PhotoTransistor Based Eye-Tracking


The applications of eye-tracking devices are endless, which is why we always get excited to see new techniques in measuring the absolute position of the human eye. Cornell students [Michael and John] took on an interesting approach for their final project and designed a phototransistor based eye-tracking system.

We can definitely see the potential of this project, but for their first prototype, the system relies on both eye-tracking and head movement to fully control a mouse pointer. An end-product design was in mind, so the system consists of both a pair of custom 3D printed glasses and a wireless receiver; thus avoiding the need to be tethered to the computer under control . The horizontal position of the mouse pointer is controlled via the infrared eye tracking mechanism, consisting of an Infrared LED positioned above the eye and two phototransistors located on each side of the eye. The measured analog data from the phototransistors determine the eye’s horizontal position. The vertical movement of the mouse pointer is controlled with the help of a 3-axis gyroscope mounted to the glasses. The effectiveness of a simple infrared LED/phototransistor to detect eye movement is impressive, because similar projects we’ve seen have been camera based. We understand how final project deadlines can be, so we hope [Michael and John] continue past the deadline with this one. It would be great to see if the absolute position (horizontal and vertical) of the eye can be tracked entirely with the phototransistor technique.

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How to use the Kenetis KL25Z Freedom board as an HID mouse

hid-usb-mouse-from-Freescale-dev-board[Eric] is interested in turning this Freedom development board into an air mouse by using the onboard accelerometer. But he had to work through the particulars of the USB HID mouse class before he could get that done.

This Freescale FRDM-KL25Z is one of the awesome ARM boards we looked at a year ago. Can you believe you can get this thing for like thirteen bucks? We suppose the gotcha is that the CodeWarrior IDE meant for use with them is not entirely free. But there is a free trial, and [Eric] shows how much easier it is to tailor the USB stack for your needs with it.

Don’t worry though. If you’re like us and use Open Source For The Win he’s got you covered as well. When you’re done reading his HID mouse writeup head on over to his six-part tutorial for building a free toolchain for the Kenetis boards.

Fun with LED matrix and mouse


[Brad] just acquired a 32×32 RGB LED matrix and he jumped right into the deep end with his first project. To try out his skills on the device he used an Arduino to drive a slew of pixels with bouncing-ball physics.

The demo starts off with a hail storm of multi-colored falling pixels. In the center of the storm is the cursor, which he controls with a PS2 mouse. That happens to be a ball mouse which makes sense as we don’t remember having seen any optical mice as of late that weren’t USB. The PS2 protocol is easy to read using a microcontroller; more about that in [Brad’s] project write up.

By holding down the left mouse button he can draw persistent pixels on the screen. The falling balls then interact by bouncing off of the obstacles. The image above shows a frame on three sides of the screen which has trapped the pixels near the bottom. He can also erase pixels, which has the effect of draining the trapped balls like a hole in a bucket of water. Neat!

Bouncing ball physics are fun to experiment with. Here’s one being driven by an analog computer.

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Hackaday Links: Sunday, May 26th, 2013


The warmer months cometh and it’s time to think of this year’s Burning Man. [Matt’s] already set himself up with a sound-reactive LED project he calls the Seed of Life.

Older readers, and those who really know their hobby electronic history, will know the name Heathkit. Many readers tipped us off about their triumphant return. We’re not sure what form this reincarnation will take, but you can help shape it by participating in the survey.

Dust off that MSP430 launchpad and turn it into a composite video Pong console.

Here’s a way to use your Android phone as a computer mouse.

We’re not quite sure what this is, but turn your volume down before watching the video about a modular sythesizer hack.

[Arkadiusz Spiewak] wrote in to share some of the printing success (translated) he’s had recently with the H-bot style printer we saw a while back.

Strap an Arduino and an Electric Imp to your arm (and everyone else’s) and it’ll remember everyone you meet. You know, kind of like Google Glass but with geeky arm-wear instead of geeky headgear?

And finally, [Nerick] has just finished a thermometer project using Nixie tubes (translated).

GUI window manager on an AVR chip


This project is reminiscent of the old days when window managers were an amazing new idea. The difference is that this window-based GUI is running on an ATmega1284 microcontroller. But the behavior and speed of the interface is pretty much exactly what you’d expect if working on an early 90’s home computer. It even uses a mouse as input.

So how is this even possible? The key to the project is a serial to VGA module which handles the heavy lifting involved with generating a VGA signal. We featured one of [Andrew’s] past projects which used an AVR chip to generate the VGA signal. But that doesn’t leave nearly enough cycles to implement something like a window manager, not to mention the fact that it got nowhere near the resolution shown here.

He uses a serial mouse with an RS-232 converter chip to interact with the windows. This is best shown in his video after the break. He’s able to generate and interact with new windows. He even implemented a set of rudimentary controls which allow him to adjust the theme of the windows and drive the audio playback feature included on that VGA controller he’s using.

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Wall wart computer mouse


This rather bulky looking wall wart is actually a computer mouse. Sure, it may cause your hand to cramp horribly if used for any length of time. But some would say it’s worth that for the hipster value of the thing.

The rather odd shape is somewhat explained by the fact that this was sourced from Ikea. After gutting the transformer found inside the plastic case he had plenty of room to work with. He drilled a hole so that the sensor from a Logitech USB optical mouse can pick up the movement of the mouse. He also got pretty creative when it came to the buttons. The two prongs of the wall plug pivot horizontally to affect the momentary press switches inside.

After the break you can see a quick demo of the project. [Alec] doesn’t consider it to be complete. He wants to make a couple of improvements which include adding weight to make it feel more like the original wall wart, and finding a way to hide the hole he drilled for the sensor.

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Robotic rat torments and depresses real rats


Animal testing has always been a subject of much debate. On one hand, it allows us to determine if something is probably safe for humans. On the other hand, it’s injuring and killing the very animals that help us escape that same fate. Any way you look at it, be thankful you’re not a lab rat. Being a mammal, they share a similar physiology with us. They are also easy to breed and easy to dispose of. These characteristics make them the prime subject for testing the safety of drugs and treatments that might one day be used on humans. Scientists at Waseda University in Tokyo, Japan, have created a new rat nemesis – the WR-3, a robot designed specifically to stress and depress lab animals in the name of science.

Depression isn’t normally something rats have to worry about in the wild. So, the WR-3 tries to instill it upon them. The robot has three functions: attacking continuously (relentlessly rams the victim), attacking interactively (attacks for 5 seconds whenever the victim moves, then stops), and chasing (stays right next to the victim but never attacks). The scientists found that the best way to make the rats depressed was to attack them continuously in their youth, then attack interactively as they get older.

With the data the scientists gain from these new experiments, they hope to learn more about human depression and hopefully come up with more successful treatments. There isn’t a lot of specific information we could find about the WR-3, but we’ll keep you posted.

[via Gizmodo]