We’re considering using the glint from an IR light on the pupil to stabilize the calibration. One problem we have right now is that shadows cast from top eyelashes creates a shadow that can blend with the pupil. Zach asked Lee and me to work on a dimming IR LED that could be mounted on the glasses (or the future camera mount) to remove this shadow.

Lee and I consulted our physical computing teacher about using a 555 timer to set up a dimming LED. Here’s the schematic for the 555 timer and a potentiometer (acts as a variable resistor) to dim an LED with 5V power.

Mark time = 0.7 (R1 x R2) x C1
Space time = 0.7 x R2 x C1

R1_A is potentiometer (variable resistor). In our case = from 0 – 50K
R1_B is another resistor. In this scenario we want it to be about half of R1_A where the LED dims partway (and not all the way down). So here = 22K (closest standard resistor value)

R1 = R1_A + R1_B

In this scenario:
R1_min = 0 + 22K = 22K
R1_max = 50 + 22K = 72K

C2 = .01 uF

C1 = ?
R2 = ?

We test multiple values for C1 and R2 based on what was available to us.
C1 = .047 uF and R2 = 470K ohm worked best.

To build this circuit, you also need to understand what each pin is on the 555 timer (see following diagram). Also here’s a single LED (can replace with IR LED) built on a 555 timer:

Here is a quick demo of the click functionality being developed for eyewriter.

Here is a video of the eyewriter controling and the HUD in action. There is a slight lag between the video of myself and the screen.

HUD DEMO from Luke BrownGold on Vimeo.

Here is a little hack I managed to pull off in order to improve the IR LED illumination. I took two IR LED’s from an old-school trackball mouse. These LED’s have a small magnifier on the casing to increase range and spread. I placed them at the top and bottom of the mounted lens in order to eliminate shadows.

Here are some details about possible sources of power on the PS3 Eye:

2.13v microphone

3.25v (unknown points, refer to image)

2.53v led (blue)

This class we were quite lucky to have a visitor who is an expert in assistive tech, Mark Surabian. He gave a great lecture / demo, which started with the willowbrook scandal and gave a general overview of the assistive tech landscape. He said something I personally found very touching, that the key to assistive tech is “empathy not sympathy”

In addition, he gave a good overview of the eyegaze system, and eye tracking generally.  He also demoed some interesting eye tracking interfaces (for typing and computer control).

an incomplete but almost a full shot of the eyewriter collab rocking their glasses: