Ourobot: What Happens When A Snake Bot Swallows Its Own Tail

July 20, 2016 by 21 Comments

For all their joking about “reinventing the wheel”, the team behind Ourobot made a very cool robot (German, automatic translation here). The team, at the University of Applied Sciences in “Bielefeld, Germany“,  built their wheel out of twelve segments, each with its own servo motor, a 3D-printed case, and a pressure sensor mounted on the outside of the wheel. The latter, plus some clever programming, allows the robot wheel to vary its circular gate and climb up over obstacles automatically.

One link in the chain
One link in the chain

There are a bunch of interesting constraints in designing the control for this bot. The tracks on the ground, naturally, have to adjust their relative angles so that they lie each flat on the surface, even if that surface isn’t itself flat or level. The segments in the air are unconstrained, but the sum of all the servos’ interior angles has to add up to 1800 degrees, and these angles control where its center of gravity is.

Our head is spinning. The paper, “OUROBOT – A Self-Propelled Continuous-Track-Robot for Rugged Terrain” is unfortunately behind the IEEE paywall, but goes into detail if you can find it. Continue reading “Ourobot: What Happens When A Snake Bot Swallows Its Own Tail” →

Case Modding The Old School Way

July 17, 2016 by 11 Comments

Since the release of the Raspberry Pi, the hallowed tradition of taking game consoles, ripping all the plastic off, and stuffing the components into nice, handheld form factors has fallen off the wayside. That doesn’t mean people have stopped doing it, as [Akira]’s masterful handiwork shows us.

This casemod began with a Nintendo GameCube ASCII keyboard controller, a slightly rare GameCube controller that features a full keyboard smack dab in the middle. While this keyboard controller was great for Phantasy Star Online and throwing at the TV after losing Smash, the uniqueness of this controller has outshadowed its usefulness. [Akira] began his build by ripping out the keyboard and installing a 7 inch LCD. It fits well, and makes for a very unique GameCube case mod.

The rest of the build is about what you would expect – the motherboard for a PAL GameCube is stuffed inside, a quartet of 18650 batteries provide the power, and the usual mods – a memory card is soldered to the motherboard and an SD Gecko allows homebrew games and emulators to be played.

The completed project is painted with the same theme as [Samus Arans]’ Varia suit, making this a one of a kind casemod that actually looks really, really good.

Build A 3D Printer Workhorse, Not An Amazing Disappointment Machine

July 6, 2016 by 68 Comments

3D printers have become incredibly cheap, you can get a fully workable unit for $200 – even without throwing your money down a crowdfunded abyss. Looking at the folks who still buy kits or even build their own 3D printer from scratch, investing far more than those $200 and so many hours of work into a machine you can buy for cheap, the question “Why the heck would you do that?” may justifiably arise.

The answer is simple: DIY 3D printers done right are rugged workhorses. They work every single time, they never break, and even if: they are an inexhaustible source of spare parts for themselves. They have exactly the quality and functionality you build them to have. No clutter and nothing’s missing. However, the term DIY 3D printer, in its current commonly accepted use, actually means: the first and the last 3D printer someone ever built, which often ends in the amazing disappointment machine.

This post is dedicated to unlocking the full potential in all of these builds, and to turning almost any combination of threaded rods and plywood into a workshop-grade piece of equipment.

Continue reading “Build A 3D Printer Workhorse, Not An Amazing Disappointment Machine” →

Using The Vive’s Lighthouse With DIY Electronics

July 6, 2016 by 31 Comments

The HTC Vive is the clear winner of the oncoming VR war, and is ready to enter the hallowed halls of beloved consumer electronics behind the Apple Watch, Smart Home devices, the 3Com Audrey, and Microsoft’s MSN TV. This means there’s going to be a lot of Vives on the secondhand market very soon, opening the doors to some interesting repurposing of some very cool hardware.

[Trammell Hudson] has been messing around with the Vive’s Lighthouse – the IR emitting cube that gives the Vive its sense of direction. There’s nothing really special about this simple box, and it can indeed be used to give any microcontroller project an orientation sensor.

The Vive’s Lighthouse is an exceptionally cool piece of tech that uses multiple scanning IR laser diodes and a bank of LEDs that allows the Vive to sense its own orientation. It does this by alternately blinking and scanning lasers from left to right and top to bottom. The relevant measurements that can be determined from two Lighthouses are the horizontal angle from the first lighthouse, the vertical angle from the first lighthouse, and the horizontal angle from the second lighthouse. That’s all you need to orient the Vive in 3D space.

