Hedgehog Gesture Sensor Built With Cheap Time-of-Flight Modules

November 2, 2021 by Zoe Skyforest 6 Comments

Time-of-flight sensors used to be expensive obscurities, capable of measuring the travel time of photons themselves and often used for tracking purposes. However, the technology is cheaper now, such that [jean.perardel] has used TOF sensors to build a useful and affordable gesture-tracking system.

The system relies on four VL53L1X time of flight sensors, which have a 16×16 scanning array and communicate over the I2C bus. Controlling the show is an Arduino MKR1010, though the project should be achievable with a range of other microcontrollers, too.

The device is built into a cute hedgehog-like form factor, with an LCD screen acting as the face. It displays facial expressions which show how the system is interpreting and responding to gestures. It gives the project lots of personality, which makes using the system more fun. Gestures from the system can be used to send keystrokes over USB, control relays or servos, or even fire IR signals to control TVs and other hardware.

It actually seems like a useful gesture control interface, one that could become a useful part of a workstation setup. We’ve seen gesture controls put to other uses too, like controlling robot arms. Video after the break.

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Supersonic Baseball Hitting A Gallon Of Mayo Is Great Flow Visualization

November 1, 2021 by Zoe Skyforest 22 Comments

Those of us who enjoy seeing mechanical carnage have been blessed by the rise of video sharing services and high speed cameras. Oftentimes, these slow motion videos are heavy on destruction and light on science. However, this video from [Smarter Every Day] is worth watching, purely for the fluid mechanics at play when a supersonic baseball hits a 1-gallon jar of mayo.

The experiment uses the baseball cannon that [Destin] of [Smarter Every Day] built last year. Ostensibly, the broader aim of the video is to characterize the baseball cannon’s performance. Shots are fired with varying pressures applied to the air tank and vacuum levels applied to the barrel, and the data charted.

However, the real glory starts 18:25 into the video, where a baseball is fired into the gigantic jar of mayo. The jar is vaporized in an instant from the sheer power of the collision, with the mayo becoming a potent-smelling aerosol in a flash.

Amazingly, the slow-motion camera reveals all manner of interesting phenomena. There’s a flash of flame as the ball hits the jar, suggesting compression ignition happened at impact with the jar’s label. A shadow from the shockwave ahead of the ball can be seen in the video, and particles in the cloud of mayo can be seen changing direction as the trailing shock catches up.

The slow-motion footage deserves to be shown in flow-visualization classes, not only because it’s awesome, but because it’s a great demonstration of supersonic flow phenomena. Video after the break.

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Building A Bicycle Dash Cam With Advanced Capabilites

November 1, 2021 by Zoe Skyforest 15 Comments

Riding a bicycle is a wonderful and healthy way to get around. However, just like with any other vehicle on the road, it can be useful to have a camera to record what goes on in traffic. [Richard Audette] built just such a rig.

The original setup relies on a Raspberry Pi 3, which takes a photo every 10 seconds using the attached Pi Camera. It then processes these photos using OpenALPR, which is a piece of software for reading licence plates. Licence plates detected while cycling can be stored on the Raspberry Pi for later, something which could be useful in the event of an accident.

However, [Richard] has developed the concept further since then. The revised dashcam adds blind spot detection for added safety, and uses a Luxonis OAK-D camera which provides stereo depth data and has AI acceleration onboard. It’s paired with a laptop carried in a backpack instead of a Raspberry Pi, and can stream video to a smartphone sitting on the handlebars as a sort of rear-view mirror.

Anyone who has commuted on a bicycle will instantly see the value in work like [Richard]’s. Just avoiding one accident from a car coming from behind would be of huge value, and we’re almost surprised we don’t see more bicycle rear view kits in the wild.

Alternatively, if you just want to scan your surroundings as you ride, consider building a landscape scanner instead. Video after the break.

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Building A Kinetic Sand Art Table

October 31, 2021 by Zoe Skyforest 16 Comments

Many of us have marveled at art installations that feature marbles quietly and ceaselessly tracing out beautiful patterns in sand. [DIY Machines] is here to show us that it’s entirely possible to build one yourself at home!

The basic mechanism is simple enough. The table uses a Cartesian motion platform to move a magnet underneath a table. On top of the table, a metal sphere attached to the magnet moves through craft sand to draw attractive patterns. An Arduino and Raspberry Pi work together to command the stepper motors to create various patterns in the sand.

