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Hackaday Links: May 15, 2022

It may be blurry and blotchy, but it’s ours. The first images of the supermassive black hole at the center of the Milky Way galaxy were revealed this week, and they caused quite a stir. You may recall the first images of the supermassive black hole at the center of the M87 galaxy from a couple of years ago: spectacular images that captured exactly what all the theories said a black hole should look like, or more precisely, what the accretion disk and event horizon should look like, since black holes themselves aren’t much to look at. That black hole, dubbed M87*, is over 55 million light-years away, but is so huge and so active that it was relatively easy to image. The black hole at the center of our own galaxy, Sagittarius A*, is comparatively tiny — its event horizon would fit inside the orbit of Mercury — a much closer at only 26,000 light-years or so. But, our black hole is much less active and obscured by dust, so imaging it was far more difficult. It’s a stunning technical achievement, and the images are certainly worth checking out.

Another one from the “Why didn’t I think of that?” files — contactless haptic feedback using the mouth is now a thing. This comes from the Future Interfaces Group at Carnegie-Mellon and is intended to provide an alternative to what ends up being about the only practical haptic device for VR and AR applications — vibrations from off-balance motors. Instead, this uses an array of ultrasonic transducers positioned on a VR visor and directed at the user’s mouth. By properly driving the array, pressure waves can be directed at the lips, teeth, and tongue of the wearer, providing feedback for in-world events. The mock game demonstrated in the video below is a little creepy — not sure how many people enjoyed the feeling of cobwebs brushing against the face or the splatter of spider guts in the mouth. Still, it’s a pretty cool idea, and we’d like to see how far it can go.

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Haptic Smart Knob Does Several Jobs

A knob is a knob, a switch is a switch, and that’s that, right? And what about those knobs that have detents, set in stone at the time of manufacturing? Oh, and those knobs that let you jog left to right and then snap back to center — that can’t be modified…right? Well, you likely know where this is going, and in the video below the break, [scottbez1] shows off a new open source haptic input knob that can be all of these things with just some configuration changes!

The list of possibilities is long: virtual snap points, virtual spring loading, virtual detents, virtual end points. It’s a virtual smörgåsbord of configuration options that make this haptic smart knob a one stop shop for all of your knob needs. This is all possible because the knob contains a high resolution magnetic encoder chip that has a single degree resolution. The sensor is coupled, through software, to a brushless DC motor. The round LCD gives visual feedback as well.

As [Myself] on the Hackaday Discord channel noted, having configurable spacing and strength for detents, springs, and stops, is nothing short of incredible. Being able to reconfigure the knob at-will means that it can become context sensitive. It’s wonderfully unique and it’s open source, so you can make your own with the information available at GitHub.

And according to its creator, the only thing the Haptic Smart Knob can’t do is do your taxes or blend your margarita. Well, it’s open source, so perhaps some of our more enterprising readers can submit just the right pull request.

This isn’t Hackaday’s first Motorized Volume Knob feature, but it might be one of the neatest we have seen so far. Thanks to [mattvenn] on the Hackaday Discord server for the great tip!

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Low Cost Haptic VR Gloves Work With Hacked Steam Games

[Lucas VRTech] has made some significant progress with building force-feedback type haptic gloves for use with Steam VR games. The idea is pretty straightforward: the end of the finger is attached to a cable, which is pulled from inside a sprung-loaded spool; the kind used for hanging ID cards on.

The spool body can rotate, but a peg protruding from it engages with the arm of a co-located servo motor. This produces a programmable stop position. But it is a hard stop, and it is not possible with the current hardware to detect precisely when the stop is reached, nor is it possible to control the force it is pushing with. Such features are not difficult to achieve, its just a matter of a little more development with some custom mechatronics.

The current prototype has a focus on cost, which is great as an early development platform. By leveraging 3D printing and off-the-shelf parts that are easy to source; just a handful (chuckle!) of potentiometers, some servo motors and one from any number of ESP32 dev boards and you’re done. The real work is on the software side of things, as the games themselves need to be modified to play ball with the VR glove hardware. This has been achieved with a combination of a custom steam driver they call OpenGloves, and community developed per-game mods. A few titles are available to test right now, so this is definitely something some of us could build in a weekend and get involved with.

The hardware source for the glove mount and per-finger units can be found on the project GitHub, together with the ESP32 source for Arduino.

For some other haptic-related inspiration, here’s a force-feedback mouse, and for a more hand-off feedback, we have a wind-blaster project.

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Haptic Feedback “Rifle” Lets You Take Aim In VR

There was a time when virtual reality seemed like it would remain in the realm of science fiction at least for the foreseeable future. Then we were blessed with products like the Power Glove and Virtual Boy which seemed to make it more of a reality, if not a clunky and limited one. Now, though, virtual reality is taking more of a center stage as the technology for it improves and more and more games are released. We can see no greater proof of this than the fact that some gamers are building their own custom controllers to interact with the virtual world in more meaningful ways, like this game controller specifically built for first-person shooter games.

The controller is based on an airsoft gun but completely lacks the ability to fire a projectile, instead using the gun as a base for building the controller. In fact, the gun’s operation is effectively reversed in order to immerse the player into the game by using haptic feedback provided by pressurized air. The air is pumped in to what would be the front of the barrel and is discharged through the receiver when a trigger pull is detected in order to generate a recoil effect. The controller includes plenty of other features as well, including the ability to reload ammunition, change the firing mode, and track motion thanks to its pair of integrated Oculus controllers.

All of the parts for this controller are either 3D printed or readily available off-the-shelf, making this an ideal platform for customization and improvement. There’s also a demo game available from Unity which allows for a pretty easy setup for testing. While the controller looks like an excellent way to enjoy an FPS virtual reality experience, if you’re looking for a more general-purpose controller we are also starting to see a lot of development on that end as well.

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The Word Clock You Can Feel

By this point, pretty much everyone has come across a word clock project, if not built one themselves. There’s just an appeal to looking at a clock and seeing the time in a more human form than mere digits on a face. But there are senses beyond sight. Have you ever heard a word clock? Have you ever felt a word clock? These are questions to which Hackaday’s own [Moritz Sivers] can now answer yes, because he’s gone through the extreme learning process involved in designing and building a haptic word clock driven with the power of magnets.

Individual letters of the display are actuated by a matrix of magnetic coils on custom PCBs. These work in a vaguely similar fashion to LED matrices, except they generate magnetic fields that can push or pull on a magnet instead of generating light. As such, there are a variety of different challenges to be tackled: from coil design, to driving the increased power consumption, to even considering how coils interact with their neighbors. Inspired by research on other haptic displays, [Moritz] used ferrous foil to make the magnets latch into place. This way, each letter will stay in its forward or back position without powering the coil to hold it there. Plus the letter remains more stable while nearby coils are activated.

Part of the fun of “ubiquitous” projects like word clocks is seeing how creative hackers can get to make their own creations stand out. Whether it’s a miniaturized version of classic designs or something simple and clean, we  love to see them all. Unsurprisingly, [Moritz] himself has impressed us with his unique take on word clocks in the past. (Editor’s note: that’s nothing compared to his cloud chambers!)

Check out the video below to see this display’s actuation in action. We’re absolutely in love with the satisfying *click* the magnets make as they latch into place.

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