Gadget Master

You've heard of works of art that seem to track your eyes around the room, well take at look at this very eye-catching project!

A San Jose artist, Chris Eckert, has been working up a prototype for a dynamic, pan-handling sculpture dubbed "Gimme". It's an Arduino-based system that uses sensors to track a person's movement, and once they are located the sculpture is intended to solicit money!

It amounts to an eyeball and a rattling tin. But the eyeball will track your movements. (Kind of reminds me of the Steam Punk eyePod.)

Thanks to Arduino Playground for highlighting this:

The sculpture is controlled by an Arduino Pro Mini. Stepper motors are driven by two Pololu A4983 Stepper Motor Driver Carriers. The microcontroller, stepper drivers, and sensors are all mounted on a custom circuit board made with Eagle CAD.

The key element that interests us is his use of sensors. Chris writes on his blog:

I want rudimentary motion tracking over 180 degrees so my first setup was a static array of five sensors. My idea was that, as an object moves past these five sensors, one or more would register a distance. Interpreting this information with an Arduino micro-controller, I could roughly point toward the object.

Simple idea but it got a little more complicated. The difficult thing about the sensors I'm using it that their output falls off exponentially with distance; objects farther away produce a MUCH smaller sensor change than objects close up. To get an approximately accurate distance from these sensors, I had to linearize the sensor outputs - lots of math. Took a while but I finally got it working well.

Having found "holes" in his sensor pattern - places where he could stand and none of the sensors could see him - he decided to try a different approach, rather than just increase the number of sensors to process.

Rather than having static sensors, I thought I'd sweep the sensors. I attached three sensors to a servo and slowly swept them back-and-forth. If any of the sensors detect an object, they move the three sensor array so that the centre sensor has the smallest distance. Voilà - motion tracking.

Read more details on the project, and see some more images from his gallery (click on the slides to enlarge the image).