Powered Exoskeletons In Rough Terrain: An Interesting Aspect Of The Chang’e 5 Recovery Mission

January 6, 2021 by Maya Posch 20 Comments

At this point in time, one would be hard pressed to find anyone who is not at least aware of some of the uses of exoskeletons as they pertain to use by humans. From supporting people during rehabilitation, to ensuring that people working in industrial and warehouse settings do not overexert themselves, while also preventing injuries and increasing their ability to carry heavy loads without tiring.

During the recovery mission of the Chang’e 5 sample container in the rough terrain of Inner Mongolia, the crew which was tasked with setting up the communications center, electrical supply systems and other essential services in the area wore exoskeletons. Developed by a relatively new Chinese company called ULS Robotics (see embedded promotional video after the break), the powered exoskeletons allowed the crew to carry 50 kg loads at a time for a hundred meters across the rough, snowy terrain.

The obvious benefit of an exoskeleton here is that while humans are pretty good at navigating rough terrain, this ability quickly degrades the moment a heavy load is involved, as anyone who has done serious mountain trekking can probably attest to. By having the exoskeleton bear most of the load, the wearer can focus on staying upright and reaching the destination quickly and safely.

With the growing interest for exoskeletons from various industries, the military, as well as the elderly, it probably won’t be too long before we’ll be seeing more of them in daily life the coming years.

(Thanks, Qes)

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You Got Something On Your Processor Bus: The Joys Of Hacking ISA And PCI

January 6, 2021 by Maya Posch 32 Comments

Although the ability to expand a home computer with more RAM, storage and other features has been around for as long as home computers exist, it wasn’t until the IBM PC that the concept of a fully open and modular computer system became mainstream. Instead of being limited to a system configuration provided by the manufacturer and a few add-ons that really didn’t integrate well, the concept of expansion cards opened up whole industries as well as a big hobbyist market.

The first IBM PC had five 8-bit expansion slots that were connected directly to the 8088 CPU. With the IBM PC/AT these expansion slots became 16-bit courtesy of the 80286 CPU it was built around. These slots could be used for anything from graphics cards to networking, expanded memory or custom I/O. Though there was no distinct original name for this card edge interface, around the PC/AT era it got referred to as PC bus, as well as AT bus. The name Industry Standard Architecture (ISA) bus is a retronym created by PC clone makers.

With such openness came the ability to relatively easy and cheaply make your own cards for the ISA bus, and the subsequent and equally open PCI bus. To this day this openness allows for a vibrant ecosystem, whether one wishes to build a custom ISA or PCI soundcard, or add USB support to a 1981 IBM PC system.

But what does it take to get started with ISA or PCI expansion cards today? Continue reading “You Got Something On Your Processor Bus: The Joys Of Hacking ISA And PCI” →

Bad Idea For Desoldering Actually Might Be Pretty Smart

January 6, 2021 by Dan Maloney 49 Comments

This video on building a DIY desoldering iron says it all right up front: this is stupid and dangerous, and you shouldn’t do it. But that doesn’t mean it doesn’t work, or that it doesn’t have potential to be turned into something else.

The story begins, as it often does these days, on the pages of Amazon as [AnotherMaker] shopped for a real desoldering setup. Despite a case of sticker shock, he took the plunge on a nice Hakko vacuum desolderer, but as is also often the case, it failed to arrive. Rather than accept defeat, [AnotherMaker] purchased a cheap-o soldering iron and a brass tee fitting for small-bore tubing that would chuck nicely into the spot where the stock tip once lived, giving him a way to both melt solder and move air.

Unfortunately, rather than applying a vacuum, he chose to blast 100 PSI compressed air through the tip, which certainly moves a lot of solder, perhaps at the cost of burns and eye injuries. The potential for accidental short circuits is pretty high too, but c’mon — it’s not like we all haven’t flicked or dropped a board to desolder something. Is this really much different?

As fraught with peril as this method may be, [AnotherMaker] is onto something here. Perhaps adding a 3D-printed venturi generator could turn that blast of air into a vacuum. Or maybe a vacuum pump for a manual pick-and-place would do the trick too.

