Author: Bryan Cockfield

1761 Articles

A General-Purpose PID Controller

January 27, 2024 by 19 Comments

For those new to fields like robotics or aerospace, it can seem at first glance that a problem like moving a robot arm or flying an RC airplane might be simple problems to solve. It turns out, however, that control of systems like these can get complicated quickly; so much so that these types of problems have spawned their own dedicated branch of engineering. As controls engineers delve into this field, one of their initial encounters with a control system is often with the PID controller, and this open source project delivers two of these general-purpose controllers in one box.

The dual-channel PID controller was originally meant as a humidity and temperature controller and was based on existing software for an ATmega328. But after years of tinkering, adding new features, and moving the controller to an ESP32 platform, [knifter] has essentially a brand new piece of software for this controller. Configuring the controller itself is done before the software is compiled, and it includes a GUI since one of the design goals of the project was ease-of-use. He’s used it to control humidity, temperature and CO2 levels in his own work at the University of Amsterdam, but imagines that it could see further use outside of his use cases in things like reflow ovens which need simple on/off control or for motors which can be controlled through an H-bridge.

The PID controller itself seems fairly robust, and includes a number of features that seasoned controls engineers would look for in their PID controllers. There are additionally some other open-source PID controllers to take a look at like this one built for an Arduino, and if you’re still looking for interesting use cases for these types of controllers one of our favorites is this PID controller built into a charcoal grill.

Upgrading At Least One Component Of A TI Calculator

January 24, 2024 by 12 Comments

Even though Texas Instruments were the first company to produce an integrated circuit and a microprocessor, their success as a company in the 60s and 70s was not guaranteed. At the time there wasn’t much demand for previously non-existent products like these, so to drive some business they built the first hand-held calculator, a venture that they are still famous for today. Since then, though, they’ve become a bit of a punchline for producing calculators with decades-old technology but with modern price tags, so while this business model was quite successful if you want a calculator with a few modern features you’ll have to take a DIY approach like this calculator retrofitted with a LiPo battery.

The modern battery pack, with a lithium polymer battery at its core, includes all of the circuitry needed to integrate it seamlessly into the TI-59 calculator, which is all available on the project’s GitHub page. This calculator originally used a 9V battery, so the new battery pack includes a boost converter to match the 3.7V from the new battery to the needs of the old calculator. It doesn’t stop there, though. The pack is rechargeable from an included USB-C port, has a built-in charge controller, and is housed in its own custom-built case that fits neatly into the calculator where the old battery would sit.

While this wouldn’t be a drop-in replacement for more modern calculators like the TI-83/84 and TI-89, a new case and a different boost converter would solve the problem of the AAA batteries dying during exams. It might make the calculators non-compliant with various standardized testing requirements, though (which TI was also instrumental in developing) so you may want to verify with your testing standard of choice before modifying a calculator you need for an exam. But if all the rules are off, why not add Wi-Fi to it too?

Kites Fill Electricity Generation Gaps

January 22, 2024 by 48 Comments

Looking at a wind turbine from first principles, it’s essentially a set of wings that generate lift in much the same way an airplane wing does. Putting the wings on a rotor and calling them “blades” is not a huge step away from that. But there’s no reason the wing has to rotate, or for that matter be attached to a fixed platform, in order to generate electricity. Anything that generates lift can be used, and this company is demonstrating that with their kite-powered wind generators.

Like other wind energy producers that have used kites to generate electricity, this one is similar in that the kite is flown in a figure-8 pattern downwind where it can harness energy the most efficiently, pulling out a tether which is tied to a generator. When fully extended, it is flown to a position where the wind doesn’t strike the kite as strongly and the tether is reeled in. Unlike other kite generators we’ve seen, though, this one is offered as a turnkey system complete with battery backup and housed in a self-contained shipping unit, allowing it to be deployed quickly to be used in situations where something like a diesel generator would be impossible to get or where the fuel can’t be obtained.

The company, called Kitepower, does note that these aren’t replacements for traditional wind turbines and would be used more for supporting microgrids. There are still some advantages to using kites over fixed turbine blades though: kites can reach higher altitude where the wind is stronger, and they require less materials for a given amount of energy production, often making them even more environmentally friendly and possibly more economical as well. Surprisingly enough, kites can also be used to generate energy even in places where there’s no wind at all.

Modeling Network Latency

January 17, 2024 by 6 Comments

The selfhosting community is an interesting and useful part of the Internet dedicated to removing one’s own services and data from the cloud and hosting it on their own servers, often on hardware that can be physically touched. With that kind of network usage, it’s not uncommon for people to build their own routers, firewalls, and other network support systems from the ground up. And, if you go deep enough, maybe even a home lab dedicated to testing and improving the network’s various layers. This piece of software helps simulate network latency to more accurately assess quality of service, performance, and the optimization of one one’s own networks.

