Author: Bryan Cockfield

1761 Articles

Training A Self-Driving Kart

December 21, 2024 by 1 Comment

There are certain tasks that humans perform every day that are notoriously difficult for computers to figure out. Identifying objects in pictures, for example, was something that seems fairly straightforward but was only done by computers with any semblance of accuracy in the last few years. Even then, it can’t be done without huge amounts of computing resources. Similarly, driving a car is a surprisingly complex task that even companies promising full self-driving vehicles haven’t been able to deliver despite working on the problem for over a decade now. [Austin] demonstrates this difficulty in his latest project, which adds self-driving capabilities to a small go-kart.

[Austin] had been working on this project at the local park but grew tired of packing up all his gear when he wanted to work on his machine-learning algorithms. So he took all the self-driving equipment off of the first kart and incorporated it into a smaller kart with a very small turning radius so he could develop it in his shop.

He laid down some tape on the floor to create the track and then set up the vehicle to learn how to drive by watching and gathering data. The model is trained with a convolutional neural network and this data. The only inputs that the model gets are images from cameras at the front of the kart. At first, it could only change the steering angle, with [Austin] controlling the throttle to prevent crashes. Eventually, he gave it control of the throttle as well, which behaves well except at the fastest speeds.

There were plenty of challenges along the way, especially when compared to the models trained at the park; [Austin] correctly theorized that the cause of the hardship in the park was a lack of contrast at the boundary between the track and any out-of-bounds areas. With a few tweaks to the track, as well as adding some wide-angle lenses to his cameras, he was able to get a model that works fairly well. Getting started on a project like this doesn’t have as high of a barrier to entry as one might imagine, either. Take a look at this comprehensive open-source Python library for self-driving projects. If you want to start smaller, perhaps don’t start with a self-driving kart.

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A Compass That Looks To The Stars

December 17, 2024 by 19 Comments

Although a lot of tools have been digitized and consolidated into our smartphones, from cameras, music players, calendars, alarm clocks, flashlights, and of course phones, perhaps none are as useful as the GPS and navigational capabilities. The major weakness here, though, is that this is a single point of failure. If there’s no cell service, if the battery dies, or you find yourself flying a bomber during World War II then you’re going to need another way to navigate, possibly using something like this Astro Compass.

The compass, as its name implies, also doesn’t rely on using the Earth’s magnetic field since that would have been difficult or impossible inside of an airplane. Instead, it can use various celestial bodies to get a heading. But it’s not quite as simple as pointing it at a star and heading off into the wild blue yonder. First you’ll need to know the current time and date and look those up in a companion chart. The chart lists the global hour angle and the declination for a number of celestial bodies which can be put into the compass. From there the latitude is set and the local hour angle is calculated and set, and then the compass is rotated until the object is sighted. After all of that effort, a compass heading will be shown.

For all its complexity, a tool like this can be indispensable in situations where modern technology fails. While it does rely on precise tabulated astrometric data to be on hand, as long as that’s available it’s almost failsafe, especially compared to a modern smartphone. Of course, you’ll also need a fairly accurate way of timekeeping which can be difficult in some situations.

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Rainwater From The Road To The Garden

December 15, 2024 by 65 Comments

Most small-scale, residential rainwater harvesting systems we’ve seen rely on using an existing roof and downspout to collect water that would otherwise be diverted out into the environment. These are accessible for most homeowners since almost all of the infrastructure needed for it is already in place. [SuburbanBiology] already built one of these systems to take care of his potable water, though, and despite its 30,000 gallon capacity it’s not even close to big enough to also water his garden. But with some clever grading around his yard and a special rainwater system that harvests rain from the street instead of his roof, he’s capable of maintaining a lush food forest despite living through a drought in Texas.

For this build there are actually two systems demonstrated, one which is gravity-fed from the road and relies on one’s entire property sloping away from the street, and a slightly more complex one that’s more independent of elevation. Both start with cutting through a section of sidewalk to pass a 4″ PVC pipe through to the street where the stormwater runoff can be collected. The gravity-fed system simply diverts this into a series of trenches around the property while the second system uses a custom sump pump to deliver the water to the landscaping.

For a system like this a holding tank is not necessary; [SuburbanBiology] is relying on the soil on his property itself to hold onto the rainwater. Healthy, living soil can hold a tremendous amount of water for a very long time, slowly releasing it to plants when they need it. And, at least where he lives, a system like this is actually helpful for the surrounding environment as a whole since otherwise all of the stormwater runoff has to be diverted out of the city or cause a flood, and it doesn’t end up back in an aquifer. If you’re more curious about a potable water system instead, take a look at [SuburbanBiology]’s previous system.

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An IPhone Case Study

December 15, 2024 by 14 Comments

Way back in 2008, Apple unveiled the first unibody Macbook with a chassis milled out of a single block of aluminum. Before that, essentially all laptops, including those from Apple, were flimsy plastic screwed together haphazardly on various frames. The unibody construction, on the other hand, finally showed that it was possible to make laptops that were both lightweight and sturdy. Apple eventually began producing iPhones with this same design style, and with the right tools and a very accurate set of calipers it’s possible to not only piece together the required hardware to build an iPhone from the ground up but also build a custom chassis for it entirely out of metal as well.

