Hackaday Links: April 21, 2024

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Do humanoid robots dream of electric retirement? Who knows, but maybe we can ask Boston Dynamics’ Atlas HD, which was officially retired this week. The humanoid robot, notable for its warehouse Parkour and sweet dance moves, never went into production, at least not as far as we know. Atlas always seemed like it was intended to be an R&D platform, to see what was possible for a humanoid robot, and in that way it had a heck of a career. But it’s probably a good thing that fleets of Atlas robots aren’t wandering around shop floors or serving drinks, especially given the number of hydraulic blowouts the robot suffered. That also seems to be one of the lessons Boston Dynamics learned, since Atlas’ younger, nimbler replacement is said to be all-electric. From the thumbnail, the new kid already seems pretty scarred and battered, so here’s hoping we get to see some all-electric robot fails soon.

“Enhance… enhance… no, wait — un-enhance.” A Washington state judge has ruled that AI-enhanced video can’t be used as evidence in a murder trial, a ruling that’s certain to raise legal eyebrows. King County Superior Court Judge Leroy McCullogh issued the first-in-the-nation ruling in the case of a man accused of shooting three people outside a Seattle bar in 2021. The defendant’s lawyers tried to submit into evidence cell phone video that had been processed through a machine learning system, in an apparent attempt to make visible details they say are exculpatory. The choice of company to perform the enhancement may have been a mistake, though, since they market themselves mainly to film studios looking to “supercharge” their productions. The prosection objected to the evidence on the grounds that the AI only predicted missing information in the video, rather than enhancing and clarifying existing details in the images. Given the tendency for chat bots to hallucinate, we’d tend to agree with the prosecution, but then again, our future doesn’t ride on a shakey, blurry cell phone video. It was probably even in vertical format.

It’s official — Florida man Alejandro Otero won the cosmic lottery last month as NASA confirms the object that crashed through his roof in March was indeed from the ISS. Granted, there wasn’t much left of the 2,360 kg battery pack by the time it hit the Otero residence in the Gulf Coast town of Naples — just a 0.7-kg metal cylinder. NASA had expected the entire nickel hydride pack, tossed overboard in March of 2021 in favor of lithium batteries, would burn up upon reentry. That ended up being optimistic, and perhaps foreseeable since the surviving fragment was made from inconel, an alloy specifically used in applications involving high temperatures — perhaps not reentry hot, but still. It seems like Otero just wants to get NASA to pay for the repairs to his house, but honestly, if something like that crashes through our roof, we’re just going to fix it ourselves and shut up so we can keep the thing.

A couple of months back we featured a video that showed a drone that had been specially modified to not only fly near high-tension power lines, but to latch onto them and recharge its batteries (last item). It gave us the willies then for some reason, but now that the full research paper that covers the development of the drone is available — nah, it still creeps us out. It’s an impressive bit of kit, to be sure, about which the paper goes into great detail. We speculated about the power transfer method when the video dropped, and it turns out that there is indeed a split-core current transformer that wraps around the cable when the gripper closes. The paper also has a photo of a clamp meter around a conductor (Figure 11) that shows 288 amperes flowing through the cable while the drone is docked, which creeps us out even more since someone had to get uncomfortably close to that cable to get that shot.

We’re just going to leave this video of a gearless right-angle drive here. You’re welcome.

And finally, if you’ve never heard of Oliver Heaviside — and you really should have — you’ll want to watch this video on the story of the “Telegrapher’s Equation.” Aside from having an awesome name and looking like a Victorian version of Wolverine, Heaviside was absolutely brilliant, to the point of understanding Maxwell’s equations enough to simplify them and use them to explain the skin effect mathematically. He also invented coaxial cable as well as the loading coils that still adorn telephone poles to this day. The video is a deep dive into why the first transatlantic telegraph cables were so terrible, and how Fourier, Lord Kelvin, and the study of thermodynamics informed Heaviside’s explanations of how to improve them. Good stuff.

12 thoughts on “Hackaday Links: April 21, 2024

    1. You don’t need to sign up to watch it. I watched it just fine and I don’t have a Facebook account.

      Though I do agree that it would ideally be hosted elsewhere.

  1. That powerline drone would be an excellent device for powerline inspections. It could take video of the lines, use image processing to identify places where there are issues (worn parts, encroaching wildlife or plant life, etc.) and then send a GPS coordinate and pictures/videos to maintenance crews for action. All of this could be done remotely, without an active operator, and without the need for constantly changing batteries.

  2. Heaviside’s ‘simplification’ of Maxwell’s equations eventually lead to the modern MKS system – by which I mean the bizarro fact that we use “meters, kilograms, and seconds” and not “meters, grams, seconds.” Well, that, and the fact that engineers look at weird physicist units and laugh.

    The common mechanical units in the 19th century were all combinations of centimeter, grams, seconds (CGS). But when electrical units came about, people originally just defined Coulomb’s laws as “q1q2/r^2” – no multiplicative constant (Coulomb’s constant was just 1) – it was folded into the definition of charge.

    The electrical units derived from those standards were absurdly inconvenient, and so engineers started working with Big Multiples of them. Ohms were, scale-wise, the resistance of mile-scale telegraph wire, volts were scale-wise the outputs of elementary electrochemical cells. When you related these to the CGS equivalents (which got called ‘ab’ version of the electrical units – for absolute – like abvolt, abampere, abohm) you got those Big Multiples, namely 10^9 abohm = 1 ohm, 10^8 abvolt = 1 volt.

    However, most importantly, 1 watt = 10^7 erg/s. The reason this one’s important is because they’re both power, and power needs to be both current * potential and mass * length^2 / time^2.

    Heaviside realized that the CGS ‘simple Coulomb’s law’ led to dumb geometric factors in Maxwell’s equations: Gauss’s law was “the divergence of the electric field is 4*pi*charge density”, and that 4*pi is utterly meaningless since divergence is a point quantity.

    Whereas if the 4*pi was in *Coulomb’s* law (as 4*pi*r^2), it makes perfect sense there, because it’s just the surface area of a sphere of radius r. He called it a “rational system of units” if pi only appeared if coming from geometry. Heaviside argued for rationalized CGS units (we call this the Heaviside-Lorentz units now) – but those had the drawback of still being inconveniently huge and totally mismatched to engineer’s units. No one’s going to change their units to make Heaviside’s feelings happy.

    In 1904, though, Giorgi combined Heaviside’s rationalization approach along with the basic adage of “don’t piss off the engineers” and realized that if you define “M” and “L” to be the power-of-10 required to go from “cgs” to your new system (so for instance ‘meter’ = 10^2 centimeters, so ‘M’ = 2) – so long as “M+2L=7”, your new unit of power would equal the engineer’s version of power. So you can’t have ‘meter, gram, second’ (and you can’t have ‘meter, tonne, second’ either) but you *can* have ‘meter, kilogram, second’.

    And now the only people who needed to change were the weird physicists who wanted the change for their feelings in the first place, so everyone was happy.

    1. f’crying out loud, meter=10^2 centimeters so ‘L’ = 2, not M.

      M would be 3, since kilogram = 10^3 grams.

      The TL;DR version of this is we have our current MKS system of units because it fixed the mistake Heaviside realized scientists made in defining the equations and it made scientist units equal to electrical engineering units, which were taking over the world anyway.

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