Three-Wheeled Turret Car Looks Like It Should Be Orbiting Thunderdome

November 12, 2020 by 31 Comments

In a post-apocalyptic world, this is the hacker you want rebuilding society. He’s showing off a three-wheeled go-kart that pivots the cockpit as it steers. A hand crank mounted at the center of the vehicle pivots each of the three wheels in place, but keeps the driver facing forwards with a matching rotation. Hit up the video after the break to see it for yourself.

The real question here is, how did he pull this off? The watermark on the video shows that this was published by [wo583582429], a user on Douyin (the platform known as TikTok in the US). We plied our internet-fu but were unable to track down the user for more of the juicy details we crave. If you have a lead on more info, leave it in the comments below. For now, please join us in speculating on this build.

This is a pretty good closeup of one of the wheel assemblies. First question is how does the turning mechanism work? Since all three wheels and hub are smoothly coordinated it’s likely this is a planetary gearing setup where the inner ring has teeth that turn the rings around the tires themselves. However, we can see a spring suspension system which makes us doubt the lower ring surrounding the tire would stay engaged with a planetary gear. What do you think?

Trying to figure out how control and locomotion happens is even more of a head-scratcher. First guess is that it’s electric from the mere simplicity of the setup and this closeup shows what looks like a circuit breaker and wires connecting to batteries on either side of the suspension system. But where is the electric motor?

It’s a horrible image, but this is the best we can do for a view of the other side of the wheel assembly. There is a box that appears to be made from aluminum mounted to the wheel frame. After a few hundred times through the demo video we don’t think there’s a chain drive going down to the axle. It doesn’t look like there is a hub motor at play here either. We wondered if there was a second smaller wheel under the top of the frame to drive the main tire, but again, the suspension system would make this unfeasible and at points in the video there is clear daylight. Spend some time reviewing the Zapruder demo film below and when you figure all of this out, clue the rest of us in please!

It’s awesome seeing bootstrapped vehicles come to life. One of our favorites remains this all-terrain motorcycle that has no problem taking on stairs.

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Tech Hidden In Plain Sight: Gas Pumps

November 12, 2020 by 67 Comments

Ask someone who isn’t technically inclined how a TV signal works or how a cell phone works, or even how a two-way switch in a hall light works and you are likely to get either a blank stare or a wildly improbable explanation. But there are some things so commonplace that even the most tech-savvy of us don’t bother thinking about. One of these things is the lowly gas pump.

Gas pumps are everywhere and it’s a safe bet to assume everyone reading this has used one at some point, most of use on a regular basis. But what’s really going on there?

Most of it is pretty easy to figure out. As the name implies, there must be a pump. There’s some way to tell how much is pumping and how much it costs and, today, some way to take the payment. But what about the automatic shut off? It isn’t done with some fancy electronics, that mechanism dates back decades. Plus, we’re talking about highly combustible materials, there has to be more to it then just a big tank of gas and a pump. Safety is paramount and, experientially, we don’t hear about gas stations blowing up two or three times a day, so there must be some pretty stout safety features. Let’s pay homage to those silent safety features and explore the tricks of the gasoline trade.

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Meticulous Bionic Hand

November 12, 2020 by 12 Comments

[Will Cogley] is slowly but surely crafting a beautiful bionic hand. (Video, embedded below.) The sheer amount of engineering and thought that went into the design is incredible. Those who take their hands for granted often don’t consider the different ways that their digits can move. There is lateral movement, rotation, flexion, and extension. Generally, [Will] tries to design mechanisms with parts that can be 3D printed or sourced easily. This constrains the hand to things like servos, cable actuation, or direct drive.

However, the thumb has a particularly tricky range of motion. So for the thumb [Will] designed to use a worm geared approach to produce the flexing and extension motion of the thumb. These gears need to be machined in order to stand up to the load. A small side 3d printed gear that connects to the main worm gear is connected to a potentiometer to form the feedback loop. Since it isn’t bearing any load, it can be 3d printed. While there are hundreds of little tiny problems still left to fix, the big problems left are wire management, finalizing the IP (Interphalangeal) joints, and attaching the whole assembly to the forearm.

All the step files, significants amounts of research, and definitions are all on [Will’s] GitHub. If you’re looking into creating any sort of hand prosthetic, the research and attention [Will] has put into this is work incorporating into your project. We’ve seen bionic hands before as well as aluminum finger replacements, but this is a whole hand with fantastic range and fidelity.