The tool, called Speedbump, allows a network administer to quickly build a test network where characteristics of the network such as base latency and wave shape and size can be set up. From there, a TCP proxy sends the network traffic through the virtual network, adding in a set amount of delay to anything traveling on the network. It can be installed (or built from source) on an existing installation or used from within a Docker terminal, so there are plenty of options depending on preference. It’s also available as a library for any programs written in Go.

While this certainly has applications for home labs where self-hosting services is done at a high level, this could have professional applications as well. For troubleshooting simpler network issues we’d always recommend this tool which allows a more comprehensive network test than the standard “ping” command, and if you haven’t heard of selfhosting before it’s probably time to read this primer on it and build a hobby web server from scratch.

Feeding The Fire By Robot

January 15, 2024 by 24 Comments

It might seem a little bit counterintuitive, but one of the more carbon-neutral ways of heating one’s home is by burning wood. Since the carbon for the trees came out of the air a geologically insignificant amount of time ago, it’s in effect solar energy with extra steps. And with modern stoves and well-seasoned wood, air pollution is minimized as well. The only downside is needing to feed the fire frequently, which [Anders] solved by building a robot.

[Anders]’ system is centered around a boiler, a system which typically sits in a utility area like a basement and directs its heat to the home via another system, usually hot water. An Arduino Mega controls the system of old boat winches and various motors, with a grabber arm mounted at the end. The arm pinches each log from end to end, allowing it to grab the uneven logs one at a time. The robot also opens the boiler door and closes it again when the log is added, and then the system waits for the correct set of temperature conditions before grabbing another log and adding it. And everything can be monitored remotely with the help of an ESP32.

The robot is reportedly low-maintenance as well, thanks to its low speed and relatively low need for precision. The low speed also makes it fairly safe to work around, which was an important consideration because wood still needs to be added to a series of channels every so often to feed the robot, but this is much less often than one would have to feed logs into a boiler if doing this chore manually. It also improves on other automated wood-burning systems like pellet stoves, since you can skip the pellet-producing middleman step. It also eliminates the need to heat your home by burning fossil fuels, much like this semi-automated wood stove.

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Vroomba Gets Upgrades And A Spoiler

January 15, 2024 by 11 Comments

[Electrosync] is the creator and driver of the world’s fastest robotic vaccum cleaner, the Vroomba. It’s a heavily modified roomba capable of speeds of around 60 kph, well beyond the pedaling speed of most bicyclists. Despite being rejected by Guinness for a world record, we’re fairly confident that no other vacuum cleaners have gotten up to these speeds since the Vroomba first hit the streets. That’s not going to stop [electrosync] from trying to top his own record, though, and he’s brought the Vroomba some much needed upgrades.

The first, and perhaps most important, upgrades are to some of the structural components and wheels. The robot is much heavier than comparable RC vehicles and is under much greater strain than typical parts are meant to endure, so he’s 3D printed some parts of the chassis and some new wheels using a nylon-carbon fiber filament for improved strength. The wheels get a custom polyurethane coating similar to last time.

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Simulating A Time-Keeping Radio Signal

January 14, 2024 by 14 Comments

As far as timekeeping goes, there’s nothing more accurate and precise than an atomic clock. Unfortunately, we can’t all have blocks of cesium in our basements, so various agencies around the world have maintained radio stations which, combined with an on-site atomic clock, send out timekeeping signals over the air. In the United States, this is the WWVB station located in Colorado which is generally receivable anywhere in the US but can be hard to hear on the East Coast. That’s why [JonMackey], who lives in northern New Hampshire, built this WWVB simulator.

Normally, clocks built to synchronize with the WWVB station include a small radio antenna to receive the 60 kHz signal and the 1-bit-per-second data transmission which is then decoded and used to update the time shown on the clock. Most of these clocks have internal (but much less precise) timekeeping circuitry to keep themselves going if they lose this signal, but [JonMackey] can go several days without his clocks hearing it. To make up for that he built a small transmitter that generates the proper timekeeping code for his clocks. The system is based on an STM32 which receives its time from GPS and broadcasts it on the correct frequency so that these clocks can get updates.

The small radio transmitter is built using one of the pins on the STM32 using PWM to get its frequency exactly at 60 kHz, which then can have the data modulated onto it. The radiating area is much less than a meter, so this isn’t likely to upset any neighbors, NIST, or the FCC, and the clocks need to be right beside it to update. Part of the reason why range is so limited is that very low frequency (VLF) radios typically require enormous antennas to be useful, so if you want to listen to more than timekeeping standards you’ll need a little bit of gear.