How To Build Your Own Cat Door

October 2, 2011 by Mike Szczys 29 Comments

[Dino] continues his to satisfy his weekly hacking goal by building a cat door for his pets. He has a Habitat For Humanity resale store nearby that was doing a 50% off sale on doors. So he picked up a six-panel door and set to work.

The first step is drawing out the opening and cutting it with a jigsaw. Once he was done, there’s some reinforcement work to be done because this is a hollow-core door. Since he had already cut a bit of the bottom off of the door to fit his jamb opening, he had some wood stock that was already the right thickness. That bit was secured to the top and bottom of the opening with glue and some brads. The same was done on the sides with a different piece of scrap, then the door was hung in the opening to reach the point in the project seen above.

Here [Dino] prepares to add a flap to cover the opening. He used acrylic for the flap because it’s light-weight and clear. A piece of piano hinge makes it easy to swing in both directions. The final touch is a magnet which keeps the flap from swinging in the breeze using parts from a magnetic cabinet latch. No sooner does he have the flap in place than a brave kitty gives it a test run.

Hopefully he doesn’t have the kind of pests that caused other hackers to build facial recognition cat door locks.

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Robotic Arm Follows The Movements Of Your Own Limbs

October 2, 2011 by Mike Szczys 3 Comments

[Alejandro] and his friends recently finished a first prototype of scratch-built robotic arm. They’ve got some nice electronics bench equipment for use with a project like this, but for the actual fabrication work it’s off to the kitchen.

As you can see in the video after the break, they’re using PVC as the stock material in this build. Flat sheets are produced by slitting a PVC pipe down the middle, warming it in oven until soft, then compressing it between two floor tiles with a big jug of water used as a weight for the makeshift press. Mounting holes for the servo motors that make up the joints are drilled with a hand drill, and the assembly was affixed to an old CD as a base.

Once assembled they wired it to the control circuitry and build a set of sensors that you wear on your arm. Now your elbow, wrist, and pointer finger are in control of the servos. A demonstration of this functionality starts around two minutes into the video.

We’ve seen other examples of robot arms built without the use of machine tools. This arm made out of ShapeLock plastic is one of the most interesting examples.

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[Clement] Sees The Cargo Bike And Raises A Bicycle Cargo Trailer

October 2, 2011 by Mike Szczys 16 Comments

[Clement] and his friends were going on a long bike tour and needed a way to carry their gear along with them. They set to work and managed to build this cargo trailer from mostly reused materials.

The only part of this trailer that is reused junk is the connection mechanism that lets you attach it to just about any bike. That was made (presumably in a machine shop) to act as a removable pipe clamp, making it pretty quick to swap between different bikes. It has a universal joint welded to it so that the angle of the seat post won’t affect how the trailer rides.

A goose neck keeps the trailer far enough back to avoid getting in the way of the rear wheel. The mesh basket was made from parts of an old industrial machine. The rear wheel is attached with a swing-arm that has what looks like a rubber bumper to act as a shock absorber. But if you want to make sure a big bump doesn’t send your luggage flying, [Clement] included a picture at the bottom of his post showing a much nicer spring shock on a different bike trailer.

If you’re confused by the title of this post you must have missed the cargo bike that was recently featured.

Hacking SPOT Personal Satellite Tracker To Pass More Information

October 1, 2011 by Mike Szczys 38 Comments

For less than $100 you can buy a little tracking module that will upload your location to a satellite. But you’ll only get latitude and longitude information. [Natrium42] spent some time reverse engineering the hardware, and the communications protocol, to allow custom data to be transferred using a SPOT module.

The flat fee for the hardware includes a one-year service plan allowing you to tack your device on the SPOT website. [Natrium42] started poking around in the transmitted data packages, and figured he could push custom messages like altitude data if he had some way to encode it as a valid latitude/longitude package. He found that location data is transmitted as two sets of three bytes each. The four least significant bits of each set get rounded by the server, leaving a total of 40 usable bits between the two data sets. He wrote encoding and decoding functions that will allow you to transfer whatever information you want.

So what is this good for? To get the process working he removed the MSP430 microcontroller from the board and is using his own replacement. So you can transmit GPS data from the onboard module, your own module, or sensor data for anything you’re able to hook up the to the replacement uC.

Passive RFID Tag Cloning

September 30, 2011 by Mike Szczys 34 Comments

Here’s an open source RFID cloner design that is about the same size as a standard RFID key card. It doesn’t need a battery to capture key codes, just the magnetic field generated by an RFID reader. You can see the functionality demonstrated in the video after the break. By holding the bottom button as the cloner is moved in range of the RFID reader, the microcontroller goes into learning mode. Now just hold up the card you wish to clone and the LED just above the buttons will light up when it has captured the code. Now the device will act just as the original RFID tag did.

This was developed by [Ramiro], the same person who built the barebones RFID emulator we saw a few days ago. When researching that story we complete skipped over this gem. He’s posted a ton of information on the tag itself. It doesn’t look like he has any PCBs or kits left, but the schematic and code are available for download. You should check in on the design considerations section because it discusses the read/write function that isn’t built into the current version. That’s why you see some add-on components on the hardware used in the demo video.

It seems like this is a lot more user-friendly than the last RFID spoofer we looked at.

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New BigDog Video Doesn’t Fail To Impress

September 30, 2011 by Mike Szczys 40 Comments

Those following the evolution of quadrupedal assist robots will recognize the specimen seen above as a relative of BigDog. This is AlphaDog, one of the latest prototypes in Boston Dynamics’ Legged Squadron Support Systems program. It’s designed to carry 400 pounds of payload, which explains the disc weights seen on either side of the torso. Like its diminutive sibling, LittleDog, it’s able to take on all kinds of terrain. Here it’s being tested with boxes full of rocks.

The robot is capable of picking itself up and getting under way again without intervention. The first video after the break shows test footage where the robot starts nearly upside-down and has no trouble righting itself again. When we looked in on a biped version back in 2009 we also linked to the BigDog prototype which showed developers trying to tip it over mid stride. This version has the same balance resiliency.

Also embedded after the break is a video showing the evolution of the design over about seven years of development.

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Get Digital Plastic Surgery Thanks To OpenFrameworks And Some Addons

September 30, 2011 by Mike Szczys 27 Comments

[Kyle McDonald] is trying out a new look, at least in the digital world, with the help of some openFrameworks video plugins. He’s working with [Arturo Castro] to make real-time facial substitution as realistic as possible. You can see that [Arturo’s] own video has a different take on shading and color of the facial alterations that makes them a bit less realistic than what [Kyle] was able to accomplish (see that clip after the break).

The setup depends on some facial tracking software developed by [Jason Saragih]. That package is wrapped in ofxFaceTracker (already linked at the top of this article) which makes it play nicely with openFrameworks. From there, it’s just a matter of image processing. If you think you’re up to the challenge, grab your own copies of the source code and get to work. We’re shocked by how real this looks, even when [Kyle] grabs his cheeks and stretches them out. If someone can fix some of the artifacts around the edges of the sampled faces this would be ready to use when video-conferencing.

It kind of makes us think of technology seen in The Running Man.

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