Cutting The Grass With Frickin’ Lasers

September 2, 2022 by Dave Rowntree 29 Comments

We techie types are quite often much more comfortable in front of a keyboard knocking out code, than out in the yard splitting logs for winter, and even the little jobs like cutting the grass are sometimes just too much like hard manual labour for our liking. The obvious solution is a robot mower, but they’re kinda boring, with their low-tech spinning metal blades. What we need is a big frickin’ laser. YouTuber [rctestflight] has been experimenting with using a 40W blue diode laser module to cut the weeds, (Video, embedded below) and it sort of works, albeit in a rather dangerous fashion.

The first test used a fixed assembly, mounting the laser to a camera lens, upon a rotating gear driven by a small stepper motor. An Arduino controls the beam scanning, very slowly, burning the grass in its sights. But with a range limited to around eight feet best case, sitting in one spot just isn’t going to cut it. (sorry) The obvious next step was to mount one of the tested laser modules onto a moveable platform. After tweaking one of his earlier projects — a tracked rover — with a new gearbox design, it could now drive slow enough to be useful for this slow task. The laser was mounted to a simple linear rail slider, with an attempt at a vacuum pickup system to suck up the clippings, removing them from the beam path, and stopping them impeding the cutting efficiency of the laser.

Obviously this vacuum idea didn’t work, and since the contraption takes the best part of a week to cut just one small area, we reckon it would likely be growing faster than that! Still, it must have been fun to build it anyway. It just goes to show that despite the march of technological progress, maybe the boring old spinning blades of old are still the best way to get the job done.

Lawnmowing is clearly one of those jobs we love to hate, and do so with hacks. Here’s a way to prevent your mower sucking up foreign bodies and hurling them at you at ballistic speeds, and for those who really want to be hands off, add RTK-GPS to a robot mower, and just leave it to do the dirty work.

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Magnetic Gearbox Can Go Fast But Not Hard

September 2, 2022 by Danie Conradie 13 Comments

3D printed gearboxes are great for experimental designs, but due to roughness and inaccuracies in the printed surfaces, they can wear quickly and be rather noisy. As a possible alternative, [Resetman] is experimenting with magnetic 3D printed gearboxes that work without physical contact between the rotating wheels, and can also be “geared” for different ratios in some interesting ways.

Naturally, two closely spaced wheels with magnets will interact with each other, with the ratio defined by the number of magnets on each wheel. A much less obvious implementation is a second-order radial flux coaxial magnetic gearbox. It works similar to a normal planetary gearbox, with an outer and inner wheel containing magnets, and an intermediate ring known as a flux modulator, containing equally spaced pieces of ferromagnetic steel metal. In [Resetman] demonstration, the flux modulator is just a 3D printed ring screws around its circumference.

The most obvious disadvantage is of course severely limited torque transfer. [Resetman] could easily accelerate the sun wheel to 12,000 RPM if the flux modulator is accelerated slowly, but any sudden changes in speed would cause it to lose synchronization. Of course, you can consider this a torque-limiting feature for certain use cases. With a bit of testing, he determined the torque limit at a 1:4 ratio was a meager 0.05 Nm. This could be increased by some optimization, for example rearranging the magnets to form Halbach arrays, and reducing the air gaps between the components.

Magnetic gearboxes are nothing new, we’ve featured another demonstrator before, and even did an “Ask Hackaday” on the subject. What would you use these for? Let us know below.

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Hackaday Prize 2022: A Cooler For Your Footwear

September 2, 2022 by Lewin Day 15 Comments

Sweaty feet can be uncomfortable, and the smell generated in one’s shoes isn’t much to admire, either. In an effort to help solve this issue, [Revoxdyna] has created a cooler for one’s feet that should help out in hot conditions.

Modern shoes, particularly sneakers, are often ventilated, but it’s not always enough. This build takes things further, using active cooling. Water is pumped through tubes and into a copper insole which cools the sole of the foot. It’s achieved thanks to a pump assembly that mounts to the rear of the shoe in a 3D printed housing. The water itself is chilled with a thermoelectric cooler, which helps remove heat from the shoe area.

There is some bulk to the design, which would prevent its use in performance applications in its current form. However, we could imagine companies like Nike leaping at the chance to build some very fancy, high-tech shoes along these lines in future. After all, they already managed to create power laces, and this is even cooler again! Pun definitely intended.

This Week’s Hack Chat Sets The Stage For Supercon

September 2, 2022 by Tom Nardi No comments

While the 2020 and 2021 Remoticons were a blast, we all know that virtual events are no substitute for in-person conferences. Which is why we’re so excited to once again invite the Hackaday community to converge on Pasadena in November for a weekend of talks, workshops, and hardware hacking for our sixth Supercon.

To help get the community prepared for the triumphant return of what we very humbly believe to be the greatest hardware hacking conference the world has ever seen, we invited Majenta Strongheart to this week’s Hack Chat to answer the community’s questions about this hotly anticipated event. There’s an incredible number of moving pieces involved in an event like Supercon, and as Head of Design and Partnerships at our parent company SupplyFrame, she’s integral to putting them all together right up until the doors open on November 4th.

The Chat kicked off with a general confirmation that yes, we did receive your talk and/or workshop proposal. It seems several people didn’t receive the intended confirmation message when they sent their information on, but Majenta assured everyone that all of the completed forms were received correctly and are currently under review. If you put in a proposal, you should be notified in the next few weeks about whether or not it was accepted.

With that out of the way, the next big question was the one that so many of you have been wondering: what does the Hackaday Supercon look like in the era of COVID? The truth is, things are still evolving and it’s hard to be sure of anything with two more months to go. But Majenta did confirm that the decision has been made to limit ticket sales compared to previous years so that attendees have a bit more breathing room — literally and figuratively. In addition many of the planned events will be held outdoors, and the talks will be streamed live for anyone who’d rather not sit in the audience.

