Hackaday Links: October 1, 2023

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We’ve devoted a fair amount of virtual ink here to casting shade at self-driving vehicles, especially lately with all the robo-taxi fiascos that seem to keep cropping up in cities serving as testbeds. It’s hard not to, especially when an entire fleet of taxis seems to spontaneously congregate at a single point, or all it takes to create gridlock is a couple of traffic cones. We know that these are essentially beta tests whose whole point is to find and fix points of failure before widespread deployment, and that any failure is likely to be very public and very costly. But there’s someone else in the self-driving vehicle business with way, WAY more to lose if something goes wrong but still seems to be nailing it every day. Of course, we’re talking about NASA and the Perseverance rover, which just completed a record drive across Jezero crater on autopilot. The 759-meter jaunt was completely planned by the onboard AutoNav system, which used the rover’s cameras and sensors to pick its way through a boulder-strewn field. Of course, the trip took six sols to complete, which probably would result in negative reviews for a robo-taxi on Earth, and then there’s the whole thing about NASA having a much bigger pot of money to draw from than any start-up could ever dream of. Still, it’d be nice to see some of the tech on Perseverance filtering down to Earth.

Another hobby horse we frequently mount in this space is the increasing number of humanoid (and animal-oid) robots. Most of the time we make a “Black Mirror” reference or drop an “our robot overlords” joke into the mix, but in a lot of ways that’s just our way of whistling past the graveyard. While anthropomorphic platforms don’t make a lot of sense in most robotic applications, our body plan really does solve a lot of locomotion and associated problems elegantly, so it makes sense to explore it. Still, we have to confess to being a bit surprised to hear that Agility Robotics is building a factory capable of turning out 10,000 of its Digit humanoid robots per year. Creepy backward knees notwithstanding, Digit is a pretty reasonable design for working alongside humans; it’s not overly large or fast, but can still carry loads up to 16 kg and work for 16 hours between charges. When we first spotted this story, we wondered what kind of market would be able to absorb 10,000 Digits a year, but when you’re talking about putting two full-time equivalents into a package that won’t call in sick, won’t get repetitive stress injuries, and won’t unionize — probably — now we’re wondering if Agility is maybe underestimating things a bit.

Back in the days before Reddit became intolerable, we used to love perusing the r/DataIsBeautiful subreddit. This plot of all the objects in the universe seems like it would be the perfect fit over there because it’s one of those visualizations that just keeps on delivering. It takes some time to unwrap, but it’s basically a log-log graph of the physical radius of an object versus its mass. It covers the range from subatomic particles to galactic superclusters, and even includes a couple of “here be monsters” regions where our understanding of physics breaks down — the authors of the original paper cheekily call these “unphysical regions.” If we’re reading the chart right, the smallest possible object in the universe is an “instanton,” an adorable black hole about 10-32 cm in radius with a mass of about a milligram. Also lying along the line on the chart that charts all the black holes is the Hubble radius, which is the size of our universe. This raises the possibility that our universe is a black hole, but the authors dismiss that because physics.

A public service announcement for our US-based readers: don’t forget the nationwide test of the Emergency Alert System (EAS) and the Wireless Emergency Alerts (WEA) scheduled for this coming Wednesday, October 4, at around 2:20 PM Eastern time. Pretty much every device you own will be blipping and beeping for about a minute, so don’t panic — there’ll be plenty of time to do that later.

Happy belated birthday to the oldest US amateur radio operator, Oscar Norris (W4OXH), who turned 106 this week. We didn’t feel like paying for access to the Gaston Gazette to learn more about Oscar, but a little poking around reveals that he’s been an active ham for over 70 years and seemed to be on the air as late as last November. His license is good until 2028, meaning he still has plenty of time to catch up to the oldest known US ham, Cliff Kayhart (W4KKP), who was 109 years old when he went “silent key” back in 2020.

And finally, if you’re a welder or just pretend to be one like us, you might find these super slo-mo shots of welding as fascinating as we did. To create these fantastic shots, TimWelds set up a Chronos camera and a special lighting rig that captures all the action in the weld pool, the spot where the heat of the arc turns metal into liquid. It’s where all the action is in welding, and controlling what’s going on there is critical to weld quality. He shows TIG, MIG, and stick welding in a variety of metals. For our money, AC TIG on aluminum makes for the most interesting presentation; the cleaning action from the polarity reversal is like a little lightning storm. Watching the hydrodynamics of the pool under pulsed DC TIG is pretty cool, too. And it’s not just pretty pictures, either; understanding what happens to the pool on such a fine level of detail really brings home the finer points, like where to add your filler metal and what really happens when you dip your electrode.

13 thoughts on “Hackaday Links: October 1, 2023

  1. Just a note that for anyone interested in how Perseverance is going, I highly recommend checking out Dr Steve Ruff aka ‘Mars Guy’ on Youtube. His videos are short, informative, technical and he is I believe an actual Mars geologist, so he knows his stuff.

  2. Having worked as a specialist welder in Korea for over 3 years I find that video interesting but not very surprising. We were all watching this stuff through our masks daily and we had to know the process by heart for stuff we built to actually work and not fall apart.

  3. i think were going about self driving vehicles all wrong. do what the do with instrument landings in aircraft. those planes only keep the pilot on as a formality. what you do is install guidance hardware in all the traffic lights. such that self driving vehicles can ride the beam and thus only have to concern themselves with collision avoidance. think of it as a virtual rail system.

    1. Just because they don’t always have a hand on the stick, you think they’re not doing anything? They’re operating a bunch of technology most of the time instead of directly operating conventional controls, but even the easy landings are only easy because two skilled people are focusing and paying close attention to a lot of information while telling the plane what to do and being ready to take over if something doesn’t happen the right way.

    1. It’s actually 10^-35 m – it’s just the Planck length. But astronomers tend to use “cm” for units because they’re lazy: pre-1900, most scientists used cgs (centimeter/gram/second) type units: however, those can’t be rationalized with standard engineering units, so most physicists/engineers/etc. formalized MKS (meter/kilogram/second).

      The argument you see online is usually “oh, EM equations in cgs simplify, that’s why they use them” but really the reason is that astronomers don’t usually *work* with EM units outside of magnetic fields, and the cgs unit of magnetic field is a gauss, and lots of astronomical magnetic fields *are* roughly gauss scale. So not only was their no motivation to change (they didn’t care if their idea of currents didn’t match up with engineers) there was a convenience factor at play, too.

      Incidentally, the “instanton” bit is just hand-wavy – the Planck length just comes from combining a few units. It’s not like, a hard limit or anything. None of that’s intended to be exact.

  4. Not to dunk on NASA but making a helicopter that can avoid crashing into the ground or landing on lumpy bits is a slightly easier problem than making a car that can navigate public roads full of other humans and animals and following the rules of the road / restrictions of the environment.

    1. “is a slightly easier problem”
      NASA is aware of the costs of an interplanetary lawsuit resulting from any of their equipment injuring a Martian.

  5. The big difference is that the Mars rovers don’t have to worry about other moving objects that they need to avoid and can drive anywhere they like that the system decides is OK to drive on.

  6. The “here be monsters” part of that graph (the doubly blacked out QG triangle specifically) is actually where Pym Particles take you. Because two impossibilities cancel each other out and make things possible again, you very briefly become an instanton as you transition between normal space and the Quantum Realm.

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