Not too long ago I wrote my first Instructable, on how to disassemble a Samsung slider cell phone. So now I’m an Instructables user, and I get emails from them periodically listing the latest and greatest instructable projects. The last one had two that looked interesting, a remote control lawnmower (the subject of another column), and something called “The eyewriter“. From the description it seemed to involved an IR camera focused on the eye and software to track it. Canon had a similar system on their 35mm film SLR cameras, and I think it’s making a comeback on their high end digital SLRs as well. It sounds pretty neat, but what I found was a whole lot more, another example that the internet can enable truly profound collaboration to improve the human condition, and I’m not just talking about the singing fish again.
The eyewriter project was begun to allow people with Amyotrophic lateral sclerosis, more commonly known in the US as Lou Gehrig’s disease, to draw and communicate. People with ALS are often completely paralyzed with the exception of being able to move their eyes. From the originators of the eyewriter project:
The EyeWriter project is an ongoing collaborative research effort to empower people who are suffering from ALS with creative technologies. It is a low-cost eye-tracking apparatus & custom software that allows graffiti writers and artists with paralysis resulting from Amyotrophic lateral sclerosis to draw using only their eyes. This project is an attempt to address a gap in the development of low-end eyetracking systems, ie to make a super-cheap, eye-tracker that could be made by almost anyone, almost anywhere.
So how about that?
The hardware for this project is simple and straightforward. Sunglasses (aka “stunnas“), an IR sensitive digital camera without auto-iris, a new lens, lens mount, IR LEDs, and miscellaneous wires and other items. This Instructable used the Sony PS3 Eye camera. The camera is disassembled and the stock lens and mount are replaced with new ones that have a shorter focal length. IR LEDs are placed around the periphery of the camera to illuminate the pupil, and software interfaces with the camera to track the eye and determine where it is pointing. The IR illumination combined with a visible light filter result in a high contrast image of the eye that is easy for software to track. The IR LED circuit does not use a limiting resistor, which would be a useful addition to extend the life of the LEDs.
The software comes in two parts, one that interfaces with the camera to track the eye, and drawing software that is optimized for easy control with eye movements. From my reading it’s not clear if the tracking software can be installed on a computer as a mouse driver, giving control over the entire computer to the user, or whether it’s only used by the drawing software. If it’s not, then enabling it to serve as a mouse seems like a very useful improvement.
The drawing software allows drawing lines, optionally snapped to a grid, plus the usual scaling, filling, and other graphical operations.
All of the software is open source.
I’d rate this gadget as medium difficulty. There is some simple fabrication, hotrodding of a webcam, some simple electronics (no soldering needed, although it would make the project more reliable). The software is available in executable form so no need to compile. It seems like a great base for experimentation to me.