DingoQuadruped Is A Cheap Canine-Like Robot

June 21, 2023 by 9 Comments

Robot humanoids are cool, but also a bit hard to make work as they only have two legs to stand on. Four-legged robots can be a bit more approachable. The Dingo Quadruped aims to be just such an open-source platform for teaching and experimentation purposes.

The robot is based on the Stanford Pupper, a robot platform we’ve discussed previously. It bears a design not dissimilar from the popular Spot robot from Boston Dynamics. Where Spot costs tens of thousands of dollars, though, Dingo is far cheaper, intended for cheap production by students and researchers for less than $1,500.

The robot weighs around 3 kg, and is approximately the size of a shoebox. Control over the robot is via a wireless game controller. Each leg uses three high-torque servo motors, which are elegantly placed to reduce the inertia of the leg itself. A Raspberry Pi runs the show, with an Arduino Nano also onboard for interfacing analog sensors or additional hardware. The chassis itself has a highly modular design, with a focus on making it easy to add additional hardware.

If you want to get started experimenting with quadruped robots, the Dingo might just be the perfect platform for you. Video after the break.

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3D Printed Machine Shows How Braiding Is Done

June 21, 2023 by 8 Comments

If there’s something more fascinating than watching cleverly engineered industrial machines do their work, we don’t know what it could be. And at the top of that list has to be the machines that do braiding. You’ve probably seen them, with spools of thread or wire dancing under and around each other in an endless ballet that somehow manages to weave a perfect braid. It’s kind of magical.

For those who haven’t seen such a thing, now’s your chance, with this twelve-spool braiding machine. The building methods that [Fraens] used — mainly 3D printing and laser-cut acrylic — make the workings on this machine plain, even to those of us who never learned to manually braid even three strands. It’s far easier to understand by watching the video below than by trying to describe it, but basically, each vertical supply spool runs along a continuous track around a central point by a series of six meshed gears, passing under each other as they progress around the carousel and forming the braid.

There are a ton of details that go into making this work. Chief among them is the thread tensioning mechanism, which is a lever arm and spring-loaded axle that lives at the very center of each spool. The gears that form the inside-outside tracks are quite clever too, as are the worm-gear-driven takeup reel and output tensioner. We also appreciated the gate used to load the spool carriers into the track.

We can recall a couple of braiding machines before, including this one made entirely from Lego Technics.

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Congratulations To Our Op-Amp Challenge Winners!

June 21, 2023 by 15 Comments

The real world is analog, and the op-amp is the indispensable building block of many analog circuits. We wanted to give you analog fanatics out there a chance to shine and to encourage our digital brothers and sisters to dip their toes in the murky waters where ones and zeroes define the ends of a spectrum rather than representing the only choice. Hence, we presented the Op Amp Challenge. And you did not disappoint!

We received 83 entries, and it was extraordinarily hard to pick the winners. But since we had three $150 DigiKey shopping sprees to give away, our six judges buckled down and picked their favorites. Whether or not you’ve got the Golden Rules of the ideal op-amp tattooed on your arm, you’ll enjoy looking through all of the projects here. But without further ado…

The Winners

[Craig]’s Op Art is an X-Y voltage generator to plug into an oscilloscope and make classic Lissajous and other spirograph-like images, and it’s all done in analog. Maybe it was his incredible documentation, the nice use of a classic three-op-amp tunable oscillator, or the pun hidden in the title. Whatever the case, it wowed our judges and picked up a deserved place in the top three.

Hearkening back to the pre-digital dinosaur days, [Rainer Glaschick]’s Flexible Analog Computer is a modular analog computer prototyping system on a breadboard backplane. Since you have to re-wire up an analog computer for your particular, it’s great that [Rainer] gave us a bunch of examples on his website as well, including a lunar lander and classic Lorenz attractor demos.

And there was no way that [Chris]’s interactive analog LED wave array wouldn’t place in the top three. It’s a huge 2D analog simulation that runs entirely on op-amps, sensing when your hand moves across any part of its surface and radiating waves out from there. You have to admire the massive scale here, and you simply must check out the video of it in action. Glorious!

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No Frills Autonomous Lawnmower Gets The Job Done

June 21, 2023 by 19 Comments

[Nathan] needed an autonomous mower to help on the farm, so he built his own without breaking the bank. It might not be the prettiest machine, but it’s been keeping his roads, fences and yard clear for over a year. In the video after the break, he gives a detailed breakdown of its build and function.

It’s built around a around a simple angle-iron frame with a normal internal combustion push mower at it’s core. 18″ bicycle-type wheels are mounted at each corner, each side driven by an e-bike motors via long bicycle chains. Nathan had to add some guards around his wheel sprockets to prevent the chains slipping of due to debris.