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Amazon’s Custom T-Shirt May Rub You The Wrong Way

January 6, 2021 by Kristina Panos 49 Comments

How far would you go in pursuit of the perfect black t-shirt? Would you let Amazon build a virtual double of your body? They already know so much about you, so what’s a body scan or two between customer and company?

So here’s the deal — Amazon is trying to launch a brand of bespoke clothing called Made for You, and they’re starting with custom solid color t-shirts. Here’s how it works: you give them $25 along with information about your height, weight, and skin tone. Then you upload two pictures of your torso to their app, and these get turned into a 3D model of your body. Once your avatar is built to match, you design your shirt to fit the model. In theory, you get a really good idea of how it will fit.

You can choose from two different fabrics and eight colors, and can customize the neckline, the shirt length, and the sleeve length. If you want to, you can put your name on the tag. Then your perfect t-shirt gets made in the US from imported fabric — either lightweight or medium weight pima cotton. We’re not sure if robots or people are making them, but our money is on people. After all, Amazon is the company that created Mechanical Turk to form a pool of humans available to do on-demand work via the Internet. This is along those lines but with tailors sewing to your specifications. The big questions are what do you get, how does the technology make these better than off-the-rack, and do you give up your privacy in return?

One-Size Fits One

To say that these are custom t-shirts is a bit of a stretch. Oh you don’t need to worry about the t-shirts being skin-tight and showcasing your spare tire — if it’s a relaxed fit you want, that’s one of the options. But the current options are limited.

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Heat Turns 3D Printer Filament Into Springs

January 6, 2021 by Donald Papp 11 Comments

The next time you find yourself in need of some large-ish plastic springs, maybe consider [PattysLab]’s method for making plastic springs out of spare filament. The basic process is simple: tightly wind some 3D printer filament around a steel rod, secure it and wrap it in kapton tape, then heat it up. After cooling, one is left with a reasonably functional spring, apparently with all the advantages of annealed plastic.

The basic process may be simple, but [PattysLab] has a number of tips for getting best results. The first is to use a 3D-printed fixture to help anchor one end of filament to the steel rod, then use the help of an electric drill to wind the filament tightly. After wrapping the plastic with kapton tape (wrap counter to the direction of the spring winding, so that peeling the tape later doesn’t pull the spring apart), he suspends it in a pre-heated oven at 120 C for PLA and 160 C for PETG. How long does it stay in there? [PattysLab] uses the following method: when the spring is wound, he leaves a couple inches of filament sticking out to act as a visual indicator. When this segment of filament sags down, that’s his cue to begin the retrieval process. After cooling, the result is a compression or extension spring, depending on how it was wound before being heated.

[PattysLab] shared a short video on this Reddit post that shows both springs in action, and the process is all covered in the video, embedded below.

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Custom Controller Makes Turbomolecular Pump Suck

January 6, 2021 by Anool Mahidharia 16 Comments

[Mark Aren] purchased a pair of Turbomolecular pumps (TMP) sans controllers, and then built an FPGA based BLDC controller for the Turbomolecular pumps. A TMP is similar to a jet turbine, consisting of several stages of alternating moving turbine blades and stationary stator blades, and having turbine rotation speeds ranging from 10,000 rpm to 90,000 rpm. TMP’s cannot exhaust directly to atmosphere, and must be combined with a backing (or roughing) pump to create a lower grade vacuum first. They find use in lots of applications such as electron microscopy, analytical sciences, semiconductors and lamp manufacturing. With the lamp industry rapidly embracing LEDs, many of the traditional lamp making lines are getting decommissioned, and if you are lucky, you can snag a TMP at a low cost – but it still will not be cheap by any means.

The two BOC-Edwards EXT255H Compound Molecular Pumps (PDF), that [Mark] bought did not have their accompanying EXC100E Turbomolecular Pump Controllers (PDF), and given pandemic related restrictions, he decided to build a controller of his own, using components and modules from his parts bin. The pump and controller user manuals offered only sketchy details about the sensored BLDC motor used in the pump. The low phase-to-phase resistance implied low drive voltage, and [Mark] decided to try running it at 24 V to start with. He already had experience using the Mitsubishi PS21245-E IGBT inverter bridge, and even though it was rated for much higher voltages, he knew that it would work just fine at 24 V too.

