A Webcam Based Posture Sensor

Webcam based posture sensor

Even for hobby projects, iteration is very important. It allows us to improve upon and fine-tune our existing designs making them even better. [Max] wrote in to tell us about his latest posture sensor, this time, built around a webcam.

We covered [Max's] first posture sensor back in February, which utilized an ultrasonic distance sensor to determine if you had correct posture (or not). Having spent time with this sensor and having received lots of feedback, he decided to scrap the idea of using an ultrasonic distance sensor altogether. It simply had too many issues: issues with mounting the sensor on different chairs, constantly hearing the clicking of the sensor, and more.  After being inspired by a very similar blog post to his original that mounted the sensor on a computer monitor, [Max] was back to work. This time, rather than using an ultrasonic distance sensor, he decided to use a webcam. Armed with Processing and OpenCV, he greatly improved upon the first version of his posture sensor. All of his code is provided on his website, be sure to check it out and give it a whirl!

Iteration leads to many improvements and it is an integral part of both hacking and engineering. What projects have you redesigned or rebuild? Let us know!

Interactive 3D Projection is Foggy At Best

fog proj

Have a projector and a smoke machine handy? You might want to give this fog projection thing a shot! It’s called the MisTable and it’s a three-dimensional playground for interactive manipulation of images.

It’s a project by Bristol Interaction and Graphics group of the University of Bristol, and it’s an interesting twist on 3D projection. They’ve created what they call the MisTable which features a smoke machine, “smoke screens”, and three projectors. What it results in is an interactive table for two people. The tabletop surface is a display, as is the see through fog in front of each person (the “fog screens”).

While it is fairly easy to understand and explain, there’s a handy diagram after the following break showing how the system works. Our question is, when are one of you guys or gals going to try making one?

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Neo Geo Arcade Gets Second Life with a Raspberry Pi

neo-picade

An old Neo Geo Arcade, a Raspberry Pi, and some time were all [Matthew] needed to build this Pi Powered Arcade Emulator Cabinet.

Neo Geo was originally marketed by SNK as a very expensive home video console system. Much like the Nintendo Play Choice 10, SNK also marketed an arcade system, the MVS. The Neo Geo MVS allowed arcade operators to run up to six titles in a single cabinet. The MVS also allowed players to save games on memory cards.

[Matthew's] cabinet had seen better days. Most of the electronics were gone, the CRT monitor was dead, and the power supply was blown. Aside from a bit of wear, the cabinet frame was solid and the controls were in good shape. He decided it would be a good candidate for an emulator conversion.

We’ve seen some pretty awesome arcade conversions in the past, such as this Halloween rendition of Splatterhouse. For his conversion, [Matthew] stuck to the electronics, leaving most of the old arcade patina intact. The CRT did fire up after some components were replaced. [Matthew] ran into some refresh rate issues with the Raspberry Pi, so he opted to swap it out with a modern LCD monitor. Controls were wired up with the help of an I-PAC board.

[Matthew] had to write a driver to handle the I-PAC, but he says it was a good learning experience. Aside from the LCD screen, the result looks like it could be found in the back of an old bowling alley, or a smokey bar next to Golden Tee. Nice work, [Matthew]!

Magic Screwdriver Decides If You Watch TV Or Not

OLYMPUS DIGITAL CAMERA

Video projectors are great. They can easily produce a very large image to watch. With that large image comes a large screen, and who wants to look at a large screen when not watching TV? Well, [Steve] didn’t either so he set out to make a powered retractable screen for his projector. The best part about this one is that it is done in true DIY/hacker fashion. The parts used are definitely not intended to be used as anything close to a projector screen and the overall cost is kept to an absolute minimum.

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Bookworm Playing Bot Tests Programmer’s OCR Skills

bookworm-bot

Check out this brainy bot with [Jari] whipped up to dominate the Bookworm Deluxe scoreboard. The bot runs on top of a win32 machine, pulling screenshots to see the game board and simulating mouse clicks to play. The video after the jump shows that it plays like a champ, but it took some doing to get this far and [Jari] took the time to share all of the development details.

The hardest part of writing these types of bots is recognizing the game pieces. Check out all of the animation that’s going on in the still shot above… a lot of the tiles are obscured, there are different colors, and the tiles themselves shift as the bot spells and submits each word.

After some trial and error [Jari] settled on an image pre-processor which multiplies pixel values by themselves four times, then looks at each pixel with a 1/6 threshold to produce a black and white face for each tile. From there a bit of Optical Character Recognition compares each tile to a set of known examples. This works remarkably well, leading into the logic and dictionary part of the programming challenge.

Do you think this was easier or harder than the Bejeweled Blitz bot. That one was looking for specific pixel regions, this one is basically a focused roll-your-own OCR script.

 

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Panning GoPro Mount Catches Bad Drivers On Video

gopro-mount

[Chris] must live in a neighborhood with a lot of bad drivers. He built this motorized panning GoPro mount so he can record and share his neighbors’ mobile misadventures with the world. He started with a custom machined aluminum frame. The frame clips onto a suction cup mount grab bar. The stock GoPro mount sits on a machined HDPE puck, which is rotated by a NEMA 11 stepper motor. [Chris] used a Pololu A4988 stepper motor driver to handle the coils. Initially he used an Arduino to generate pulses for the stepper driver. A true Hackaday fan though, he decided that an Arduino was overkill, and broke out a 555 timer. A DPDT switch powers up the 555 and controls the stepper driver’s direction input. The electronics all fit neatly in a small project box which doubles as a hand controller.

While setting up for a test drive [Chris] found that he could only lock down one suction cup on his car’s curved sunroof. Considering the light weight of the GoPro, one suction cup is probably enough. Just to be safe, [Chris] added a rope leash down through the sunroof.

We think the stepper motor was a good choice for this project. Since the motor is direct drive, there are no gears to strip. The stepper’s holding torque also keeps the camera pointed in the right direction at highway speeds. With no wires directly connecting the GoPro to the car, [Chris] can spin the camera 360 degrees without worrying about tangles. Verifying the camera’s direction is just a matter of looking up through the car’s sunroof. Click past the break to see [Chris's] camera mount in action. 

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An Open Source iPad Display Adapter

OSCAR

Those fancy 2048×1536 pixel resolution displays found in the iPad 3 and 4 can be used for much more than high def Candy Crush and Netflix viewing. [Freddie] over in Southampton, UK built his own adapter to connect these high-resolution LCD panels to anything with a DisplayPort connection. It’s called OSCAR, and it’s the open source way to add a whole lot of pixels in a second (or third, or fourth….) monitor.

The LCD panels found in the iPad 3 and 4 don’t use the usual LVDS connection found in just about every other LCD panel ever made. It uses an extension of the DisplayPort protocol, meaning any graphics card with one of these ports already does the heavy lifting for this panel. The only other thing that’s needed is an adapter to control the power and backlight, which is easily handled by an ATMega32U4. This makes OSCAR Arduino compatible, making it easy to add sensors and USB playthings.

OSCAR is available on Kickstarter for £65 (~$100 USD) for the board itself. Adding to that, you’ll need to grab an iPad retina display through the usual channels for about $65. Not exactly cheap, but try finding another better-than-1080p display for that price.