Year: 2018

XLIDAR Is A Merry-Go-Round Of Time-Of-Flight Sensors

June 29, 2018 by 38 Comments

[JRodrigo]’s xLIDAR project is one of those ideas that seemed so attractively workable that it went directly to a PCB prototype without doing much stopping along the way. The concept was to mount a trio of outward-facing VL53L0X distance sensors to a small PCB disk, and then turn that disk with a motor and belt while taking readings. As the sensors turn, their distance readings can be used to paint a picture of the immediate surroundings (at least within about 1 meter, which is the maximum range of the VL53L0X.)

The hardware is made to be accessible and has a strong element of “what you see is what you get.” The distance sensors are on small breakout boards, and the board turns the sensor disk via a DC motor and 3D printed belt drive. Even the method of encoding the disk’s movement and zero position has the same WYSIWYG straightforwardness: a spring contact and an interrupted bare copper trace on the bottom of the sensor disk acts as a physical switch. In fact, exposed copper traces in concentric circular patterns and spring pins taken from an SD card socket are what provide power and communications as the disk turns.

The prototype looks good and sounds like it should work, but how well does it hold up? We’ll find out once [JRodrigo] does some testing. Until then, the board designs are available on the project’s GitHub repository if anyone wants to take a shot at their own approach without starting from scratch.

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How Etak Paved The Way To Personal Navigation

June 29, 2018 by 29 Comments

Our recent “Retrotechtacular” feature on an early 1970s dead-reckoning car navigation system stirred a memory of another pre-GPS solution for the question that had vexed the motoring public on road trips into unfamiliar areas for decades: “Where the heck are we?” In an age when the tattered remains of long-outdated paper roadmaps were often the best navigational aid a driver had, the dream of an in-dash scrolling map seemed like something Q would build for James Bond to destroy.

And yet, in the mid-1980s, just such a device was designed and made available to the public. Dubbed Etak, the system was simultaneously far ahead of its time and doomed to failure by the constellation of global positioning satellites being assembled overhead as it was being rolled out. Given the constraints it was operating under, Etak worked very well, and even managed to introduce some of the features of modern GPS that we take for granted, such as searching for services and businesses. Here’s a little bit about how the system came to be and how it worked.

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When The Going Gets Tough, These Wheels Transform To Tracks

June 29, 2018 by 29 Comments

When we want to build something to go where wheels could not, the typical solution is to use tracks. But the greater mobility comes with trade-offs: one example being tracked vehicles can’t go as fast as a wheeled counterpart. Information released by DARPA’s ground experimental vehicle technology (GXV-T) program showed what might come out of asking “why can’t we switch to tracks just when we need them?”

This ambitious goal to literally reinvent the wheel was tackled by Carnegie Mellon’s National Robotics Engineering Center. They delivered the “Reconfigurable Wheel-Track” (RWT) that can either roll like a wheel or travel on its tracks. A HMMWV serves as an appropriate demonstration chassis, where two or all four of its wheels were replaced by RWTs. In the video (embedded below) it is seen quickly transforming from one mode to another while moving. An obviously desirable feature that looks challenging to implement. This might not be as dramatic of a transformation as a walking robot that can roll up into a wheel but it has the advantage of being more immediately feasible for human-scale vehicles.

The RWT is not the only terrain mobility project in this DARPA announcement but this specific idea is one we would love to see scaled downed to become a 3D-printable robot module. And though our Hackaday Prize Robotics Module Challenge has already concluded, there are more challenges still to come. The other umbrella of GXV-T is “crew augmentation” giving operators better idea of what’s going around them. The projects there might inspire something you can submit to our upcoming Human-Computer Interface Challenge, check them out!

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Linux Fu: Scripting For Binary Files

June 29, 2018 by 31 Comments

If you ever need to write a binary file from a traditional language like C, it isn’t all that hard to do. About the worst thing you might have to deal with is attempts to fake line endings across Windows and Linux, but there’s usually a way to turn that off if it is on by default. However, if you are using some type of scripting language, binary file support might be a bit more difficult. One answer is to use a tool like xxd or t2b (text-to-binary) to handle the details. You can find the code for t2b on GitHub including prebuilt binaries for many platforms. You should be able to install xxd from your system repository.

These tools take very different approaches. You might be familiar with tools like od or hexdump for producing readable representations of binary files. The xxd tool can actually do the same thing — although it is not as flexible. What xxd can even reverse itself so that it can rebuild a binary file from a hex dump it creates (something other tools can’t do). The t2b tool takes a much different approach. You issue commands to it that causes it to write an original hex file.

