Blinks Are Useful In VR, But Triggering Blinks Is Tricky

April 9, 2023 by Donald Papp 8 Comments

In VR, a blink can be a window of opportunity to improve the user’s experience. We’ll explain how in a moment, but blinks are tough to capitalize on because they are unpredictable and don’t last very long. That’s why researchers spent time figuring out how to induce eye blinks on demand in VR (video) and the details are available in a full PDF report. Turns out there are some novel, VR-based ways to reliably induce blinks. If an application can induce them, it makes it easier to use them to fudge details in helpful ways.

It turns out that humans experience a form of change blindness during blinks, and this can be used to sneak small changes into a scene in useful ways. Two examples are hand redirection (HR), and redirected walking (RDW). Both are ways to subtly break the implicit one-to-one mapping of physical and virtual motions. Redirected walking can nudge a user to stay inside a physical boundary without realizing it, leading the user to feel the area is larger than it actually is. Hand redirection can be used to improve haptics and ergonomics. For example, VR experiences that use physical controls (like a steering wheel in a driving simulator, or maybe a starship simulator project like this one) rely on physical and virtual controls overlapping each other perfectly. Hand redirection can improve the process by covering up mismatches in a way that is imperceptible to the user.

There are several known ways to induce a blink reflex, but it turns out that one novel method is particularly suited to implementing in VR: triggering the menace reflex by simulating a fast-approaching object. In VR, a small shadow appears in the field of view and rapidly seems to approach one’s eyes. This very brief event is hardly noticeable, yet reliably triggers a blink. There are other approaches as well such as flashes, sudden noise, or simulating the gradual blurring of vision, but to be useful a method must be unobtrusive and reliable.

We’ve already seen saccadic movement of the eyes used to implement redirected walking, but it turns out that leveraging eye blinks allows for even larger adjustments and changes to go unnoticed by the user. Who knew blinks could be so useful to exploit?

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Arc Overhangs In PrusaSlicer Are A Simple Script Away

February 28, 2023 by Donald Papp 21 Comments

Interested in the new hotness of printing previously-impossible overhangs? You can now integrate Arc Overhangs into PrusaSlicer and give it a shot for yourself. Arc overhangs is a method of laying filament into a pattern of blossoming concentric rings instead of stringing filament bridges over empty space (or over supports).

These arcs are remarkably stable, and result in the ability to print overhangs that need to be seen to be believed. We covered this clever technique in the past and there are now two ways for the curious hacker to try it out with a minimum of hassle: either run the Python script on a G-code file via the command line, or integrate the functionality into PrusaSlicer directly by adding it as an automatic post-processing script. The project’s GitHub repository has directions for both methods.

Here’s how it works: the script looks for layers with a “bridge infill” tag (which PrusaSlicer helpfully creates) and replaces that G-code with that for arc overhangs. It is still a work in progress, so keep a few things in mind for best results. Arc overhangs generally work best when the extruded plastic cools as fast as possible. So it is recommended to extrude at the lowest reliable temperature, slowly, and with maximum cooling. It’s not fast, but it’s said to be faster than wrestling with supports and their removal.

A few things could use improvement. Currently the biggest issue is warping of the arc overhangs when new layers get printed on top of them. Do you have a solution or suggestion? Don’t keep it to yourself; discuss in the comments, or consider getting involved in the project.

Rubber Bands And O-Rings Give 3D Prints Some Stretch

February 26, 2023 by Donald Papp 9 Comments

Sometimes it would be helpful if a 3D printed object could stretch & bend. Flexible filament like TPU is one option, but [NagyBig] designed a simple bracelet to ask: how about embedding rubber bands or o-rings into the print itself?

Embedding objects into prints usually involves hardware like fasteners or magnets, but this is the first one (we can think of) that uses rubber bands. Though we have seen rubber bracelets running on printed wheels, and o-rings used to provide tension on a tool holder.

The end result is slightly reminiscent of embedding 3D printed shapes into tulle in order to create fantastic, armor-like flexible creations. But using rubber bands means the result is stretchy and compliant to a degree we haven’t previously seen. Keep it in mind the next time you’re trying to solve a tricky design problem; an embedded o-ring or rubber band might just do the trick.

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Teaching A Robot To Hallucinate

February 26, 2023 by Donald Papp 8 Comments

Training robots to execute tasks in the real world requires data — the more, the better. The problem is that creating these datasets takes a lot of time and effort, and methods don’t scale well. That’s where Robot Learning with Semantically Imagined Experience (ROSIE) comes in.

The basic concept is straightforward: enhance training data with hallucinated elements to change details, add variations, or introduce novel distractions. Studies show a robot additionally trained on this data performs tasks better than one without.

This robot is able to deposit an object into a metal sink it has never seen before, thanks to hallucinating a sink in place of an open drawer in its original training data.

Suppose one has a dataset consisting of a robot arm picking up a coke can and placing it into an orange lunchbox. That training data is used to teach the arm how to do the task. But in the real world, maybe there is distracting clutter on the countertop. Or, the lunchbox in the training data was empty, but the one on the counter right now already has a sandwich inside it. The further a real-world task differs from the training dataset, the less capable and accurate the robot becomes.