The first part of the project that [Scotty] from [Strange Parts] needed to tackle was actually getting measurements of the internals. Calipers were not getting the entire job done so he used a flatbed scanner to take an image of the case, then milled off a layer and repeated the scan. From there he could start testing out his design. After an uncountable number of prototypes, going back to the CAD model and then back to the mill, he eventually settles into a design but not before breaking an iPhone’s worth of bits along the way. Particularly difficult are the recessed areas inside the phone, but eventually he’s able to get those hollowed out, all the screw holes tapped, and then all the parts needed to get a working iPhone set up inside this case.

[Scotty] has garnered some fame not just for his incredible skills at the precision mill, but by demonstrating in incredible detail how smartphones can be user-serviceable or even built from scratch. They certainly require more finesse than assembling an ATX desktop and can require some more specialized tools, but in the end they’re computers like any other. For the most part.

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A Portable Chainsaw Sawmill

December 14, 2024 by 25 Comments

Unless you’re running a commercial logging operation, with specialized saws, log grapples, mills, transportation for the timber, and the skilled workers needed to run everything, it’s generally easier to bring a sawmill to the wood instead of taking the wood to the sawmill. Especially for a single person, something like a chainsaw mill is generally a much easier and cost effective way to harvest a small batch of timber into lumber. These chainsaw mills can still be fairly cumbersome though, but [izzy swan] has a new design that fits an entire mill onto a hand cart for easy transportation in and out of a forest.

The entire mill is built out of a sheet and a half of plywood, most of which is cut into strips and then assembled into box girders for the track. The remainder of plywood is machined on a CNC to create the carriage for the chainsaw to attach as well as a few other parts to fix the log in place. The carriage has a 4:1 reduction gear on it to winch the chainsaw along the length of the log which cuts the log into long boards. After the milling is complete, the entire mill can be disassembled and packed down onto its hand cart where it can be moved on to the next project fairly quickly.

For a portable mill, it boasts respectable performance as well. It can cut logs up to 11 feet in length and about 30 inches across depending on the type of chainsaw bar used, although [izzy swan] has a few improvements planned for the next prototypes that look to make more consistent, uniform cuts. Chainsaws are incredibly versatile tools to have on hand as well, we’ve seen them configured into chop saws, mortisers, and even fixed to the end of a CNC machine.

Thanks to [Keith] for the tip!

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Apple Newton Gets Rebuilt Battery Pack

December 13, 2024 by 14 Comments

We all carry touch screen computers around in our pockets these days, but before the smartphone revolution, there was the personal digital assistant (PDA). While it wasn’t a commercial success, one of the first devices in this category was the Apple Newton. Today they’re sought after by collectors, although most of the ones surviving to this day need a bit of rework to the battery pack. Luckily, as [Robert’s Retro] shows, it’s possible to rebuild the pack with modern cells.

By modern standards, the most surprising thing about these battery packs is both that they’re removable and that they’re a standard size, matching that of AA batteries. The Newton battery pack uses four cells, so replacing them with modern rechargeable AA batteries should be pretty straightforward, provided they can be accessed. This isn’t as easy, though. In true Apple fashion the case is glued shut, and prying it apart can damage it badly enough so it won’t fit back in the tablet after repair is complete. The current solution is to cut a hatch into the top instead and then slowly work on replacing the cells while being careful to preserve the electronics inside.

[Robert’s Retro] also demonstrates how to spot weld these new AA batteries together to prepare them for their new home in the Newton case. With the two rows fastened together with nickel strips they can be quickly attached to the existing electrical leads in the battery pack, and from there it’s just a matter of snapping the batteries into the case and sliding it back into the tablet. If you’re looking for something a bit more modern, though, we’d recommend this Apple tablet-laptop combo, but it’s not particularly easy on the wallet.

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Chaotic System Cooks Meat Evenly

December 11, 2024 by 35 Comments

For better or worse, a lot of human technology is confined to fewer dimensions than the three we can theoretically move about in. Cars and trains only travel two dimensionally with limited exceptions, maps and books generally don’t take advantage of a third dimension, and most computer displays and even the chips that make them work are largely two-dimensional in nature. Most styles of cooking can only apply heat in a single dimension as well, but [Dane Kouttron] wanted to make sure the meat his cookouts took advantage of a truly three-dimensional cooking style by adding a gyroscopic mechanism to the spit.

The first thing that needed to be built were a series of concentric rings for each of the three axes of rotation. Metal tubes were shaped with a pipe bender and then welded into their final forms, with an annealing step to flatten the loops. From there, the rings are attached to each other with a series of offset bearings. The outer tube is mounted above the fire and a single motor spins this tube. Since no piece of meat is perfectly symmetrical (and could be offset on the interior ring a bit even if it were) enough chaos is introduced to the system that the meat is free to rotate in any direction, change direction at any time, and overall get cooked in a more uniform way than a traditional single-dimensional rotating spit.

As a proof of concept [Dane] hosted a cookout and made “gyro” sandwiches (even though the machine may technically be more akin to a gimbal), complete with small Greek flag decorative garnishes. It seems to have been a tremendous success as well. There are a few other novel ways we’ve seen of cooking food over the years, including projects that cook with plasma and much more widely available methods that cook food efficiently using magnets, of a sort.