Simple Sensor Provides Detailed Motion Capture for VR Hands

Consider the complexity of the appendages sitting at the end of your arms. The human hands contain over a quarter of the entire complement of bones in the body, use dozens of muscles both in the hand itself and extending up the forearm, and are capable of almost infinite variance in the movements they can create. They are exquisite machines.

And yet when it comes to virtual reality, most simulations treat the hands like inert blobs. That may be partly due to their complexity; doing motion capture from so many joints can be computationally challenging. But this pressure-sensitive hand motion capture rig aims to change that. The product of an undergraduate project by [Leslie], [Hunter], and [Matthew], the idea was to provide an economical and effective way to capture gestures for virtual reality simulators, which generally focus on capturing large motions from the whole body.

The sensor consists of a sandwich of polyurethane foam with strain gauge sensors embedded within. The user slips his or her hand into the foam and rests the fingers on the sensors. A Teensy and twenty lines of code translate finger motions within the sandwich into five axes of joystick movement, which is then sent to Unreal Engine, where finger motions were translated to a 3D-model of a hand to play a VR game of “Rock, Paper, Scissors.”

[Leslie] and her colleagues have a way to go on this; testers complained that the flat hand posture was unnatural, and that the foam heated things up quickly. Maybe something more along the lines of these gesture-capturing gloves would work?

Build Your Own Anechoic Chamber

For professional-level sound recording, you’ll need professional-level equipment. Microphones and mixing gear are the obvious necessities, as well as a good computer with the right software on it. But once you have those things covered, you’ll also need a place to record. Without a good acoustic space, you’ll have all kinds of reflections and artefacts in your sound recordings, and if you can’t rent a studio you can always build your anechoic chamber.

While it is possible to carpet the walls of a room or randomly glue egg crate foam to your walls, [Tech Ingredients] tests some homemade panels of various shapes, sizes, and materials against commercially available solutions. To do this he uses a special enclosed speaker pointed at the material, and a microphone to measure the sound reflections. The tests show promising results for the homemade acoustic-absorbing panels, at a fraction of the cost of ready-made panels.

From there, we are shown how to make and assemble these panels in order to get the best performance from them. When dealing with acoustics, even the glue used to hold everything together can change the properties of the materials. We also see a few other cost saving methods in construction that can help when building the panels themselves as well. And, while this build focuses on acoustic anechoic chambers, don’t forget that there are anechoic chambers for electromagnetic radiation that use the same principles as well.

Thanks to [jafinch78] for the tip!

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3D Printed Upgrade for Cheap Foam Glider

We know you’ve seen them: the big foam gliders that are a summertime staple of seemingly every big box retailer and dollar store in the world. They may be made by different companies or have slight cosmetic differences, but they all adhere to the basic formula: a long plastic bag containing the single-piece fuselage and two removable wings and a tail. Rip open the bag, jam the wings into the fuselage, and go see if you can’t get that thing stuck on a roof someplace.

But after you toss it around a few times, things start to get a little stale. Those of us in the Hackaday Collective who still retain memories of our childhood may even recall attempting to augment the glider with some strategically attached bottle rockets. But [Timothy Wright] has done considerably better than that. With the addition of a 3D printed “backpack”, he managed to add not only a motor to one of these foam fliers but an RC receiver and servos to move the control surfaces. The end result is a cheap and surprisingly capable RC plane with relatively little work required.

[Timothy] certainly isn’t claiming to be the first person to slap a motor on a foam glider to wring a bit more fun out of it, but his approach is very slick and of course has the added bonus of being available for other grownup kids to try thanks to the Creative Commons license he released the designs under. He mentions that variations in the different gliders might cause some compatibility issues, but with the generous application of some zip ties and tape, it should be good to go.

This particular hunk of foam might not set any altitude or distance records, and it certainly won’t be carrying you aloft, but it’s a pretty approachable summer project if you’ve got some RC gear laying around.

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Zen and the Art of Foam Core

Some of our pastimes are so deeply meditative that we lose ourselves for hours. Our hands seem to perform every step, and sequence like a pianist might recite her favorite song. If [Eric Strebel]’s voice and videos are any indications, working with foam core can have that effect.