ROSIE aims to alleviate this problem by using image diffusion models (such as Imagen) to enhance the training data in targeted and direct ways. In one example, a robot has been trained to deposit an object into a drawer. ROSIE augments this training by inpainting the drawer in the training data, replacing it with a metal sink. A robot trained on both datasets competently performs the task of placing an object into a metal sink, despite the fact that a sink never actually appears in the original training data, nor has the robot ever seen this particular real-world sink. A robot without the benefit of ROSIE fails the task.

Here is a link to the team’s paper, and embedded below is a video demonstrating ROSIE both in concept and in action. This is also in a way a bit reminiscent of a plug-in we recently saw for Blender, which uses an AI image generator to texture entire 3D scenes with a simple text prompt.

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Sneaky Clock Displays Wrong Time If It Catches You Looking

February 23, 2023 by Donald Papp 20 Comments

We have a soft spot for devices that subvert purpose and expectation, and that definitely sums up [Guy Dupont]’s Clock That Is Wrong. It knows the correct time, but whether or not it displays the correct time is another story. That’s because nestled just above the 7-segment display is a person sensor module, and when it detects that a person is looking towards it, the clock will display an incorrect time, therefore self-defeating both the purpose and primary use case of a clock in one stroke.

The person sensor is a tiny board with tiny camera that constantly does its best to determine whether a person is in view, and whether they are looking towards the sensor. It’s a good fit for a project like this, and it means that one can look at the clock from an oblique angle (meaning one is out of view of the sensor) and see the correct time. But once one moves in front of it, the time changes. You can watch a brief video of it in action in this Twitter thread.

One interesting bit is that [Guy] uses an ESP32-based board to drive everything, but had some reservations about making a clock without an RTC. However, he found that simply syncing time over the network every 10 minutes or so using the board’s built-in WiFi was perfectly serviceable, at least for a device like this.

This reminds us a little of other clocks with subtly subversive elements, like the Vetinari Clock which keeps overall accurate time despite irregularly drifting in and out of sync. Intrigued by such ideas? You’re not alone, because there are even DIY hobby options for non-standard clock movements. Adding the ability to detect when someone is looking directly at such a device opens up possibilities, so keep it in mind if it’s time for a weekend project.

Watch Sony Engineers Tear Down Sony’s VR Hardware

February 19, 2023 by Donald Papp 22 Comments

Teardowns are great because they let us peek not only at a product’s components, but also gain insight into the design decisions and implementations of hardware. For teardowns, we’re used to waiting until enthusiasts and enterprising hackers create them, so it came as a bit of a surprise to see Sony themselves share detailed teardowns of the new PlayStation VR2 hardware. (If you prefer the direct video links, Engineer [Takamasa Araki] shows off the headset, and [Takeshi Igarashi] does the same for the controllers.)

The “adaptive trigger” module responsible for the unique feedback.

One particularly intriguing detail is the custom tool [Araki] uses to hold the headset at various stages of the disassembly, which is visible in the picture above. It looks 3D-printed and carefully designed, and while we’re not sure what it’s made from, it does have a strong resemblance to certain high-temperature SLA resins. Those cure into hard, glassy, off-yellow translucent prints like what we see here.

As for the controller, we get a good look at a deeply interesting assembly Sony calls their “adaptive trigger”. What’s so clever about it? Not only can it cause the user to feel a variable amount of resistance when pulling the trigger, it can even actively push back against one’s finger, and the way it works is simple and effective. It is pretty much the same as what is in the PS5 controller, so to find out all about how it works, check out our PS5 controller teardown coverage.

The headset and controller teardown videos are embedded just below. Did anything in them catch your interest? Know of any other companies doing their own teardowns? Let us know in the comments!

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Tiny PCB Banishes Soldering Fumes, Automatically

February 19, 2023 by Donald Papp 28 Comments

A fan to remove fumes is a handy thing to have when soldering, even better is a fan furnished with a filter. Better still is a fan that activates only when the iron is in use, turning off when the iron is in its stand. Now that’s handy!

[Petteri Aimonen] made exactly such a device when he noticed his JBC BT-2BWA soldering station could detect when the iron is removed from its stand, and indicate its operating mode via status LEDs. Broadly speaking, when the iron is removed from its cradle the green “in use” LED is on. By turning the fan on whenever that LED is lit (and turning it off when it becomes unlit), fume extraction gets a little more elegant and efficient.

Instead of tapping directly into the soldering station’s hardware to detect the LED’s state, [Petteri] went for a completely noninvasive solution that made good use of a few spare parts and a small bit of copper-clad board. The PCB is nothing more than piece of copper-clad board with lands scratched out with a hobby knife.

This tiny board sits atop the soldering station, parking a photodiode directly above the “in use” LED. The circuit is a simple comparator whose output controls fan power via a MOSFET, and a top-facing LED provides as a duplicate “in use” indicator, since the original is hidden under the tiny board.

Even for one-off designs like this, creating a PCB layout in an EDA program like KiCad is still worth doing because one can use it to scratch out lands on a copper-clad board, a technique with similarities to Manhattan-style circuit construction.