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After Eight-Month Break, Deep Space Network Reconnects With Voyager 2

November 12, 2020 by 48 Comments

When the news broke recently that communications had finally been re-established with Voyager 2, I felt a momentary surge of panic. I’ve literally been following the Voyager missions since the twin space probes launched back in 1977, and I’ve been dreading the inevitable day when the last little bit of plutonium in their radioisotope thermal generators decays to the point that they’re no longer able to talk to us, and they go silent in the abyss of interstellar space. According to these headlines, Voyager 2 had stopped communicating for eight months — could this be a quick nap before the final sleep?

Thankfully, no. It turns out that the recent blackout to our most distant outpost of human engineering was completely expected, and completely Earth-side. Upgrades and maintenance were performed on the Deep Space Network antennas that are needed to talk to Voyager. But that left me with a question: What about the rest of the DSN? Could they have not picked up the slack and kept us in touch with Voyager as it sails through interstellar space? The answer to that is an interesting combination of RF engineering and orbital dynamics.

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Quick And Dirty Trebuchet Flings Mashed Potato

November 12, 2020 by 9 Comments

Thanksgiving is just round the corner and [mrak_ripple] was worried about serving food under social distancing conditions. Rather than bother with standard best practice, he chose to take a more exciting route – flinging side dishes with miniature siege weaponry. (Video, embedded below.)

The mashed potato trebuchet is a build in the modern style, relying on 8020 aluminium extrusion to allow for quick and easy assembly. It also takes advantage of what appears to be a heavy duty laser cutter, which creates strong steel brackets to hold everything together. The launcher cup to hold the mash is a 3D printed part, created in resin and held on the end of the arm with duct tape, since appropriate bolts didn’t fall to hand.

In the end, repeatability was a struggle, and we suspect the trebuchet won’t actually do food service on the holiday itself. However, it could certainly make for a fun game after dinner, seeing who can get the most mash onto a willing target. We’d love to see a mash cannon too, so if you’ve built one, drop us a line. Of course, if you’re into weirder, high performance designs, the flywheel trebuchet may be more your speed. Video after the break.

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Really Useful Robot

November 12, 2020 by 8 Comments

[James Bruton] is an impressive roboticist, building all kinds of robots from tracked, exploring robots to Boston Dynamics-esque legged robots. However, many of the robots are proof-of-concept builds that explore machine learning, computer vision, or unique movements and characteristics. This latest build make use of everything he’s learned from building those but strives to be useful on a day-to-day basis as well, and is part of the beginning of a series he is doing on building a Really Useful Robot. (Video, embedded below.)

While the robot isn’t quite finished yet, his first video in this series explores the idea behind the build and the construction of the base of the robot itself. He wants this robot to be able to navigate its environment but also carry out instructions such as retrieving a small object from a table. For that it needs a heavy base which is built from large 3D-printed panels with two brushless motors with encoders for driving the custom wheels, along with a suspension built from casters and a special hinge. Also included in the base is an Nvidia Jetson for running the robot, and also handling some heavy lifting tasks such as image recognition.

As of this writing, [James] has also released his second video in the series which goes into detail about the mapping and navigation functions of the robots, and we’re excited to see the finished product. Of course, if you want to see some of [James]’s other projects be sure to check out his tracked rover or his investigations into legged robots.

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Homebrew Slide Rule Gets Back To Mathematical Basics

November 11, 2020 by 49 Comments

In the grand scheme of things, it really wasn’t all that long ago that a slide rule was part of an engineer’s every day equipment. Long before electronic calculators came along, a couple of sticks of wood inscribed with accurate scales was all it took to do everything from simple multiplication to logarithms and trig functions.

While finding a slide rule these days isn’t impossible, it’s still not exactly easy, and buying one off the shelf isn’t as fun or as instructive as building one yourself. [JavierL90]’s slide rule build started, ironically enough, on the computer, with a Python program designed to graphically plot the various scales needed for the fixed sections of the slide rules (the “stators”) and the moving bit (the “slide”).  His first throught was to laser-engrave the scales, but the route of printing them onto self-adhesive vinyl stock proved to be easier.

With the scale squared away, work turned to the mechanism itself. He chose walnut for the wood, aluminum for the brackets, and a 3D-printed frame holding a thin acrylic window for the sliding cursor. The woodworking is simple but well-done, as is the metalwork. We especially like the method used to create the cursor line — a simple line scored into the acrylic with a razor, which was then filled with red inks. The assembled slide rule is a thing of beauty, looking for all the world like a commercial model, especially when decked out with its custom faux leather carry case.

We have to admit that the use of a slide rule is a life skill that passed us by, but seeing this puts us in the mood for another try. We might have to start really, really simple and work up from there.