Transportation Hacks

1533 Articles

Self-Driving Library For Python

May 16, 2023 by 3 Comments

Fully autonomous vehicles seem to perennially be just a few years away, sort of like the automotive equivalent of fusion power. But just because robotic vehicles haven’t made much progress on our roadways doesn’t mean we can’t play with the technology at the hobbyist level. You can embark on your own experimentation right now with this open source self-driving Python library.

Granted, this is a library built for much smaller vehicles, but it’s still quite full-featured. Known as Donkey Car, it’s mostly intended for what would otherwise be remote-controlled cars or robotics platforms. The library is built to be as minimalist as possible with modularity as a design principle, and includes the ability to self-drive with computer vision using machine-learning algorithms. It is capable of logging sensor data and interfacing with various controllers as well, either physical devices or through something like a browser.

To build a complete platform costs around $250 in parts, but most things needed for a Donkey Car compatible build are easily sourced and it won’t be too long before your own RC vehicle has more “full self-driving” capabilities than a Tesla, and potentially less risk of having a major security vulnerability as well.

A Bicycle Powered By A Different Kind Of Eddy

May 16, 2023 by 31 Comments

When you think of a bicycle and an Eddy, you’d be forgiven for thinking first of Eddy Merckx, one of the most successful competitive cyclists to ever live. But this bicycle, modified by [Tom Stanton] as shown in the video below the break, has been modified by ditching its direct drive gearing in favor of using the friction-like eddy currents between magnets and copper to transfer power to the wheel.

Before even beginning to construct a mechanism for powering the bicycle, [Tom] had to figure out the basics: what kind of materials could be used for a metal disk? The answer, after much testing, turned out to be copper. What kind of magnets work best, and in what formation? Expensive high grade, aligned North to South pole for added eddy-dragging goodness. Would the mechanism work with any efficiency?

The end result is interesting to watch, and it’s not exactly as you’d have expected. Yes, eddy currents drive the copper hub, but at a 100 RPM difference. Where does all of that energy go? Hint: not to the wheel, and certainly not into propelling the bicycle. All in all it’s a fantastic experiment with unpredictable results.

If bicycle based bumbling about bakes your biscuits, you might appreciate this tennis-ball-enhanced ride too.

Continue reading “A Bicycle Powered By A Different Kind Of Eddy” →

Ask Hackaday: Why Do Self Driving Cars Keep Causing Traffic Jams?

May 8, 2023 by 133 Comments

Despite what some people might tell you, self-driving cars aren’t really on the market yet. Instead, there’s a small handful of startups and big tech companies that are rapidly developing prototypes of this technology. These vehicles are furiously testing in various cities around the world.

In fact, depending on where you live, you might have noticed them out and about. Not least because many of them keep causing traffic jams, much to the frustration of their fellow road users. Let’s dive in and look at what’s going wrong.

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E-Bike Battery Tapped For Off-Grid Laptop Power

May 2, 2023 by 12 Comments

If you’ve travelling via bike, you’ll know there’s a certain advantage to packing light. But what if you need to take your beefy desktop-replacement laptop with you on one of these trips? These power hungry machines can’t go far without their chargers (or a place to plug them in), which generally makes them poor traveling companions.

Luckily, [transistor-man] came up with a solution to this particular problem by reusing his e-bike’s battery pack as a mobile power source for his Lenovo laptop. The energy demands of this particular computer are too high for USB-C Power Delivery, and as such, he had to hack up a way to feed it 20 volts DC via its proprietary square power connector. His bike’s battery puts out between 30 and 42 VDC depending on charge, so at least on paper, it should work out fine. Continue reading “E-Bike Battery Tapped For Off-Grid Laptop Power” →

Machine Vision Automates Trainspotting With Unique Full-Length Portraits

May 2, 2023 by 10 Comments

As hobbies go, trainspotting is just as valid a choice as any — we don’t judge. But it does present certain logistical challenges, such as having to be in visual range of a train to be able to spot it. There’s also the fact that trains are very large objects, and they tend to move very fast. What’s a railfan to do?

If you’re also technically minded, you might try building an automatic trainspotting bot like [jo-m] has. It looks like the hardware end of “Trainbot” is pretty simple since it has been tested on both x86 and Raspberry Pi, and supports both video4linux and Pi cam. The magic is in the software, which is able to detect a train entering the frame, record images, and then stitch them together into one long image. The whole thing is coded in Go and has some interesting bits, like a custom image patch mapping package.