Both of these approaches have some merit. If you are editing a binary file in a scripting language, xxd makes perfect sense. You can convert the file to text, process it, and then roll it back to binary using one program. On the other hand, if you are creating a binary file from scratch, the t2b program has some advantages, too.

I decided to write a few test scripts using bash to show how it all works. These aren’t production scripts so they won’t be as hardened as they could be, but there is no reason they couldn’t be made as robust as you were willing to make them.

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A LIDAR Scanner Build In Glorious Detail

June 29, 2018 by 15 Comments

LIDAR is a very exciting technology that is only just now starting to become accessible to the DIY market. Think radar, but with lasers. There’s a few different modules starting to pop up for just a few hundred dollars. But what is one to do with a LIDAR module? Well, [David] decided to build a room scanner with his Garmin LIDAR Lite, and it’s a wonderful sight to behold.

The scanner consists of a rotating platform, which is driven by a stepper motor. The platform then contains a second motor which runs a tilt axis, upon which the LIDAR is mounted. By aiming the LIDAR in various directions, and recording the detected range, it’s possible to build a point cloud representation of the surrounding area.

The build uses a couple of STM32 chips to do motor control and interface with the LIDAR, but where this build really shines is the mechanical side of things. [David] goes into serious detail about the machining of the parts that make up the rotating system, and there’s plenty of cool bits and pieces like slip rings to make it all work. There’s even some home casting going on here! Be warned, though: there’s some rather juicy close-ups of lathes in action, so put the kids to bed before watching this one all the way through.

We love to see a well-executed build, and even more so when we get to watch the intricate details of how it came together. If you’re still looking for some more inspiration, we’ve seen other LIDAR room scanners before, too.

Box Joint Jig Does Barcodes

June 29, 2018 by 14 Comments

Woodworking is the fine art of turning dead tree carcasses into precision instruments. That means breaking out the saws and chisels and making many, many precise cuts over and over. If you have a table saw, every problem becomes a piece of wood, or something like that, and we’ve seen some fantastic jigs that make these precision cuts even easier. We’ve never seen something like this, though. It’s a box joint jig for a table saw, it’s automated, and it puts barcodes on boxes.

[Ben] built this box joint jig a few years ago as a computer-controlled device that slowly advances a piece of wood on a sled, allowing him to create precise, programmable box joints. The design is heavily influenced from [Matthias Wandel]’s screw advance box joint jig, but instead of wood gears (heh), [Ben] is using the Internet of Things. Or a Raspberry Pi, stepper motor, and a few LEDs. Same difference.

Although [Ben]’s previous box joints were all the same size, a programmable box joint jig can do some weird-looking joints. That’s where [Ben] got the idea to encode a barcode in walnut. After using a web app to create a barcode that encodes the number 255 — this is important for later — [Ben] programmed his jig to cut a few slots.

The box was finished as you would expect, but there’s a neat addition to the top. It’s a combination lock that opens when the combination is set to 255. It’s brilliant, and something that could be done with some handsaws and chisels, but this jig makes it so easy it’s hard to think the jig wasn’t explicitly designed for this project.

Carousel Of Cereals Mixes And Matches Custom Breakfast Blends

June 28, 2018 by 10 Comments

There are those who reckon the humble bowl of breakfast cereal to be the height of culinary achievement. Look askance if you must, but cereal junkies are a thing, and they have a point. The magic comes not from just filling a bowl and adding a splash of milk, but by knowing which cereals to mix together.

Who needs all that fussy mixing, though, when you can automate and customize your cereal dispensing chores? That’s the approach [Kevin Obermann] and [Adrian Bernhart] took with their Cereal Dispensing Machine, even if they went a little further than necessary. Laser-cut plywood forms a four-station carousel for off-the-shelf dry-good dispensers, each of which got a stepper motor to replace the wrist-twisting. The original motors were a bit too wimpy to handle the more rugged morning selections and were eventually upgraded to gear motors. The platform that supports the dispensers also holds all the electronics, including an ESP32 to run everything and host the web app needed to choose your poison. Plus RGB LEDs, because breakfast should look like a rave. Sadly, the team ran out of GPIO pins and were unable to run the peristaltic pump needed to add the milk. There will always be version 2.0, though.

If cereal isn’t your automated breakfast of choice, we understand. Perhaps a more [Wallace] and [Gromit] style breakfast machine would do, or a robotic peanut butter sandwich any time of day is a treat.

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