Screw Drive Tractor Is About To Conquer Canada

May 5, 2016 by Moritz Walter 29 Comments

The incredible screw drive tractor is back. We’ve covered the previous test ride, which ended with a bearing pillow block ripping in half, but since then, again, a lot of repair work has been done. [REDNIC79] reinforced the load-bearing parts and put on a fresh pair of “tires”. The result is still as unbelievable as the previous versions, but it now propels itself forward at a blazing 3 mph (this time without tearing itself apart).

[REDNIC79] walks us through all the details of the improvements he made since the first version. After the last failure, he figured, that a larger screw pod diameter would give the vehicle a better floatation while smaller thread profile would prevent the screws from digging too deep into the ground, thus reducing the force required to move the vehicle forward.

[REDNIC79] found four identical 100 pounds, 16 inch diameter propane tanks to build the new pods from. The tanks were a bit too short for the tractor, so he cut open two of the tanks and used them to extend the other two before welding a double thread screw onto each. He also tapered the front ends of the tanks to make the ride even smoother. After mounting the new pods to the speedster, a pair of custom steel chain guards were added to prevent rocks from getting into the chain. And then, it was time for another test ride. Enjoy the video:

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35 MPH NERF Darts!

May 5, 2016 by Elliot Williams 15 Comments

Did you know the muzzle velocity of a NERF dart out of a toy gun? Neither did [MJHanagan] until he did all sorts of measurement. And now we all know: between 35 and 40 miles per hour (around 60 km/h).

First, he prototyped a single beam-break detector (shown above) and then expanded his build to two in order to get velocity info. A Propeller microcontroller took care of measuring the timing. Then came the gratuitous statistics. He took six different darts and shot them each 21 times, recording the timings. Dart #3 was the winner, but they all had similar average speeds. You’re not going to win the office NERF war by cherry-picking darts.

Anyway, [MJ] and his son had a good time testing them out, and he thinks this might make a good kids’ intro to science and statistics. We think that’s a great idea. You won’t be surprised that we’ve covered NERF chronographs before, but this implementation is definitely the scienciest!

Thanks [drudrudru] for the tip!

Reverse Engineer Your Robot Lawnmower

May 4, 2016 by Elliot Williams 21 Comments

Your home is your castle, and you are king or queen of all you survey. You’ve built your own home-automation system from scratch. Why would you possibly settle for the stock firmware in your robotic lawnmower? [Daniel Wiegert] wouldn’t either, so in Project Landlord he has started to reverse-engineer it.

You can hardly blame him. The Worx Landroid‘s controller board uses an NXP LPC1768 ARM Cortex-M3, and the debug pins are labelled on the backside. The manufacturer didn’t protect the flash memory. It’s just begging to have its firmware dumped. So far, [Daniel] has managed to both brick and unbrick the device, and has completely mapped the controller’s pinout, so he’s on his way to complete control.

Right now, he’s got a working proof-of-concept firmware on his GitHub that’s able to drive the machine around a little bit and set the brakes. It’s running FreeRTOS, and [Daniel] is looking for other people to get in on the project. He’s done the hard initial work, so get in there and reap the rewards! Just don’t neglect to remove the blade before custom firmware.

Will custom firmware in a robotic lawnmower change the world? Probably not. But it is awesome, and will certainly make a difference in the lives of people whose robot mowers continually get stuck behind the hydrangeas.

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Infrared Detector Selects Over A Wide Range

May 4, 2016 by Al Williams 10 Comments

You can classify infrared light into three broad ranges: short wave, medium wave, and long wave. Traditionally, sensors concentrate on one or two bands, and each band has its own purpose. Short wave IR, for example, produces images similar to visible light images. Long wave is good for thermal imaging.

Researchers have announced a new detector that, by adjusting a bias, can detect all three bands using a simple approach that stacks different absorption layers over a semiconductor substrate. The device only requires two terminals and is very efficient, although the efficiency varies based on the band.

We’ve covered infrared sensing before. We’ve even seen DSLRs hacked into IR sensors. This new research might be a bit much to duplicate in your garage. After all, it requires tellurium doped gallium antimonide substrates and sophisticated processing equipment. However, this research will probably lead to practical devices that will find their way into projects before too long.

What’s The Weather Like For The Next Six Hours?

May 4, 2016 by Gerrit Coetzee 10 Comments

The magic glowing orb that tells the future has been a popular thing to make ever since we realized we had the technology to bring it out of the fortune teller’s tent. We really like [jarek319]’s interpretation of the concept.

Sitting mystically above his umbrella stand, with a single black cord providing the needed pixies for fortune telling, a white cube plays an animation simulating the weather outside for the next six hours. If he sees falling drops, he knows to grab an umbrella before leaving the house. If he sees a thunderstorm, he knows to get the umbrella with the fiberglass core in order to prevent an intimate repeat of Mr. Franklin’s early work.
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Your Quadcopter Has Three Propellers Too Many

May 4, 2016 by Elliot Williams 50 Comments

While studying failure modes for quadcopters, and how to get them safely to the ground with less than a full quad of propellers, a group of researchers at the Institute for Dynamic Systems and Control at ETH Zurich came up with a great idea: a mode of flight that’s like the controlled spinning descent of a maple seed.

The Monospinner runs on the absolute minimum number of moving parts. Namely, one. Even a normal helicopter has a swash plate for adjustable blade pitch, and a tail rotor to keep it from spinning. Give up the idea that you want to keep it from spinning, and you can achieve controlled flight with a lot less. Well, one motor and a whole lot of math and simulation.

The Monospinner is carefully weighted so that it’s as stable as possible while spinning, but so far it’s unable to spin itself up from a standstill. In initial tests, they attached it to a pivot to help. The best part of the video (below) is when the researcher throws it, spinning, into the air and it eventually stabilizes. Very cool.

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JIT Learning Using Expert Systems

May 4, 2016 by Brian Benchoff 51 Comments

Chris Gammell is a guy that should need no introduction around these parts. He’s a co-host on The Amp Hour, and the guy behind Contextual Electronics, a fabulous introduction to electronics and one of the best ways to learn KiCad. If you want to talk about the pedagogy of electronics, this is the guy you want.

Chris’ talk at the Hackaday | Belgrade conference was on just that – the pedagogy of electronics. Generally, there are two ways to learn how to blink an LED. The first, the bottom-up model taught in every university, is to first learn Ohm’s law, resistance, current, voltage, solve hundreds of resistor network problems, and eventually get around to the ‘electrons and holes’ description of a semiconductor. The simplest semiconductor is a diode, and sometime in the sophomore or junior year, the student will successfully blink a LED.

The second, top-down method is much simpler. Just wire up a battery, resistor, switch, and LED to a breadboard. This is the top-down model of electronics design; you don’t need to know everything to get it to work. You don’t need to do it with a 555, and you certainly don’t have to derive Maxwell’s equations to make something glow. Chris is a big proponent of the top-down model of learning, and his Belgrade talk is all about the virtues of not knowing everything.