To get a simple microcontroller to do the same trick, [Trammell] is using a fast phototransistor with a 120° field of view. This setup only works out to about a meter away from the Lighthouses, but that’s enough for testing.

[Trammell] is working on a Lighthouse library for the Arduino and ESP8266, and so far, everything works. He’s able to get the angle of a breadboard to a Lighthouse with just a little bit of code. This is a great enabling build that is going to allow a lot of people to build some very cool stuff, and we can’t wait to see what happens next.

Hackaday Prize Entry: Reverse GPS

June 22, 2016 by 19 Comments

Every time you watch a SpaceX livestream to see a roaring success or fireball on a barge (pick your poison), you probably see a few cubesats go up. Everytime you watch a Soyuz launch that is inexplicably on liveleak.com before anywhere else, you’re seeing a few cubesats go up. There are now hundreds of these 10 cm satellites in orbit, and SatNogs, the winner of the Hackaday Prize a two years ago, gives all these cubesats a global network of ground stations.

There is one significant problem with a global network of satellite tracking ground stations: you need to know the orbit of all these cubesats. This, as with all Low Earth Orbit deployments that do not have thrusters and rarely have attitude control, is a problem. These cubesats are tumbling through the rarefied atmosphere, leading to orbits that are unpredictable over several months.

[hornig] is working on a solution to the problem of tracking hundreds of cubesats that is, simply, reverse GPS. Instead of using multiple satellites to determine a position on Earth, this system is using multiple receiving stations on Earth’s surface to determine the orbit of a satellite.

The hardware for [hornig]’s Distributed Ground Station Network is as simple as you would expect. It’s just an RTL-SDR TV tuner USB dongle, a few antennas, a GPS receiver, and a Raspberry Pi connected to the Internet. This device needs to be simple; unlike SatNogs, where single base station in the middle of nowhere can still receive data from cubesats, this system needs multiple receivers all within the view of a satellite.

The modern system of GPS satellites is one of the greatest technological achievements of all time. Not only did the US need to put highly accurate clocks in orbit, the designers of the system needed to take into account relativistic effects. Doing GPS in reverse – determining the orbit of satellites on the ground – is likewise a very impressive project, and something that is certainly a contender for this year’s Hackaday Prize.

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Make Math Real With This Analog Multiplier Primer

June 19, 2016 by 11 Comments

Remember learning all about functions in algebra? Neither do we. Oh sure, most of us remember linear plots and the magic of understanding y=mx+b for the first time. But a lot of us managed to slide by with only a tenuous grasp of more complex functions like exponentials and conic sections. Luckily the functionally challenged among us can bolster their understanding with this demonstration using analog multipliers and op amps.

[devttys0]’s video tutorial is a great primer on analog multipliers and their many uses. Starting with a simple example that multiplies two input voltages together, he goes on to show circuits that output both the square and the cube of an input voltage. Seeing the output waveform of the cube of a ramped input voltage was what nailed the concept for us and transported us back to those seemingly wasted hours in algebra class many years ago. Further refinements by the addition of an op amp yield a circuit that outputs the square root of an input voltage, and eventually lead to a voltage controlled resistor that can attenuate an input signal depending on its voltage. Pretty powerful stuff for just a few chips.

The chip behind [devttys0]’s primer is the Analog Devices AD633, a pretty handy chip to have around. For more on this chip, check out [Bil Herd]’s post on analog computing.

Continue reading “Make Math Real With This Analog Multiplier Primer” →

GNU Radio For Space (and Aircraft)

June 10, 2016 by 10 Comments

GOMX-3 is a CubeSat with several payloads. One of them is a software defined radio configured to read ADS-B signals sent by commercial aircraft. The idea is that a satellite can monitor aircraft over oceans and other places where there no RADAR coverage. ADB-S transmits the aircraft’s ID, its position, altitude, and intent.

The problem is that ADS-B has a short-range (about 80 nautical miles). GOMX-1 proved that the signals can be captured from orbit. GOMX-3 has more capability. The satellite has a helical antenna and an FPGA.

Continue reading “GNU Radio For Space (and Aircraft)” →