Robot Joints Go Modular With This Actuator Project

[John Lauer] has been hard at work re-thinking robot arms. His project to create modular, open source actuators that can be connected to one another to form an arm is inspiring, and boasts an impressively low parts cost as well. The actuators are each self-contained, with an ESP32 and a design that takes advantage of the form factors of inexpensive modules and parts from vendors like Aliexpress.

Flex spline in action, for reducing backlash

Each module has 3D printed gears (with an anti-backlash flex spline), an RGB LED for feedback, integrated homing, active cooling, a slip ring made from copper tape, and a touch sensor dial on the back for jogging and training input. The result is a low backlash, low cost actuator that keeps external wiring to an absolute minimum.

Originally inspired by a design named WE-R2.4, [John] has added his own twist in numerous ways, which are best summarized in the video embedded below. That video is number three in a series, and covers the most interesting developments and design changes while giving an excellent overview of the parts and operation (the video for part one is a basic overview and part two shows the prototyping process, during which [John] 3D printed the structural parts and gears and mills out a custom PCB.)

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Hack My Wired Heart

Liner notes? Passé. In Berlin, the release of a special edition synth-wave record came with an accompanying experimental synthesizer called Wired Heart.

At the core of this adorable heart-shaped synth, designed by music technology enthusiast [tobi tubbutec], is the classic 74HCT14 chip with six Schmitt trigger oscillators. The bright red PCB has eight gold touch and humidity sensing pads that activate and modulate these oscillators. As well as changing the sounds by playing with pressure and conductive liquids you can use the six sets of header pins on board to plug in your own components for noisy experimentation. Wired Heart ships with LEDs, photoresistors and a potentiometer, but we’ve also plugged our own DIY fabric pressure sensors into this synth to make some excellent electronic sounds.

In the Hackaday.io post linked above, [tobi tubbutec] walks us through a number of the circuit design decisions he made while prototyping his “cardiotronic human-touch hexoscillatric stereo esoteric snythespacer”. We enjoyed his creative and sometimes unconventional designs, from his inclusion of non-functioning traces for aesthetic reasons to his chosen method of hard syncing — injecting a small pulse of one oscillator into the other. If you want to examine his layout in more detail, [tobi tubbutec] has helpfully included the KiCad schematic file in his write up.

This adorable, hackable synth caught our eye at this year’s SuperBooth — an annual indie electronic music conference in Berlin that’s well worth checking out if odd noises and handmade electronics are your thing —  but it’s recently been listed on Tindie too. To listen to the upbeat synth-wave record Wired Heart originally shipped with, visit the artist Hyboid’s bandcamp.

If you’re interested in experimental musical instruments and synthy chip tune you’ll also love [jarek319]’s Sega Genesis synthesiser.

Check out a demo of the Wired Heart synth in the video after the break.

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ESP32 Alarm Clock Doesn’t Skimp On The Features

The ESP family of microcontrollers is absolutely on fire right now, with a decent chunk of the projects that come our way now based on one of the impossibly cheap WiFi-enabled boards. In fact, they are so cheap and popular that we’ve started to see a somewhat unexpected trend; people have a tendency to use them as drop-in replacements, despite the more modern boards being considerably more powerful than required. The end result is a bunch of projects in which the ESP is simply underutilized. It’s not a big deal, but somewhat disappointing to see.

But we can assure you this ESP32 alarm clock created by [Pangodream] is absolutely not one of them. He’s packed an impressive number of features into this unassuming little timepiece, and it’s really an excellent example of how much these boards are capable of without breaking a sweat. From DIY touch sensors to the Android application used to configure the clock over the network, this project is overflowing with neat hardware and software tricks worth taking a closer look at.

Inside the 3D printed case, the clock features a BH150 light sensor, the very popular DHT-11 for detecting temperature and humidity, as well as a ILI9341 2.8 inch LCD for the display. In a particularly clever touch (get it?), [Pangodream] used three coins connected to the digital pins of the ESP32 as capacitive sensors. These allow him to interact with the click just by tapping the top of the case, and saved him the trouble of adding traditional switches or buttons. We might have put some indentations in the top case to make identifying which of the three “buttons” you’re pushing, but we suppose the invisible interface does make things look a little more futuristic.

But if even that is too much physical touching for you, then [Pangodream] has come up with a fairly robust system for controlling and interacting with the clock over the network. It’s not just a convenient way of setting the time, a good number of the clock’s functions can be polled and configured in this manner; everything from the sensitivity of the touch sensors to how many times it will beep when the alarm goes off. To make things easier, he’s even wrapped it all up in a handy Android application for on the go configuration.

If this clock doesn’t offer you the level of over-engineering you require, check out this build that uses no less than five ESP32s to get the job done. Or maybe this one that hooks into NASA’s Deep Space Network.