Foam core is a staple of art stores, hobby stores, and office supply stores. It comes in different colors, but the universal trait is a sheet of foam sandwiched between a couple of layers of paper. This composition makes a versatile material which [Eric] demonstrates well in his advanced tutorial making a compound surface and later on a speaker mockup.

After the break, you can catch a couple of beginner tutorials which explain the differences between a slapdash foam core model, and one which will draw appreciation. Proper tools and thoughtful planning might be the biggest takeaways from the first two videos unless you count the Zen narration. The advanced videos, linked above, show some ingenious ways to use foam core like offset scoring, adjustable super-structures, and paper transfers.

Each video is less than ten minutes long, so if you just started your coffee break, you can complete a video right now. Or look at another 2D material turned into amazingness with a papercraft strandbeest, then step up your game with another look at vinyl cutters.
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Printing Without Supports!

If print supports have ever caused you grief, know that there’s an alternate printing method in the works. First: get yourself a vat of industrial gel in which to print.

Rapid Liquid Printing(RLP) is being developed in collaboration by Michigan-based company [Steelcase] and [Skylar Tibbits’] Self Assembly Lab at MIT. RLP is touting advantages over traditional 3D printing technology such as reduced print times, a higher quality print, and enabling larger scale prints — all without supports!

Working with rubber, plastic, or foam, the printing material is injected by nozzle into a basin of industrial gel. That gel suspends the print throughout the process without bonding to it and the finished product is simply lifted out of the gel and rinsed off. Shown off at the Design Miami event earlier this month, onlookers could pick up finished lampshades and tote bags after mere minutes.

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Things Learned From Hot Wire Cutting a Droid’s Body

One of [Bithead]’s passions is making Star Wars droids, and in the process of building the outer shell for one of them he decided to use hot wire foam cutting and make his own tools. Having the necessary parts on hand and having seen some YouTube videos demonstrating the technique, [Bithead] dove right in. Things didn’t go exactly to plan but happily he decided to share what did and didn’t work, and in the end the results were serviceable.

[Bithead] built two hot wire cutters with nichrome wire. The first was small, but the second was larger and incorporated some design refinements. He also got an important safety reminder when he first powered on with his power supply turned up too high; the wire instantly turned red and snapped with an audible bang. He belatedly realized he was foolishly wearing neither gloves nor eye protection.

When it came to use his self-made tools, one of the biggest discoveries was that not all foam is equal in the eyes of a hot wire cutter. This is one of those things that’s common knowledge to experienced people, but isn’t necessarily obvious to a newcomer. A hot wire cutter that made clean and effortless cuts in styrofoam did no such thing with the foam he was using to cast his droid’s outer shell. Still, he powered through it and got serviceable results. [Bithead]’s blog post may not have anything new to people who have worked with foam and hot wire cutters before, but if you’re new to such things you can use it to learn from his experiences. And speaking of improving experiences, [Bithead] most recently snazzed up the presentation of his R2-D2 build by getting tricky with how he hides his remote control.

Hackaday Prize Entry: Arduino Splash Resistant Toilet Foamer

There are some universal human experiences we don’t talk about much, at least not in public. One of them you’ll have in your own house, and such is our reluctance to talk about it, we’ve surrounded it in a fog of euphemisms and slang words. Your toilet, lavatory, john, dunny, khazi, bog, or whatever you call it, is part of your everyday life.

For his Hackaday Prize entry, [VijeMiller] tackles his smallest room head-on. You see, for him, the chief horror of the experience lies with the dreaded splashback. Yes, a bit of projectile power dumping leaves the old rump a little on the damp side. So he’s tackled the problem with some maker ingenuity and installed an Arduino-controlled foam generator that injects a mixture of soap and glycerin to fill the bowl with a splash-damping load of foam. Rearward inundation avoided.

The parts list reveals that the foam is generated by a fish tank aerator, triggered by a relay which is driven by an Arduino Uno through a power transistor. A solenoid valve controls the flow, and a lot of vinyl tubing hooks it all together. There is an HC/06 Bluetooth module with an app to control the device from a phone, though while he’s posted some Arduino code there is no link to the app. There are several pictures, including a cheeky placement of a Jolly Wrencher, and a shot of what we can only surmise is a text, as foam overflows all over the bathroom. And he’s put up the video we’ve placed below the break, for a humorous demonstration of the device in action.

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