Using an FPGA to Navigate China’s Railroads

If you’re headed over to mainland China as a tourist, it’s possible to get to most of the country by rail. China is huge though, about the same size as the United States and more than twice the size of the European Union. Traveling that much area isn’t particularly easy. There are over 300 train terminals in China, and finding the quickest route somewhere is not obvious at all. This is an engineering challenge waiting to be solve, and luckily some of the students at Cornell Engineering have taken a stab at efficiently navigating China’s rail system using an FPGA.

The FPGA runs an algorithm for finding the shortest route between two points, called Dijkstra’s algorithm. With so many nodes this can get cumbersome for a computer to calculate, but the parallel processing of a dedicated FPGA speeds up the process significantly. The FPGA also includes something called a “hard processor system“, or HPS. This is not a soft-core, but dedicated computing hardware in the form of an ARM Cortex-A9. Testing showed that utilizing both the HPS and the FPGA can speed up the computation by up to ten times over a microcontroller alone.

This project goes into extreme detail on the methodology and the background of the math and coding involved, and is definitely worth a read if you’re interested in FPGAs or traveling salesman-esque problems. FPGAs aren’t the only dedicated hardware you can use to solve these kinds of problems though, if you have a big enough backpack while you’re traveling around China you could also use a different kind of computer.

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Handheld GPS Tracks All The Things

With a GPS on every smartphone, one would be forgiven for forgetting that handheld GPS units still exist. Seeking to keep accurate data on a few upcoming trips, [_Traveler] took on a custom-build that resulted in this GPS data logger.

Keeping tabs on [_Traveler] is a Ublox M8N GPS which is on full-time, logging data every 30 seconds, for up  to 2.5 days. All data is saved to an SD card, with an ESP32 to act as a brain and make downloading the info more accessible via WiFi . While tracking the obvious — like position, speed, and time — this data logger also displays temperature, elevation, dawn and dusk, on an ePaper screen which is a great choice for conserving battery.

The prototyping process is neat on this one. The first complete build used point-to-point soldering on a protoboard to link several breakout modules together. After that, a PCB design embraces the same modules, with a footprint for the ESP’s castellated edges and header footprints for USB charing board, SD card board, ePaper, etc. All of this finds a hope in a 3D printed enclosure. After a fair chunk of time coding in the Arduino IDE the logger is ready for [_Traveler]’s next excursion!

As far as power consumption in the field, [_Traveler] says the GPS takes a few moments to get a proper location — with the ESP chewing through battery life all the while — and plans to tinker with it in shorter order.

Not all GPS trackers are created equal: sometimes all you need is a stripped-down tracker for your jog, or to know exactly where every pothole is along your route.

[Via /r/electronics]

Chest of Drawers Stores Audio Memories

Some people collect stamps, some collect barbed wire, and some people even collect little bits of silicon and plastic. But the charmingly named [videoschmideo] collects memories, mostly of his travels around the world with his wife. Trinkets and treasures are easy to keep track of, but he found that storing the audio clips he collects a bit more challenging. Until he built this audio memory chest, that is.

Granted, you might not be a collector of something as intangible as audio files, and even if you are, it seems like Google Drive or Dropbox might be the more sensible place to store them. But the sensible way isn’t always the best way, and we really like this idea. Starting with what looks like an old card catalog file — hands up if you’ve ever greedily eyed a defunct card catalog in a library and wondered if it would fit in your shop for parts storage — [videoschmideo] outfitted 16 drawers with sensors to detect when they’re opened. Two of the drawers were replaced by speaker grilles, and an SD card stores all the audio files. When a drawer is opened, a random clip from that memory is played while you look through the seashells, postcards, and what-have-yous. Extra points for using an old-school typewriter for the drawer labels, and for using old card catalog cards for the playlists.

This is a simple idea, but a powerful one, and we really like the execution here. This one manages to simultaneously put us in the mood for some world travel and a trip to a real library.

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This Electric Longboard Collapses for Air Travel

How do you manage to get an electric off-road longboard past TSA and onto an international flight? Simple — make it a collapsible longboard that fits into a carry-on bag.

The mechanical and electrical feats accomplished by [transistor-man] may not be the most impressive parts of this hack. We’re pretty impressed by the build, starting as it did with the big knobby tires and front truck from an unused mountain board and the hub motor from a hoverboard, turning this into a trike. The incredible shrinking chassis comes courtesy of a couple of stout drawer slides and cam locks to keep it locked in place; collapsed, the board fits in a carry on bag. Expanded, it runs like a dream, as the video below shows.

