotta love “feature creep”, right ?

Check out the two videos after the break – in the first one, he does an overview of the Acrobotics, and the second one is the actual performance that he did. Robot or not, it’s quite an amazing project and performance.
CAVEAT : We know calling this a “robot” is stretching the definition, by a lot, but we’re going to let it slip through.

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Generate Positivity With Machine Learning

August 6, 2020 by Bryan Cockfield 4 Comments

Gesture recognition and machine learning are getting a lot of air time these days, as people understand them more and begin to develop methods to implement them on many different platforms. Of course this allows easier access to people who can make use of the new tools beyond strictly academic or business environments. For example, rollerblading down the streets of Atlanta with a gesture-recognizing, streaming TV that [nate.damen] wears over his head.

He’s known as [atltvhead] and the TV he wears has a functional LED screen on the front. The whole setup reminds us a little of Deep Thought. The screen can display various animations which are controlled through Twitch chat as he streams his journeys around town. He wanted to add a little more interaction to the animations though and simplify his user interface, so he set up a gesture-sensing sleeve which can augment the animations based on how he’s moving his arm. He uses an Arduino in the arm sensor as well as a Raspberry Pi in the backpack to tie it all together, and he goes deep in the weeds explaining how to use Tensorflow to recognize the gestures. The video linked below shows a lot of his training runs for the machine learning system he used as well.

[nate.damen] didn’t stop at the cheerful TV head either. He also wears a backpack that displays uplifting messages to people as he passes them by on his rollerblades, not wanting to leave out those who don’t get to see him coming. We think this is a great uplifting project, and the amount of work that went into getting the gesture recognition machine learning algorithm right is impressive on its own. If you’re new to Tensorflow, though, we have featured some projects that can do reliable object recognition using little more than a Raspberry Pi and a camera.

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Manhattan Mystery Of Creepy Jingles And Random Noises Solved

December 15, 2018 by Dan Maloney 23 Comments

Here’s a puzzler for you: If you’re phreaking something that’s not exactly a phone, are you still a phreak?

That question probably never crossed the minds of New Yorkers who were acoustically assaulted on the normally peaceful sidewalks of Manhattan over the summer by creepy sounds emanating from streetside WiFi kiosks. The auditory attacks caused quite a stir locally, leading to wild theories that Russian hackers were behind it all. Luckily, the mystery has been solved, and it turns out to have been part prank, part protest, and part performance art piece.

To understand the exploit, realize that New York City has removed thousands of traditional pay phones from city sidewalks recently and replaced them with LinkNYC kiosks, which are basically WiFi hotspots with giant HDTV displays built into them. For the price of being blitzed with advertisements while strolling by, anyone can make a free phone call using the built-in VOIP app. That was the key that allowed [Mark Thomas], an old-school phreak and die-hard fan of the pay telephones that these platforms supplanted, to launch his attack. It’s not exactly rocket surgery; [Mark] dials one of the dozens of conference call numbers he has set up with pre-recorded audio snippets. A one-minute delay lets him crank the speakerphone volume up to 11 and abscond. The recordings vary, but everyone seemed most creeped out by the familiar jingle of the [Mr. Softee] ice cream truck franchise, slowed down and distorted to make it sound like something from a fever dream.

Yes, it’s a minimal hack, and normally we don’t condone the misuse of public facilities, even ones as obnoxious as LinkNYC appears to be. But it does make a statement about the commercialization of the public square, and honestly, we’re glad to see something that at least approaches phreaking again. It’s a little less childish than blasting porn audio from a Target PA system, and far less dangerous than activating a public safety siren remotely.

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Poetry In Motion With A Sand-Dispensing Dot Matrix Printer

September 3, 2017 by Dan Maloney 12 Comments

Hackaday gets results! Reader [John] saw our recent Fail of the Week post about a “sand matrix printer” and decided to share his own version, a sand-dispensing dot matrix printer he built last year.

Granted, [John]’s version is almost the exact opposite of [Vjie Miller]’s failed build, which sought to make depressions in the sand to print characters. [John]’s Sandscript takes a hopper full of dry, clean sand and dispenses small piles from six small servo-controlled nozzles. The hopper is mounted on a wheeled frame, and an optical encoder on one wheel senses forward motion to determine when to open each nozzle. As [John] slowly walks behind and to the side of the cart, a line of verse is slowly drizzled out onto the pavement. See it in action in the video below.

More performance art piece than anything else, we can see how this would be really engaging, with people following along like kids after the [Pied Piper], waiting to find out what the full message is. There’s probably a statement in there about the impermanence of art and the fleeting nature of existence, but we just think it’s a really cool build.

We’ve featured other sand writers before, like this high-resolution draw bot that also dispenses sandy verses, or this literal beach-combing art bot. Guess there’s just something about sand that inspires artists and hackers alike.

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32C3: 20 Oscillators In 20 Minutes

January 3, 2016 by Elliot Williams 25 Comments

In terms of implausible stand-up comedy, [Darsha]’s “20 Oscillators in 20 Minutes” is pretty far out there. First of all, she’s sitting down, with googly eyes on her multimeter, and five breadboards and a mess of 9V batteries laid out in front of her. “Has anybody built electronics before? Has anybody built electronics in front of this many people before? Yeah, so you’d better f**king be nice.” And she’s off!

“Square waves are really good for your speakers.” And a few seconds later, a lub-dub beat-frequency oscillator filled the hall. And then there’s the stand-up clichés: “Anyone in the audience from Norway?!” And “Anyone know what chip I’m using here?” (The 555.) A heckler, or participant, shouts up “What are you doing?” She responds “Building this!” and shows a sketch of the basic layout.

She baits the audience — “Do you want to ask me about duty cycles?” — and tells stories: “And then one time the solder fell in my lap and burned through my crappy jeggings. Who knows what jeggings are? Whooo!!” All the while the clicking gets louder and more complicated.

Then there’s the suspense. “11 minutes left? Shit, I dunno if I’m going to make it this time!” She’s visibly panicked. A question: “How do you protect the outputs from overvoltage?” “I don’t. (pause, laughter) I use some filter caps and just, well, hope that you guys have good insurance.”

Nearing the home stretch, there’s this quasi-rhythmic ticking and pulsing slowly building up in the background. She plugs in another capacitor, and the crowd spontaneously applauds. A little bit later, she shouts “Is it loud enough?” over the din and turns it down. At the end, the timing’s getting really tight, and she calls up someone to help from the audience.

We won’t spoil it, naturally. You’ll just have to watch it run to the end. We laughed, we cried. It was better than Schroedinger’s cats.

(We’d use hex inverters.)