Low-cost pine is used to build most of the table, with oak used for the attractive bare wooden top. RGB LEDs surround the sand surface in order to light the scene, with options for mad disco lighting or simple white light for a subtler look. Other nice touches include sitting the craft sand atop a layer of faux leather, so the ball moving through the sand doesn’t make annoying crunching sounds as the ball moves.

It’s a great build that focuses on the smaller details like noise that can make a big difference to the final experience. We’ve seen similar projects before, too. Video after the break.
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Dante’s Inferno Arcade Reveals Your True Fate

October 31, 2021 by Zoe Skyforest 6 Comments

Many of us are vaguely familiar with the levels of hell described in Dante’s epic poem from the 14th century, even if we’ve never visited ourselves. It’s natural to wonder in which circle of hell one might end up, but that’s a question that [scubabear’s] arcade build seeks to answer.

The stand-up cabinet was built for The Magic Castle, Hollywood’s exclusive private club for the magic set. The design is loosely inspired by old-fashioned love testers, the sort of which you might have seen in that Simpsons episode. The club has traditionally issued members with unique RFID tags in keychains, which can be used to trigger special objects in the facility. In this case, when a member scans their keychain and places their hand on a handprint, the machine starts up.

The hand is detected by an Adafruit touch sensor board, and the machine begins determining the fate of the member while playing a short musical interlude. Once calculated by the Raspberry Pi within, the user’s name is read out based on the RFID data, and their destiny is read aloud. They’re then given a receipt stating their destination in hell, along with a quote from Dante’s Inferno.

It’s a fun game and one that we’d love to try out if we find ourselves visiting The Magic Castle one spooky day. It’s made all the better by the sheer quality of the cabinet and the associated illustrations from [Jeremy Owen.]

For those keen to do something similar, [scubabear] hasn’t skimped on the details of the construction nor the electronics that make it all work. We’ve seen other great builds too, from the carefully crafted to the glowiest you’ve ever seen. Video after the break.

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A Hackable Keyboard That Even Has Screens

October 30, 2021 by Zoe Skyforest 4 Comments

There are a huge number of available keyboards out in the world these days, catering to all of the plainest and the most advanced desires. However, if you want something that’s just right, sometimes it pays to build your own. [Zach] did just that.

One of the key features of [Zach]’s build is that it diverges away from the Cherry MX switch form factor. The design uses low-profile switches instead, which help with keeping the keyboard low enough to avoid it causing wrist problems. The keyboard also uses IO expanders to hook up all the key switches, helping to reduce the incidence of ghost keys. The board can also be split in half, allowing it to be repurposed as a smaller macropad when desired.

It’s all wrapped up in a cool 3D printed case, and there are even three OLED displays on the right-hand side. They’re soldered to the PCB on special cutouts that allow the displays to flex and trigger tactile switches, acting as giant pressable buttons.

[Zach] does a great job explaining all the nifty engineering decisions he made to cram maximum functionality into the design. We’ve seen some other great DIY ergonomic designs too. Video after the break.

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This Smart Watch Keeps An Eye On Ambient CO2 Levels

October 30, 2021 by Zoe Skyforest 20 Comments

Human respiration takes in oxygen and in turn, we exhale carbon dioxide. Thus, an uptick of carbon dioxide levels around us can indicate we’re in the presence of other humans, and also, perhaps, the pathogens they carry. To explore this phenomenon, [C Scott Ananian] developed a mod for the Watchy open-source smartwatch, which lets it detect carbon dioxide.

The idea behind the build is simple. If you’re around increased CO2 levels, it may be because you’re surrounded by people, and thus more likely to be exposed to COVID-19. To detect CO2, the watch relies on a Sensiron SCD40 or SCD41 sensor. This is read by the Watchy’s ESP32 microcontroller, and results are graphed on the watch’s e-Paper display. The Watchy is also given a nice new aluminum case to fit the additional hardware.

It’s cool having a graph on your wrist of the ambient concentration of CO2, and at the very least, it could make a good talking point next time you’re at a particularly boring party. You’ll also be more than ready to advise other partygoers if the carbon dioxide level is reaching dangerous levels.

We’ve seen similar builds before, which are useful not only for pandemic safety but also for monitoring if you have any leaks from CO2 storage in the house. If you’ve been working on your own ways to track dangerous gases, be sure to drop us a line!