Al the electronics and the battery is simply mounted on top of the frame, away from the motors to avoid magnetic interference with the compass. The brain of the system is a Pixhawk autopilot with a GPS module running ArduPilot, a staple for most of the autonomous rovers, boats and aircraft we’ve seen. The control station is just a Windows laptop running Mission Planner, with a 900 MHz radio link for comms with the mower. [Nathan] also gives a overview of how he uses a spreadsheet to set up waypoints.

This lawnmower’s straightforward design and use of easy-to-find components make it an excellent source of inspiration for anyone looking to build their own functional machine.

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In Praise Of RPN (with Python Or C)

June 21, 2023 by 39 Comments

HP calculators, slide rules, and Forth all have something in common: reverse polish notation or RPN. Admittedly, slide rules don’t really have RPN, but you work problems on them the same way you do with an RPN calculator. For whatever reason, RPN didn’t really succeed in the general marketplace, and you might wonder why it was ever a thing. The biggest reason is that RPN is very easy to implement compared to working through proper algebraic, or infix, notation. In addition, in the early years of computers and calculators, you didn’t have much to work with, and people were used to using slide rules, so having something that didn’t take a lot of code that matched how users worked anyway was a win-win.

What is RPN?

If you haven’t encountered RPN before, it is an easy way to express math without ambiguity. For example, what’s 5 + 3 * 6?  It’s 23 and not 48. By order of operations you know that you have to multiply before you add, even if you wrote down the multiplication second. You have to read through the whole equation before you can get started with math, and if you want to force the other result, you’ll need parentheses.

With RPN, there is no ambiguity depending on secret rules or parentheses, nor is there any reason to remember things unnecessarily. For instance, to calculate our example you have to read all the way through once to figure out that you have to multiply first, then you need to remember that is pending and add the 5. With RPN, you go left to right, and every time you see an operator, you act on it and move on. With RPN, you would write 3 6 * 5 +.

While HP calculators were the most common place to encounter RPN, it wasn’t the only place. Friden calculators had it, too. Some early computers and calculators supported it but didn’t name it. Some Soviet-era calculators used it, too, including the famous Elektronika B3-34, which was featured in a science fiction story in a Soviet magazine aimed at young people in 1985. The story set problems that had to be worked on the calculator.

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Fuel Cell Turns PET And Carbon Dioxide Into Useful Chemicals

June 21, 2023 by 17 Comments

The University of Cambridge has a novel fuel cell design that can grab CO2 from the atmosphere or industrial processes and, combined with waste PET plastic, provides syngas and glycolic acid, a product used in some cosmetics. You can read about the device in a recent paper.

The strange juxtaposition of CO2 and PET is no accident. The processes work together with solar energy. There is no external voltage required, but the cell operates as a photocell to produce electricity from the solar energy. Removing both CO2 and waste plastic from the environment is a good thing.

Syngas is hydrogen and carbon monoxide and finds use in producing methanol and ammonia. It also will work as a fuel that can replace gasoline when gasoline isn’t available. It has a few other uses, like reducing iron ore to sponge iron and even converting methanol to gasoline.

The technology has a ways to go to operate at scale, and we doubt this will ever be a consumer item since you are unlikely to need syngas or glycolic acid in your home or vehicle. But it still is a promising technique to reduce both greenhouse gas and plastic waste in one swoop.

We’ve looked at other ways to grab carbon dioxide and make it useful. If you want to make your own syngas, there are other ways to do it.

How To Land A Model Rocket Vertically

June 21, 2023 by 20 Comments

Perhaps most readers will remember when they saw the first SpaceX demonstration of a rocket stage landing vertically on the pad under control. It’s something of a shock to be reminded that their first suborbital demonstration “hops” were around a decade ago, and how quickly what was once so special has become commonplace. We’re now in the era of the more complex model rockets having the same capability, with [BPS.space] managing it last year, and now [TTS Aerospace] sharing a video showing how they achieved the same feat.

The basics of the system revolve around a directed rocket nozzle, but to make it work is a lot more complex than simply hooking up a flight controller and calling it good. The steps in arriving at a landable rocket are examined, with plenty of failures shown along the way. Even the legs are more complex than they might appear, having to combine lightness, ease of unfurling under the power of elastic, and enough strength and give to survive a rough landing.

Those of us from countries where model rocketry is a highly licensed activity can only look on in envy at these projects, and we look forward to seeing where this avenue leads next. We covered the [BPS.space] rocket last year, should you be interested.

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