Majenta also took this opportunity to let everyone know that the volunteer application form for Supercon will be available very soon, and that as usual, those who are willing to help out will get a free ticket in exchange. Speaking of which, if you’d rather pay the gold price, General Admission tickets for the 2022 Supercon are currently on sale.

As you might imagine, Majenta has been exceptionally busy as of late, so we appreciate her taking the time to sit down with us and Chat. If you couldn’t make this live discussion about Supercon, don’t worry. You can send questions, ideas, or comments, to superconference@hackaday.io and we’ll see what we can do.

The Hack Chat is a weekly online chat session hosted by leading experts from all corners of the hardware hacking universe. It’s a great way for hackers connect in a fun and informal way, but if you can’t make it live, these overview posts as well as the transcripts posted to Hackaday.io make sure you don’t miss out.

Robot Brutally Chops But Makes Poor Guacamole

September 2, 2022 by Lewin Day 27 Comments

Making guacamole by hand normally takes [Estefannie] about 9 minutes. Given her insatiable appetite for the delicious condiment, she spends a lot of time whipping it up in the kitchen at home. Thus, it’s a task ripe for automation, and she set about building a robot to do the job instead.

The robot starts by chopping ingredients like tomato, onion, and avocado with a knife that swivels to cover the entire chopping board surface. Once chopped, a sweeping blade pushes the ingredients into a bowl to form the guacamole.

Initial tests were messy, and ingredients were chopped a little inconsistently. Later work involved reprogramming the machine to chop ingredients separately, rather than all at once, which did improve the quality of the guacamole significantly. However, fundamentally, it wasn’t making good guac, so much as it was making a very chunky salad. It simply couldn’t do all the complicated jobs required to make a smooth, delicious dip.

[Estefannie] elected to instead let it live out its life as a mighty chopper, showing off its prowess by having it attack candy, cake, watermelon, and chocolate, which was pretty fun to watch. It bears noting that if you’re building a robot that swings a blade around, you need to be very careful. If you’re looking for something a bit safer, perhaps a Taco Bot is in your future.

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This Week In Security: Malicious Clipboards, Snakes On A Domain, And Binary Golf

September 2, 2022 by Jonathan Bennett 4 Comments

There’s a bit of a panic regarding Chromium, Google Chrome, the system clipboard, and of all things, Google Doodles on the New Tab Page. It’s all about Chromium issue 1334203, “NewTabPageDoodleShareDialogFocusTest.All test fails when user gesture is enforced”. You see, Chromium has quite a large regression test suite, and Google engineers want to ensure that the Google Doodles always work. A security feature added to the clipboard handling API happened to break a Doodles test, so to fix the Doodle, the security feature was partially reverted. The now-missing feature? Requiring user interaction before a page can read or write to the clipboard.

Now you understand why there’s been a bit of a panic — yes, that sounds really bad. Pages arbitrarily reading from your clipboard is downright malicious and dangerous. And if no interaction is required, then any page can do so, right? No, not quite. So, Chrome has a set of protections, that there are certain things that a page cannot do if the user has not interacted with the page. You might see this at play in Discord when trying to refresh a page containing a video call. “Click anywhere on this page to enable video.” It’s intended to prevent annoying auto-play videos and other irritating page behavior. And most importantly, it’s *not* the only protection against a page reading your clipboard contents. See for yourself. Reading the clipboard is a site permission, just like accessing your camera or mic.

Now it’s true that a site could potentially *write* to the clipboard, and use this to try to be malicious. For example, writing rm -rf / on a site that claims to be showing off Linux command line tips. But that’s always been the case. It’s why you should always paste into a simple text editor, and not straight into the console from a site. So, really, no panic is necessary. The Chromium devs tried to roll out a slightly more aggressive security measure, and found it broke something unrelated, so partially rolled it back. The sky is not falling.
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Truthsayer Uses Facial Recognition To See If You’re Telling The Truth

September 2, 2022 by Dan Maloney 18 Comments

It’s hard to watch [Mark Zuckerberg]’s 2018 Congressional testimony and not come to the conclusion that he is, at a minimum, quite a bit different than the average person. Of course, having built a multibillion-dollar company that drastically changed everything about the way people communicate is pretty solid evidence of that, but the footage at least made a fun test case for this AI truth-detecting algorithm.

Now, we’re not saying that anyone in these videos was lying, and neither is [Fletcher Heisler]. His algorithm, which analyzes video of a person and uses machine vision to pick up cues that might be associated with the stress of untruthfulness, is far from perfect. But as the first video below shows, it is a lot of fun to see it at work. The idea is to capture data like pulse rate, gaze direction, blink rate, mouth posture, and even hand position and use them as a proxy for lying. The second video, from [Fletcher]’s recent DEFCON talk, has much more detail.

The key to all this is finding human faces in a video — a task that seemed to fail suspiciously frequently when [Zuck] was on camera — using OpenCV and MediaPipe’s Face Mesh. The subject’s pulse is detected by watching for subtle changes in the color of a subject’s cheeks as blood flows through them, which we’ve heard about plenty of times but never before seen presented so clearly and executed so simply. Gaze direction, blinking, and lip compression are fairly easy to detect too. [Fletcher] also threw in the FER library for facial expression recognition, to get an idea of the subject’s mood. Together, these cues form a rough estimate of the subject’s truthiness, which [Fletcher] is quick to point out is just for entertainment purposes and totally shouldn’t be used on your colleagues on the next Zoom call.

Does [Fletcher]’s facial mesh look familiar? It should, since we once watched him twitch his way through a coding interview.

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