After figuring out a state machine for motor commutation that utilized PWM based adjustable current control, he implemented it on a 128 element FPGA board. Considering how expensive the TMP was, he wisely decided to first try out his driver on a smaller “expendable” BLDC motor. This whole process was non-trivial, since his available IGBT module was untested and undocumented, and required several tweaks before he could run it at the required 12 kHz PWM signals. His test motor was also undocumented, failing to run correctly when first hooked up. Fixing that issue meant having to disassemble the motor to check its internal wiring. Eventually, his efforts paid off, and he was able to safely run the TMP motor to confirm that his design worked.

With FPGA code, IGBT wiring and power supply issues sorted, the next step was to add a supervisory micro-controller, using an Arduino Nano. Its functions included interfacing with a touch screen LCD as a user interface, communicating with the FPGA module, and controlling several relays to switch power to the motor power supply, the roughing pump, TMP cooling fan, and a solenoid for the vacuum vent. Spindle current is calculated by measuring voltage drop across shunt resistors on the low side of the IGBT. Motor speed is measured using one of the motor hall sensors, and a thermistor provides motor temperature sensing. [Mark]’s PCB fabrication technique seems a bit different too. Using an Excellon drill file, he drills holes in a piece of plastic using a laser cutter to create a bare board, and then solders copper tracks by hand.

His initial tests at atmospheric pressure (although not recommended unless you monitor pump temperature), resulted in 7300 rpm while consuming about 7 Amps before he had to shut it down. In further tests, after adding a roughing pump to the test setup, he was able to spin the TMP to 20,000 rpm while it consumed 0.6 A. Obviously, the pump is rated to operate at a higher voltage, possibly 48 V based on the values mentioned in the TMP controller manual. The project is still “work in progress” as [Mark] hopes to eventually drive the pump up to its specified 60,000 rpm operating speed. What is not clear is what he eventually intends to do with this piece of exotic machinery. All he mentions is that “he has recently taken an interest in high-vacuum systems and is interested in exploring the high-vacuum world of electron guns.”

Maybe [Mark] can compare notes with the Open Source Turbomolecular Pump Controller that we featured some time back. And if you’d like to be a little bit more adventurous and build you own TMP, we got you covered with this DIY Everyman’s Turbomolecular Pump.

Xbox Controller Mod Gets Serious About Stick Drift

January 5, 2021 by Tom Nardi 47 Comments

Many a gamer has found that after a few years of racing around the track or sending demons back from whence they came, the analog sticks on their trusty controller can start to drift around. Many times it’s a fairly minor problem, something you might only notice if you were really keeping an eye out for it, but it can definitely be annoying. Those handy with a soldering iron might just swap out the sticks for replacements once it gets to that point, but [Taylor Burley] wondered how difficult it would be to recalibrate the ailing sticks instead.

To be clear, [Taylor] acknowledges this approach is overkill. It would be cheaper and easier to just replace the drifting stick with a new one. Even if you take into account that new sticks might not be as high quality as the originals and could give up the ghost faster, this probably isn’t worth the effort. But that doesn’t mean it’s not an interesting hack.

In the video after the break, [Taylor] starts by explaining how stick drift occurs in the first place. Each axis of the stick is physically connected to the wiper of a potentiometer, so for 10K pots, the stick’s center point should correspond to a resistance of 5K. He then goes on to measure the resistance in a bad joystick, and sure enough, the center resistance is off by several hundred Ohms.

To fix this, he comes up with a simple circuit that places additional potentiometers between the wipers. With two joysticks and two adjustment pots per axis, that makes eight little adjustment wheels that need to be fiddled with to get the center points calibrated properly. In this case [Taylor] uses a controller diagnostic tool for the Xbox to quantify the impact his adjustments are making so he can dial it in perfectly, but the idea is the same no matter who’s logo is on the box.

We’d say this is the most overkill attempt at addressing the issue of stick drift on gaming controllers we’ve ever seen, but that title has to go to [Matteo Pisani], who replaced the analog stick on his Switch Joy-Con with a custom circular touchpad.

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