But we think the really interesting part of this hack is the social engineering [transistor-man] did to ensure that the authorities wouldn’t ground his creation for electrical reasons. It seems current rules limit how big a battery can be and how many of them can be brought on a flight, so there was a lot of battery finagling before his creation could fly.

Electric longboards look like a real kick, whether they be all-aluminum or all-plastic, or even all-LEGO. This one, which went from concept to complete a week and a half before the flight, really raises the bar.

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The ‘All-Seeing Pi’ Aids Low-Vision Adventurer

Adventure travel can be pretty grueling, what with the exotic locations and potential for disaster that the typical tourist destinations don’t offer. One might find oneself dangling over a cliff for that near-death-experience selfie or ziplining through a rainforest canopy. All this is significantly complicated by being blind, of course, so a tool like this Raspberry Pi low-vision system would be a welcome addition to the nearly-blind adventurer’s well-worn rucksack.

[Dan] has had vision problems since childhood, but one look at his YouTube channel shows that he doesn’t let that slow him down. When [Dan] met [Ben] in Scotland, [Ben] noticed that he was using his smartphone as a vision aid, looking at the display up close and zooming in to get as much detail as possible from his remaining vision. [Ben] thought he could help, so he whipped up a heads-up display from a Raspberry Pi and a Pi Camera. Mounted to a 3D-printed frame holding a 5″ HDMI display and worn from a GoPro head mount, the camera provides enough detail to help [Dan] navigate, as seen in the video below.

The rig is a bit unwieldy right now, but as proof of concept (and proof of friendship), it’s a solid start. We think a slimmer profile design might help, in which case [Ben] might want to look into this Google Glass-like display for a multimeter for inspiration on version 2.0.

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Growing Plants on Mars… on Earth

One of the biggest challenges of traveling to Mars is that it’s far away. That might seem obvious, but that comes with its own set of problems when compared to traveling to something relatively close like the Moon. The core issue is weight, and this becomes a big deal when you have to feed several astronauts for months or years. If food could be grown on Mars, however, this would make the trip easier to make. This is exactly the problem that [Clinton] is working on with his Martian terrarium, or “marsarium”.

The first task was to obtain some soil that would be a good analog of Martian soil. Obtaining the real thing was out of the question, as was getting similar dirt from Hawaii. [Clinton] decided to make his own by mixing various compounds from the hardware store in the appropriate amounts. From there he turned to creating the enclosure and filling it with the appropriate atmosphere. Various gas canisters controlled by gas solenoid valves mixed up the analog to Martian atmosphere: 96% dioxide, 2% argon, and 2% nitrogen. The entire experiment was controlled by an Intel Edison with custom circuits for all of the sensors and regulating equipment. Check out the appropriately dramatic video of the process after the break.

While the fern that [Clinton] planted did survive the 30-day experiment in the marsarium, it wasn’t doing too well. There’s an apparent lack of nitrogen in Martian soil which is crucial for plants to survive. Normally this is accomplished when another life form “fixes” nitrogen to the soil, but Mars probably doesn’t have any of that. Future experiments would need something that could do this for the other plants, but [Clinton] notes that he’ll need a larger marsarium for that. And, if you’re not interested in plants or Mars, there are some other interesting ramifications of nitrogen-fixing as well.

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Off-Grid Travel — Setting Up a Solar System

When you’re living out of a vehicle, or even just traveling out of one, power quickly becomes a big concern. You need it for lights, to charge your various devices, to run your coffee maker and other appliances, and possibly even to store your food if you’ve got an electric refrigerator. You could do what many RV owners do: rely on campgrounds with electrical hookups plus a couple of car batteries to get you from one campground to the next. But, those campgrounds are pricey and often amount to glorified parking lots. Wouldn’t it be better if you had the freedom to camp anywhere, without having to worry about finding somewhere to plug in?

That’s exactly what we’re going to be covering in this article: off-grid power on the road. There are two major methods for doing this: with a portable gas generator, or with solar. Gas generators have long been the preferred method, as they provide a large amount of power reliably. However, they’re also fairly expensive, cumbersome, noisy, and obviously require that you bring along fuel. Luckily, major advances in solar technology over the past decade have made it very practical to use solar energy as your sole source of electricity on the road.

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