Trainbot gives an unusual view of a train, one that most of us accustomed to watching a train pass at a crossing have never seen. By stitching small chunks of the train as it passes, Trainbot is able to show the entire train in a single image, which would be impossible to do except for being very, very far away from the track. [jo-m] also built a web interface for Trainbot where you can check out the comings and goings yourself. Each passing train’s image is accompanied by data like its velocity and acceleration, length of the train, and time of passage. There’s also a GIF of the original source video, which is pretty cool.

Here in the States, we don’t have a lot of passenger trains to spot, but we do have some really long freight trains. It’d be interesting to see how this works with a train that’s over a mile long; that would be quite an image. Looks like someone at least has the hardware in place to give it a try.

Fail Of The Week: Car Starter Motors Aren’t The Best Fit For EBikes

April 14, 2023 by 40 Comments

A lot of what real engineering is all about is designing to the limits of your materials, with a healthy margin for error. On the other hand, seat-of-the-pants engineering often takes the opposite tack — working with the materials you have and finding their limits after the fact. While the former is more rigorous and better suited to anything where life and limb are on the line, there’s something to be said for the flexibility that informal engineering offers.

[Austin Blake]’s latest eBike is a case study in informal engineering. [Austin] started out wondering if a starter motor from a car engine would make a decent electric bike motor. Our first instinct before watching the video below was to answer that question with a resounding “No!” Yes, starter motors seem like a natural for the job, delivering high torque in a compact package. But starting a car engine is the very definition of a low-duty-cycle application, since it should only take a second or two of cranking to get an engine started. Pressing a motor designed for such a task into continuous duty seems like, well, a non-starter.

And to be fair, [Austin] fully acknowledges this from the start. He even retrofits the motor, wisely replacing the shaft bushings with proper bearings in an attempt to get a better duty cycle. And it works, at least for a while — with the motor, a homebrew battery, and an ESC mounted to a bike frame, the bike was actually pretty peppy. But bearings aren’t the only thing limiting a starter motor to intermittent duty operation. The short drive really heated up the motor, and even with a few ventilation holes knocked in the motor housing, it eventually released the Magic Smoke. The video has all the gory details.

As always, we like to stress that “Fail of the Week” is not necessarily a badge of shame. We appreciate it whenever someone shows us the way not to go, as [Austin] did here. And let’s keep in mind that he’s had success with this approach before, albeit with a much, much bigger starter motor.

Continue reading “Fail Of The Week: Car Starter Motors Aren’t The Best Fit For EBikes” →

It’s Opposite Day For This Novel Wankel Engine

April 14, 2023 by 28 Comments

The Wankel engine seems to pop up in surprising places every so often, only to disappear into the ether before someone ultimately resurrects it for a new application and swears to get it right this time. Ultimately they come across the same problems that other Wankels suffered from, namely poor fuel efficiency and issues with reliability. They do have a surprising power-to-weight ratio and a low parts count, though, which is why people keep returning to this well, although this time it seems like most of the problems might have been solved simply by turning the entire design inside out.

A traditional Wankel engine has a triangular-shaped rotor that rotates around a central shaft inside an oval-shaped housing. This creates three chambers which continually revolve around inside the engine as the rotor spins. The seals that separate the chambers are notoriously difficult to lubricate and maintain. Instead of using a rotor inside of a chamber, this design called the X-Engine essentially uses a chamber inside of a rotor, meaning that the combustion chamber and the seals stay in fixed locations instead of spinning around. This allows for much better lubrication of the engine and also much higher efficiency. By flipping the design on its head it is able to maintain a low moving parts count, high compression ratio, and small power-to-weight ratio all while improving reliability and performance and adding the ability to directly inject fuel rather than rely on carburetion or other less-ideal methods of fuel delivery that other Wankels require.

Astute internal combustion aficionados will note that this engine is still of a two-stroke design, and thus not likely to fully eliminate the emissions problems with Wankels in a way that is satisfactory to regulators of passenger vehicles. Instead, the company is focusing on military, commercial, and aerospace applications where weight is a key driver of design. We’ve seen time and time again how the Wankel fails to live up to its promises though, and we hope that finally someone has cracked the code on one that solves its key issues.