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Send Smooches Over Skype With The Kiss Interface

This project of [Nathan]’s certainly has a playful straightforwardness about it. His Skype ‘Kiss’ Interface has a simple job: to try to create a more intuitive way to express affection within the limits of using Skype. It all came about from a long distance relationship for which the chat program was the main means of communicating. Seeking a more intuitive and personal means of expressing some basic affection, [Nathan] created a capacitive touch sensor that, when touched with the lips, sends the key combination for either a kissy face emoji or the red lips emoji, depending on the duration.

Capacitive touch sensing allows for triggering the sensor without actually physically touching one’s lips to the electrodes, which [Nathan] did by putting a clear plastic layer over the PCB traces. His board uses an STM32 microcontroller with software handling the USB HID and STM’s TSC (Touch Sensing Controller) functionality. As a result, the board has few components and a simple interface, which was in keeping with the goal of rejecting feature creep and focusing on a simple task.

Clearly the unit works; but how well does it actually fulfill its intended purpose? We don’t know that yet, but we do know that [Nathan] seems to have everything he needs in order to find out. Either way, it’s a fun project that definitely fits the spirit of the Human-Computer Interface Challenge of The Hackaday Prize.

There Are Multiple Ways To Gesture With This Serpentine Sensor

Serpentine is a gesture sensor that’s the equivalent of a membrane potentiometer, flex and stretch sensor, and more.  It’s self-powering and can be used in wearable hacks such as the necklace shown in the banner image though we’re thinking more along the lines of the lanyard for Hackaday conference badges, adding one more level of hackability. It’s a great way to send signals without anyone else knowing you’re doing it and it’s easy to make.

Collecting analog data from Serpentine

Serpentine is the core of a research project by a group of researchers including [fereshteh] of Georgia Tech, Atlanta. The sensor is a tube made of a silicone rubber and PDMS (a silicone elastomer) core with a copper coil wrapped around it, followed by more of the silicone mix, a coil of silver-coated nylon thread, and a final layer of the silicone mix. Full instructions for making it are on their Hackaday.io page.

There are three general interactions you can have with the tube-shaped sensor: radial, longitudinal, and tangential. Doing various combinations of these three results in a surprising variety of gestures such as tap, press, slide, twist, stretch, bend, and rotate. Those gestures result in signals across the copper and silver-coated nylon electrodes. The signals pass through an amplifier circuit which uses WiFi to send them on to a laptop where signal processing distinguishes between the gestures. It recognizes the different ones with around 90% accuracy. The video below demonstrates the training step followed by testing.

Serpentine works as a result of the triboelectric nanogenerator (TENG) phenomenon, a mix of the triboelectric effect and electrostatic induction but fabrics can be made which use other effects too. One example is this fabric keyboard and theremin which works in part using the piezoelectric effect.

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Touch Panels Make This Christmas Tree Interactive

The city of Liverpool, famously known as both the home port of the Titanic and the birthplace of The Beatles, also seems to have a thing for interactive public art installations. Witness this huge interactive Christmas tree that can be played by passersby.

The display in the city’s busy Williamson Square was commissioned by a municipal business group and built by [Adrian McEwen]. The idea was to adorn the 10-meter natural tree with large geometric ornaments covered with Neopixel strips. [Adrian] documents the build process in some detail, including that fact that over 170 meters of WS2812b strips went into the ornaments for the tree. While the strips themselves at IP68 rated, the connections needed when attaching them to the custom-made frames were not, and that had to be overcome with ample application of heat-shrink tubing. OctoWS2811 adapter boards were dangled about the tree to control the lights and connected together with garlands of Ethernet cables. Pressure sensors were used to control the lights when the EMI from the beefy power supplies needed to run everything proved too much for the original touch sensors. After a lot of bench testing and a few long nights working with the city crew to hang the display, passing Liverpudlians can now play the tree and enjoy the Christmas season.

Would you rather a smaller display for your own Christmas tree? This somewhat hyperactive indoor light show might be what you’re looking for.

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Everything’s A Touch Surface With Electrick

Touch screens are great, but big touchscreens are expensive and irregular touchscreens are not easy to make at all. Electrik is a method developed by several researchers at Carnegie Mellon University that makes almost any solid object into a touch surface using tomography. The catch is that a conductive coating — in the form of conductive sheets, 3D plastic, or paint — is necessary. You can see a demonstration and many unique applications in the video below. They’ve even made a touch-sensitive brain out of Jell-O and a touchable snowman out of Play-Doh.

The concept is simple. Multiple electrodes surround the surface. The system injects a current using a pair of electrodes and then senses the output at the other terminals. A finger touch will change the output of several of the electrodes. Upon detection, the system will change the injection electrodes and repeat the sensing. By using multiple electrode pairs and tomography techniques, the system can determine the location of touch and even do rough motion tracking like a low-resolution touch pad mouse.

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